Name
ngx_lua - Embed the power of Lua into Nginx
*This module is not distributed with the Nginx source.* See the
installation instructions.
Status
This module is under active development and is already production ready.
Version
This document describes ngx_lua v0.3.1rc21
(<https://github.com/chaoslawful/lua-nginx-module/tags>) released on 26
October 2011.
Synopsis
# set search paths for pure Lua external libraries (';;' is the default path):
lua_package_path '/foo/bar/?.lua;/blah/?.lua;;';
# set search paths for Lua external libraries written in C (can also use ';;'):
lua_package_cpath '/bar/baz/?.so;/blah/blah/?.so;;';
server {
location /inline_concat {
# MIME type determined by default_type:
default_type 'text/plain';
set $a "hello";
set $b "world";
# inline lua script
set_by_lua $res "return ngx.arg[1]..ngx.arg[2]" $a $b;
echo $res;
}
location /rel_file_concat {
set $a "foo";
set $b "bar";
# script path relative to nginx prefix
# $ngx_prefix/conf/concat.lua contents:
#
# return ngx.arg[1]..ngx.arg[2]
#
set_by_lua_file $res conf/concat.lua $a $b;
echo $res;
}
location /abs_file_concat {
set $a "fee";
set $b "baz";
# absolute script path not modified
set_by_lua_file $res /usr/nginx/conf/concat.lua $a $b;
echo $res;
}
location /lua_content {
# MIME type determined by default_type:
default_type 'text/plain';
content_by_lua "ngx.say('Hello,world!')"
}
location /nginx_var {
# MIME type determined by default_type:
default_type 'text/plain';
# try access /nginx_var?a=hello,world
content_by_lua "ngx.print(ngx.var['arg_a'], '\\n')";
}
location /request_body {
# force reading request body (default off)
lua_need_request_body on;
client_max_body_size 50k;
client_body_buffer_size 50k;
content_by_lua 'ngx.print(ngx.var.request_body)';
}
# transparent non-blocking I/O in Lua via subrequests
location /lua {
# MIME type determined by default_type:
default_type 'text/plain';
content_by_lua '
local res = ngx.location.capture("/some_other_location")
if res.status == 200 then
ngx.print(res.body)
end';
}
# GET /recur?num=5
location /recur {
# MIME type determined by default_type:
default_type 'text/plain';
content_by_lua '
local num = tonumber(ngx.var.arg_num) or 0
ngx.say("num is: ", num)
if num > 0 then
res = ngx.location.capture("/recur?num=" .. tostring(num - 1))
ngx.print("status=", res.status, " ")
ngx.print("body=", res.body)
else
ngx.say("end")
end
';
}
location /foo {
rewrite_by_lua '
res = ngx.location.capture("/memc",
{ args = { cmd = 'incr', key = ngx.var.uri } }
)
';
proxy_pass http://blah.blah.com;
}
location /blah {
access_by_lua '
local res = ngx.location.capture("/auth")
if res.status == ngx.HTTP_OK then
return
end
if res.status == ngx.HTTP_FORBIDDEN then
ngx.exit(res.status)
end
ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR)
';
# proxy_pass/fastcgi_pass/postgres_pass/...
}
location /mixed {
rewrite_by_lua_file /path/to/rewrite.lua;
access_by_lua_file /path/to/access.lua;
content_by_lua_file /path/to/content.lua;
}
# use nginx var in code path
# WARN: contents in nginx var must be carefully filtered,
# otherwise there'll be great security risk!
location ~ ^/app/(.+) {
content_by_lua_file /path/to/lua/app/root/$1.lua;
}
location / {
lua_need_request_body on;
client_max_body_size 100k;
client_body_buffer_size 100k;
access_by_lua '
-- check the client IP addr is in our black list
if ngx.var.remote_addr == "132.5.72.3" then
ngx.exit(ngx.HTTP_FORBIDDEN)
end
-- check if the request body contains bad words
if ngx.var.request_body and
string.match(ngx.var.request_body, "fsck")
then
return ngx.redirect("/terms_of_use.html")
end
-- tests passed
';
# proxy_pass/fastcgi_pass/etc settings
}
}
Description
This module embeds the Lua interpreter or LuaJIT into the nginx core and
integrates the powerful Lua threads (aka Lua coroutines) into the nginx
event model by means of nginx subrequests.
Unlike Apache's mod_lua
(<http://httpd.apache.org/docs/2.3/mod/mod_lua.html>) and Lighttpd's
mod_magnet (<http://redmine.lighttpd.net/wiki/1/Docs:ModMagnet>), Lua
code written atop this module can be *100% non-blocking* on network
traffic as long as you use the ngx.location.capture or
ngx.location.capture_multi interfaces to let the nginx core do all your
requests to mysql, postgresql, memcached, redis, upstream http web
services, and etc etc etc (see [[HttpDrizzleModule]], ngx_postgres
(<http://github.com/FRiCKLE/ngx_postgres/>), [[HttpMemcModule]],
[[HttpRedis2Module]] and [[HttpProxyModule]] modules for details).
The Lua interpreter instance is shared across all the requests in a
single nginx worker process.
Request contexts are isolated from each other by means of Lua
(lightweight) threads (aka Lua coroutines). And Lua modules loaded are
persistent on the nginx worker process level. So the memory footprint is
quite small even when your nginx worker process is handling 10K requests
at the same time.
Directives
lua_code_cache
syntax: *lua_code_cache on | off*
default: *lua_code_cache on*
context: *main, server, location, location if*
Enable or disable the Lua code cache for set_by_lua_file,
content_by_lua_file, rewrite_by_lua_file, and access_by_lua_file, and
also force Lua module reloading on a per-request basis.
The Lua files referenced in set_by_lua_file, content_by_lua_file,
access_by_lua_file, and rewrite_by_lua_file won't be cached at all, and
Lua's "package.loaded" table will be cleared at every request's entry
point (such that Lua modules won't be cached either). So developers and
enjoy the PHP-way, i.e., edit-and-refresh.
But please note that Lua code inlined into nginx.conf like those
specified by set_by_lua, content_by_lua, access_by_lua, and
rewrite_by_lua will *always* be cached because only nginx knows how to
parse "nginx.conf" and the only way to tell it to re-load the config
file is to send a "HUP" signal to it or just to restart it from scratch.
For now, ngx_lua does not support the "stat" mode like Apache's
"mod_lua", but we will work on it in the future.
Disabling the Lua code cache is mainly used for Lua development only
because it has great impact on the over-all performance and is strongly
discouraged for production uses. Also, race conditions when reloading
Lua modules are common for concurrent requests when the code cache is
off.
lua_regex_cache_max_entries
syntax: *lua_regex_cache_max_entries <num>*
default: *lua_regex_cache_max_entries 1024*
context: *http*
Specifies the maximal entries allowed in the worker-process-level
compiled-regex cache.
The regular expressions used in ngx.re.match, ngx.re.gmatch, ngx.re.sub,
and ngx.re.gsub will be cached in this cache if the regex option "o"
(i.e., compile-once flag) is specified.
The default entries allowed is 1024.
When the user Lua programs are exceeding this limit, those new regexes
will not be cached at all (as if no "o" option is ever specified), and
there will be one (and only one) warning in nginx's "error.log" file,
like this 2011/08/27 23:18:26 [warn] 31997#0: *1 lua exceeding regex
cache max entries (1024), ...
You shouldn't specify the "o" regex option for regexes (and/or "replace"
string arguments for ngx.re.sub and ngx.re.gsub) that are generated *on
the fly* and give rise to infinite variations, or you'll quickly reach
the limit specified here.
lua_package_path
syntax: *lua_package_path <lua-style-path-str>*
default: *The content of LUA_PATH environ variable or Lua's compiled-in
defaults.*
context: *main*
Set the Lua module searching path used by scripts specified by
set_by_lua, content_by_lua and others. The path string is in standard
Lua path form, and ";;" can be used to stand for the original path.
lua_package_cpath
syntax: *lua_package_cpath <lua-style-cpath-str>*
default: *The content of LUA_CPATH environ variable or Lua's compiled-in
defaults.*
context: *main*
Set the Lua C-module searching path used by scripts specified by
set_by_lua, content_by_lua and others. The cpath string is in standard
Lua cpath form, and ";;" can be used to stand for the original cpath.
set_by_lua
syntax: *set_by_lua $res <lua-script-str> [$arg1 $arg2 ...]*
context: *main, server, location, server if, location if*
phase: *rewrite*
Execute user code specified by "<lua-script-str>" with input arguments
"$arg1 $arg2 ...", and set the script's return value to $res in string
form. In "<lua-script-str>" code the input arguments can be retrieved
from "ngx.arg" table (index starts from 1 and increased sequentially).
set_by_lua directives are designed to execute small and quick codes.
Nginx event loop is blocked during the code execution, so you'd better
not call anything that may be blocked or time-consuming.
Note that set_by_lua can only output a value to a single Nginx variable
at a time. But a work-around is also available by means of the
ngx.var.VARIABLE interface, for example,
location /foo {
set $diff ''; # we have to predefine the $diff variable here
set_by_lua $sum '
local a = 32
local b = 56
ngx.var.diff = a - b; -- write to $diff directly
return a + b; -- return the $sum value normally
';
echo "sum = $sum, diff = $diff";
}
This directive can be freely mixed with all the directives of
[[HttpRewriteModule]], [[HttpSetMiscModule]], and
[[HttpArrayVarModule]]. All of these directives will run in exactly the
same order that they are written in the config file. For example,
set $foo 32;
set_by_lua $bar 'tonumber(ngx.var.foo) + 1';
set $baz "bar: $bar"; # $baz == "bar: 33"
This directive requires the ngx_devel_kit
(<https://github.com/simpl/ngx_devel_kit>) module.
set_by_lua_file
syntax: *set_by_lua_file $res <path-to-lua-script> [$arg1 $arg2 ...]*
context: *main, server, location, server if, location if*
phase: *rewrite*
Basically the same as set_by_lua, except the code to be executed is in
the file specified by "<path-lua-script>".
When the Lua code cache is on (this is the default), the user code is
loaded once at the first request and cached. Nginx config must be
reloaded if you modified the file and expected to see updated behavior.
You can disable the Lua code cache by setting "lua_code_cache off;" in
your nginx.conf.
This directive requires the ngx_devel_kit
(<https://github.com/simpl/ngx_devel_kit>) module.
content_by_lua
syntax: *content_by_lua <lua-script-str>*
context: *location, location if*
phase: *content*
Act as a content handler and execute user code specified by
"<lua-script-str>" for every request. The user code may call predefined
APIs to generate response content.
The use code is executed in a new spawned coroutine with independent
global environment (i.e. a sandbox).
Do not use this directive and other content handler directives in a same
location. For example, it's bad to use this directive with a proxy_pass
directive in the same location.
content_by_lua_file
syntax: *content_by_lua_file <path-to-lua-script>*
context: *location, location if*
phase: *content*
Basically the same as content_by_lua, except the code to be executed is
in the file specified by "<path-lua-script>".
Nginx variables can be used in "<path-to-lua-script>" string, in order
to provide greater flexibility in practice. But this feature must be
used carefully, so is not recommend for beginners.
When the Lua code cache is on (this is the default), the user code is
loaded once at the first request and cached. Nginx config must be
reloaded if you modified the file and expected to see updated behavior.
You can disable the Lua code cache by setting lua_code_cache "off" in
your "nginx.conf" file.
rewrite_by_lua
syntax: *rewrite_by_lua <lua-script-str>*
context: *http, server, location, location if*
phase: *post-rewrite*
Act as a rewrite phase handler and execute user code specified by
"<lua-script-str>" for every request. The user code may call predefined
APIs to generate response content.
This hook uses exactly the same mechamism as content_by_lua so all the
nginx APIs defined there are also available here.
Note that this handler always runs *after* the standard
[[HttpRewriteModule]]. So the following will work as expected:
location /foo {
set $a 12; # create and initialize $a
set $b ""; # create and initialize $b
rewrite_by_lua 'ngx.var.b = tonumber(ngx.var.a) + 1';
echo "res = $b";
}
because "set $a 12" and "set $b """ run *before* rewrite_by_lua.
On the other hand, the following will not work as expected:
? location /foo {
? set $a 12; # create and initialize $a
? set $b ''; # create and initialize $b
? rewrite_by_lua 'ngx.var.b = tonumber(ngx.var.a) + 1';
? if ($b = '13') {
? rewrite ^ /bar redirect;
? break;
? }
?
? echo "res = $b";
? }
because "if" runs *before* rewrite_by_lua even if it's put after
rewrite_by_lua in the config.
The right way of doing this is as follows:
location /foo {
set $a 12; # create and initialize $a
set $b ''; # create and initialize $b
rewrite_by_lua '
ngx.var.b = tonumber(ngx.var.a) + 1
if ngx.var.b == 13 then
return ngx.redirect("/bar");
end
';
echo "res = $b";
}
It's worth mentioning that, the "ngx_eval" module can be approximately
implemented by rewrite_by_lua. For example,
location / {
eval $res {
proxy_pass http://foo.com/check-spam;
}
if ($res = 'spam') {
rewrite ^ /terms-of-use.html redirect;
}
fastcgi_pass ...;
}
can be implemented in terms of "ngx_lua" like this
location = /check-spam {
internal;
proxy_pass http://foo.com/check-spam;
}
location / {
rewrite_by_lua '
local res = ngx.location.capture("/check-spam")
if res.body == "spam" then
ngx.redirect("/terms-of-use.html")
end
';
fastcgi_pass ...;
}
Just as any other rewrite phase handlers, rewrite_by_lua also runs in
subrequests.
Note that calling "ngx.exit(ngx.OK)" just returning from the current
rewrite_by_lua handler, and the nginx request processing control flow
will still continue to the content handler. To terminate the current
request from within the current rewrite_by_lua handler, calling ngx.exit
with status >= 200 ("ngx.HTTP_OK") and status < 300
("ngx.HTTP_SPECIAL_RESPONSE") for successful quits and
"ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR)" (or its friends) for
failures.
If one uses [[HttpRewriteModule]]'s rewrite directive to change the URI
and initiate location re-lookups (kinda like internal redirections),
then rewrite_by_lua and rewrite_by_lua_file will be skipped altogether
in the current location. For example,
location /foo {
rewrite ^ /bar;
rewrite_by_lua 'ngx.exit(503)';
}
location /bar {
...
}
Here the Lua code "ngx.exit(503)" will never run while all the Lua code
(except access phase handlers) in the "/bar" location will not be
affected anyway. Similarly, "rewrite ^ /bar last" will also initiate a
location re-lookup. If you use the "break" modifier for the rewrite
directive, however, no location re-lookup will be triggered, and
therefore, the rewrite-phase Lua code will still be run as normal.
rewrite_by_lua_file
syntax: *rewrite_by_lua_file <path-to-lua-script>*
context: *http, server, location, location if*
phase: *post-rewrite*
Same as rewrite_by_lua, except the code to be executed is in the file
specified by "<path-lua-script>".
Nginx variables can be used in "<path-to-lua-script>" string, in order
to provide greater flexibility in practice. But this feature must be
used carefully, so is not recommend for beginners.
When the Lua code cache is on (this is the default), the user code is
loaded once at the first request and cached. Nginx config must be
reloaded if you modified the file and expected to see updated behavior.
You can disable the Lua code cache by setting lua_code_cache "off" in
your "nginx.conf" file.
access_by_lua
syntax: *access_by_lua <lua-script-str>*
context: *http, server, location, location if*
phase: *post-access*
Act as an access phase handler and execute user code specified by
"<lua-script-str>" for every request. The user code may call predefined
APIs to generate response content.
This hook uses exactly the same mechanism as content_by_lua so all the
nginx APIs defined there are also available here.
Note that this handler always runs *after* the standard
[[HttpAccessModule]]. So the following will work as expected:
location / {
deny 192.168.1.1;
allow 192.168.1.0/24;
allow 10.1.1.0/16;
deny all;
access_by_lua '
local res = ngx.location.capture("/mysql", { ... })
...
';
# proxy_pass/fastcgi_pass/...
}
That is, if a client address appears in the blacklist, then we don't
have to bother sending a MySQL query to do more advanced authentication
in access_by_lua.
It's worth mentioning that, the "ngx_auth_request" module can be
approximately implemented by access_by_lua. For example,
location / {
auth_request /auth;
# proxy_pass/fastcgi_pass/postgres_pass/...
}
can be implemented in terms of "ngx_lua" like this
location / {
access_by_lua '
local res = ngx.location.capture("/auth")
if res.status == ngx.HTTP_OK then
return
end
if res.status == ngx.HTTP_FORBIDDEN then
ngx.exit(res.status)
end
ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR)
';
# proxy_pass/fastcgi_pass/postgres_pass/...
}
Just as any other access phase handlers, access_by_lua will *not* run in
subrequests.
Note that calling "ngx.exit(ngx.OK)" just returning from the current
access_by_lua handler, and the nginx request processing control flow
will still continue to the content handler. To terminate the current
request from within the current access_by_lua handler, calling
"ngx.exit(status)" where status >= 200 ("ngx.HTTP_OK") and status < 300
("ngx.HTTP_SPECIAL_RESPONSE") for successful quits and
"ngx.exit(ngx.HTTP_INTERNAL_SERVER_ERROR)" or its friends for failures.
access_by_lua_file
syntax: *access_by_lua_file <path-to-lua-script>*
context: *http, server, location, location if*
phase: *post-access*
Same as access_by_lua, except the code to be executed is in the file
specified by "<path-lua-script>".
Nginx variables can be used in "<path-to-lua-script>" string, in order
to provide greater flexibility in practice. But this feature must be
used carefully, so is not recommend for beginners.
When the Lua code cache is on (this is the default), the user code is
loaded once at the first request and cached. Nginx config must be
reloaded if you modified the file and expected to see updated behavior.
You can disable the Lua code cache by setting lua_code_cache "off" in
your "nginx.conf" file.
header_filter_by_lua
syntax: *header_filter_by_lua <lua-script-str>*
context: *http, server, location, location if*
phase: *output-header-filter*
Use Lua defined in "<lua-script-str>" to define an output header filter.
For now, the following Nginx Lua APIs are disabled in this context:
* Output API (e.g., ngx.say and ngx.send_headers)
* Control APIs (e.g., ngx.exit)
* Subrequest APIs (e.g., ngx.location.capture and
ngx.location.capture_multi)
Here's a small example of overriding a response header (or adding if it
does not exist) in our Lua header filter:
location / {
proxy_pass http://mybackend;
header_filter_by_lua 'ngx.header.Foo = "blah"';
}
This directive was first introduced in the "v0.2.1rc20" release.
header_filter_by_lua_file
syntax: *header_filter_by_lua_file <path-to-lua-script-file>*
context: *http, server, location, location if*
phase: *output-header-filter*
Use Lua code defined in a separate file specified by
"<path-to-lua-script-file>" to define an output header filter.
This is very much like header_filter_by_lua except that it loads Lua
code from an external Lua source file.
This directive was first introduced in the "v0.2.1rc20" release.
lua_need_request_body
syntax: *lua_need_request_body <on | off>*
default: *off*
context: *main | server | location*
phase: *depends on usage*
Force reading request body data or not. The client request body won't be
read, so you have to explicitly force reading the body if you need its
content.
If you want to read the request body data from the $request_body
variable, make sure that your have configured client_body_buffer_size to
have exactly the same value as client_max_body_size.
If the current location defines rewrite_by_lua or rewrite_by_lua_file,
then the request body will be read just before the rewrite_by_lua or
rewrite_by_lua_file code is run (and also at the "rewrite" phase).
Similarly, if only content_by_lua is specified, the request body won't
be read until the content handler's Lua code is about to run (i.e., the
request body will be read at the content phase).
You're recommended to use the ngx.req.read_body function and
ngx.req.discard_body for finer control over the request body reading
process though.
The same applies to access_by_lua and access_by_lua_file.
lua_shared_dict
syntax: *lua_shared_dict <name> <size>*
default: *no*
context: *main*
phase: *depends on usage*
Declares a shared memory zone named "<name>" to serve as the storage for
the shm-based Lua dictionary "ngx.shared.<name>".
The "<size>" argument can take a size unit like "k" and "m". For
example,
http {
lua_shared_dict dogs 10m;
...
}
See ngx.shared.DICT for details.
This directive was first introduced in the "v0.3.1rc21" release.
Nginx API for Lua
The Nginx API exposed to the Lua land is provided in the form of two
standard packages "ngx" and "ndk". These packages are in the default
global scope.
When you're writing your own external Lua modules, however, you can
introduce these packages by using the package.seeall
(<http://www.lua.org/manual/5.1/manual.html#pdf-package.seeall>) option:
module("my_module", package.seeall)
function say(a) ngx.say(a) end
Alternatively, import them to your Lua modules by using file-scoped
local Lua variables, like this:
local ngx = ngx
module("my_module")
function say(a) ngx.say(a) end
You can directly require the standard packages "ngx" and "ndk"
introduced by this Nginx module, like this:
local ngx = require "ngx"
local ndk = require "ndk"
The ability to require these packages was introduced in the "v0.2.1rc19"
release.
Network I/O operations in user code should only be done through our
Nginx APIs defined below, otherwise Nginx event loop may be blocked and
performance may drop off dramatically. Small disk file operations can be
done via Lua's standard "io" and "file" libraries but should be
eliminated wherever possible because these also block the Nginx process.
Delegating all network and disk I/O operations to Nginx subrequests (via
the ngx.location.capture method and its friends) are strongly
recommended.
ngx.arg
syntax: *val = ngx.arg[index]*
context: *set_by_lua**
Index the input arguments to the set_by_lua and set_by_lua_file
directives:
value = ngx.arg[n]
Here's an example
location /foo {
set $a 32;
set $b 56;
set_by_lua $res
'return tonumber(ngx.arg[1]) + tonumber(ngx.arg[2])'
$a $b;
echo $sum;
}
that outputs 88, the sum of 32 and 56.
ngx.var.VARIABLE
syntax: *ngx.var.VAR_NAME*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua** value = ngx.var.some_nginx_variable_name
ngx.var.some_nginx_variable_name = value Note that you can only write to
nginx variables that are already defined. For example:
location /foo {
set $my_var ''; # this line is required to create $my_var at config time
content_by_lua '
ngx.var.my_var = 123;
...
';
}
That is, nginx variables cannot be created on-the-fly.
Some special nginx variables like $args and $limit_rate can be assigned
a value, some are not, like $arg_PARAMETER.
Nginx regex group capturing variables $1, $2, $3, and etc, can be read
by this interface as well, by writing "ngx.var[1]", "ngx.var[2]",
"ngx.var[3]", and etc.
Setting "nil" values to "ngx.var.Foo" will effectively make Nginx
variable $Foo undefined. For instance,
ngx.var.args = nil
Core constants
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
ngx.OK (0)
ngx.ERROR (-1)
ngx.AGAIN (-2)
ngx.DONE (-4)
They take the same values of "NGX_OK", "NGX_AGAIN", "NGX_DONE",
"NGX_ERROR", and etc. But now only ngx.exit only take two of these
values, i.e., "NGX_OK" and "NGX_ERROR".
HTTP method constants
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
ngx.HTTP_GET
ngx.HTTP_HEAD
ngx.HTTP_PUT
ngx.HTTP_POST
ngx.HTTP_DELETE
These constants are usually used in ngx.location.catpure and
ngx.location.capture_multi method calls.
HTTP status constants
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
value = ngx.HTTP_OK (200)
value = ngx.HTTP_CREATED (201)
value = ngx.HTTP_SPECIAL_RESPONSE (300)
value = ngx.HTTP_MOVED_PERMANENTLY (301)
value = ngx.HTTP_MOVED_TEMPORARILY (302)
value = ngx.HTTP_SEE_OTHER (303)
value = ngx.HTTP_NOT_MODIFIED (304)
value = ngx.HTTP_BAD_REQUEST (400)
value = ngx.HTTP_UNAUTHORIZED (401)
value = ngx.HTTP_FORBIDDEN (403)
value = ngx.HTTP_NOT_FOUND (404)
value = ngx.HTTP_NOT_ALLOWED (405)
value = ngx.HTTP_GONE (410)
value = ngx.HTTP_INTERNAL_SERVER_ERROR (500)
value = ngx.HTTP_METHOD_NOT_IMPLEMENTED (501)
value = ngx.HTTP_SERVICE_UNAVAILABLE (503)
Nginx log level constants
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
ngx.STDERR
ngx.EMERG
ngx.ALERT
ngx.CRIT
ngx.ERR
ngx.WARN
ngx.NOTICE
ngx.INFO
ngx.DEBUG
These constants are usually used by the ngx.log method.
print
syntax: *print(...)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Emit args concatenated to nginx's "error.log" file, with log level
"ngx.NOTICE" and prefix "lua print: ".
It's equivalent to
ngx.log(ngx.NOTICE, 'lua print: ', a, b, ...)
Lua "nil" arguments are accepted and result in literal "nil", and Lua
booleans result in "true" or "false".
ngx.ctx
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
This table can be used to store per-request context data for Lua
programmers.
This table has a liftime identical to the current request (just like
Nginx variables). Consider the following example,
location /test {
rewrite_by_lua '
ngx.say("foo = ", ngx.ctx.foo)
ngx.ctx.foo = 76
';
access_by_lua '
ngx.ctx.foo = ngx.ctx.foo + 3
';
content_by_lua '
ngx.say(ngx.ctx.foo)
';
}
Then "GET /test" will yield the output
foo = nil
79
That is, the "ngx.ctx.foo" entry persists across the rewrite, access,
and content phases of a request.
Also, every request has its own copy, include subrequests, for example:
location /sub {
content_by_lua '
ngx.say("sub pre: ", ngx.ctx.blah)
ngx.ctx.blah = 32
ngx.say("sub post: ", ngx.ctx.blah)
';
}
location /main {
content_by_lua '
ngx.ctx.blah = 73
ngx.say("main pre: ", ngx.ctx.blah)
local res = ngx.location.capture("/sub")
ngx.print(res.body)
ngx.say("main post: ", ngx.ctx.blah)
';
}
Then "GET /main" will give the output
main pre: 73
sub pre: nil
sub post: 32
main post: 73
We can see that modification of the "ngx.ctx.blah" entry in the
subrequest does not affect the one in its parent request. They do have
two separate versions of "ngx.ctx.blah" per se.
Internal redirection will destroy the original request's "ngx.ctx" data
(if any) and the new request will have an emptied "ngx.ctx" table. For
instance,
location /new {
content_by_lua '
ngx.say(ngx.ctx.foo)
';
}
location /orig {
content_by_lua '
ngx.ctx.foo = "hello"
ngx.exec("/new")
';
}
Then "GET /orig" will give you
nil
rather than the original "hello" value.
Arbitrary data values can be inserted into this "matic" table, including
Lua closures and nested tables. You can also register your own meta
methods with it.
Overriding "ngx.ctx" with a new Lua table is also supported, for
example,
ngx.ctx = { foo = 32, bar = 54 }
ngx.location.capture
syntax: *res = ngx.location.capture(uri, options?)*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
Issue a synchronous but still non-blocking *Nginx Subrequest* using
"uri".
Nginx subrequests provide a powerful way to make non-blocking internal
requests to other locations configured with disk file directory or *any*
other nginx C modules like "ngx_proxy", "ngx_fastcgi", "ngx_memc",
"ngx_postgres", "ngx_drizzle", and even "ngx_lua" itself and etc etc
etc.
Also note that subrequests just mimic the HTTP interface but there's
*no* extra HTTP/TCP traffic *nor* IPC involved. Everything works
internally, efficiently, on the C level.
Subrequests are completely different from HTTP 301/302 redirection (via
ngx.redirect) and internal redirection (via ngx.exec).
Here's a basic example:
res = ngx.location.capture(uri)
Returns a Lua table with three slots ("res.status", "res.header", and
"res.body").
"res.header" holds all the response headers of the subrequest and it is
a normal Lua table. For multi-value response headers, the value is a Lua
(array) table that holds all the values in the order that they appear.
For instance, if the subrequest response headers contains the following
lines:
Set-Cookie: a=3
Set-Cookie: foo=bar
Set-Cookie: baz=blah
Then "res.header["Set-Cookie"]" will be evaluted to the table value
"{"a=3", "foo=bar", "baz=blah"}".
URI query strings can be concatenated to URI itself, for instance,
res = ngx.location.capture('/foo/bar?a=3&b=4')
Named locations like @foo are not allowed due to a limitation in the
nginx core. Use normal locations combined with the "internal" directive
to prepare internal-only locations.
An optional option table can be fed as the second argument, which
support various options like "method", "body", "args", and
"share_all_vars". Issuing a POST subrequest, for example, can be done as
follows
res = ngx.location.capture(
'/foo/bar',
{ method = ngx.HTTP_POST, body = 'hello, world' }
)
See HTTP method constants methods other than POST. The "method" option
is "ngx.HTTP_GET" by default.
The "share_all_vars" option can control whether to share nginx variables
among the current request and the new subrequest. If this option is set
to "true", then the subrequest can see all the variable values of the
current request while the current requeset can also see any variable
value changes made by the subrequest. Note that variable sharing can
have unexpected side-effects and lead to confusing issues, use it with
special care. So, by default, the option is set to "false".
The "args" option can specify extra url arguments, for instance,
ngx.location.capture('/foo?a=1',
{ args = { b = 3, c = ':' } }
)
is equivalent to
ngx.location.capture('/foo?a=1&b=3&c=%3a')
that is, this method will automatically escape argument keys and values
according to URI rules and concatenating them together into a complete
query string. Because it's all done in hand-written C, it should be
faster than your own Lua code.
The "args" option can also take plain query string:
ngx.location.capture('/foo?a=1',
{ args = 'b=3&c=%3a' } }
)
This is functionally identical to the previous examples.
Note that, by default, subrequests issued by ngx.location.capture
inherit all the request headers of the current request. This may have
unexpected side-effects on the subrequest responses. For example, when
you're using the standard "ngx_proxy" module to serve your subrequests,
then an "Accept-Encoding: gzip" header in your main request may result
in gzip'd responses that your Lua code is not able to handle properly.
So always set proxy_pass_request_headers "off" in your subrequest
location to ignore the original request headers.
ngx.location.capture_multi
syntax: *res1, res2, ... = ngx.location.capture_multi({ {uri, options?},
{uri, options?}, ... })*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
Just like ngx.location.capture, but supports multiple subrequests
running in parallel.
This function issue several parallel subrequests specified by the input
table, and returns their results in the same order. For example,
res1, res2, res3 = ngx.location.capture_multi{
{ "/foo", { args = "a=3&b=4" } },
{ "/bar" },
{ "/baz", { method = ngx.HTTP_POST, body = "hello" } },
}
if res1.status == ngx.HTTP_OK then
...
end
if res2.body == "BLAH" then
...
end
This function will not return until all the subrequests terminate. The
total latency is the longest latency of the subrequests, instead of
their sum.
When you don't know inadvance how many subrequests you want to issue,
you can use Lua tables for both requests and responses. For instance,
-- construct the requests table
local reqs = {}
table.insert(reqs, { "/mysql" })
table.insert(reqs, { "/postgres" })
table.insert(reqs, { "/redis" })
table.insert(reqs, { "/memcached" })
-- issue all the requests at once and wait until they all return
local resps = { ngx.location.capture_multi(reqs) }
-- loop over the responses table
for i, resp in ipairs(resps) do
-- process the response table "resp"
end
The ngx.location.capture function is just a special form of this
function. Logically speaking, the ngx.location.capture can be
implemented like this
ngx.location.capture =
function (uri, args)
return ngx.location.capture_multi({ {uri, args} })
end
ngx.status
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Read and write the current request's response status. This should be
called before sending out the response headers.
ngx.status = ngx.HTTP_CREATED
status = ngx.status
ngx.header.HEADER
syntax: *ngx.header.HEADER = VALUE*
syntax: *value = ngx.header.HEADER*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
When assigning to "ngx.header.HEADER" will set, add, or clear the
current request's response header named "HEADER". Underscores ("_") in
the header names will be replaced by dashes ("-") and the header names
will be matched case-insensitively.
-- equivalent to ngx.header["Content-Type"] = 'text/plain'
ngx.header.content_type = 'text/plain';
ngx.header["X-My-Header"] = 'blah blah';
Multi-value headers can be set this way:
ngx.header['Set-Cookie'] = {'a=32; path=/', 'b=4; path=/'}
will yield
Set-Cookie: a=32; path=/
Set-Cookie: b=4; path=/
in the response headers. Only array-like tables are accepted.
Note that, for those standard headers that only accepts a single value,
like "Content-Type", only the last element in the (array) table will
take effect. So
ngx.header.content_type = {'a', 'b'}
is equivalent to
ngx.header.content_type = 'b'
Setting a slot to "nil" effectively removes it from the response
headers:
ngx.header["X-My-Header"] = nil;
same does assigning an empty table:
ngx.header["X-My-Header"] = {};
Setting "ngx.header.HEADER" after sending out response headers (either
explicitly with ngx.send_headers or implicitly with ngx.print and its
friends) will throw out a Lua exception.
Reading "ngx.header.HEADER" will return the value of the response header
named "HEADER". Underscores ("_") in the header names will also be
replaced by dashes ("-") and the header names will be matched
case-insensitively. If the response header is not present at all, "nil"
will be returned.
This is particularly useful in the context of filter_header_by_lua and
filter_header_by_lua_file, for example,
location /test {
set $footer '';
proxy_pass http://some-backend;
header_filter_by_lua '
if ngx.header["X-My-Header"] == "blah" then
ngx.var.footer = "some value"
end
';
echo_after_body $footer;
}
For multi-value headers, all of the values of header will be collected
in order and returned as a Lua table. For example, response headers
Foo: bar
Foo: baz
will result in
{"bar", "baz"}
to be returned when reading "ngx.header.Foo".
Note that "ngx.header" is not a normal Lua table so you cannot iterate
through it using Lua's "ipairs" function.
For reading *request* headers, use the ngx.req.get_headers function
instead.
ngx.req.set_uri
syntax: *ngx.req.set_uri(uri, jump?)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Rewrite the current request's (parsed) URI by the "uri" argument. The
"uri" argument must be a Lua string and cannot be of zero length, or a
Lua exception will be thrown.
The optional boolean "jump" argument can trigger location rematch (or
location jump) as [[HttpRewriteModule]]'s rewrite directive, that is,
when "jump" is "true" (default to "false"), this function will never
return and it will tell Nginx to try re-searching locations with the new
URI value at the later "post-rewrite" phase and jumping to the new
location. Location jump will not be triggered otherwise, and only the
current request's URI will be modified, which is also the default
behavior. This function will return but with no returned values when the
"jump" argument is "false" or absent altogether.
For example, the following nginx config snippet
rewrite ^ /foo last;
can be coded in Lua like this:
ngx.req.set_uri("/foo", true)
Similarly, Nginx config
rewrite ^ /foo break;
can be coded in Lua as
ngx.req.set_uri("/foo", false)
or equivalently,
ngx.req.set_uri("/foo")
The "jump" can only be set to "true" in rewrite_by_lua and
rewrite_by_lua_file. Use of jump in other contexts is prohibited and
will throw out a Lua exception.
A more sophisticated example involving regex substitutions is as follows
location /test {
rewrite_by_lua '
local uri = ngx.re.sub(ngx.var.uri, "^/test/(.*)", "$1", "o")
ngx.req.set_uri(uri)
';
proxy_pass http://my_backend;
}
which is functionally equivalent to
location /test {
rewrite ^/test/(.*) /$1 break;
proxy_pass http://my_backend;
}
Note that you cannot use this interface to rewrite URI arguments, and
you need to use ngx.req.set_uri_args for that. For instance, Nginx
config
rewrite ^ /foo?a=3? last;
can be coded as
ngx.req.set_uri_args("a=3")
ngx.req.set_uri("/foo", true)
or
ngx.req.set_uri_args({a = 3})
ngx.req.set_uri("/foo", true)
This interface was first introduced in the "v0.3.1rc14" release.
ngx.req.set_uri_args
syntax: *ngx.req.set_uri_args(args)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Rewrite the current request's URI query arguments by the "args"
argument. The "args" argument can be either a Lua string, as in
ngx.req.set_uri_args("a=3&b=hello%20world")
or a Lua table holding the query arguments' key-value pairs, as in
ngx.req.set_uri_args({ a = 3, b = "hello world" })
where in the latter case, this method will automatically escape argument
keys and values according to the URI escaping rule.
This interface was first introduced in the "v0.3.1rc13" release.
See also ngx.req.set_uri.
ngx.req.get_uri_args
syntax: *args = ngx.req.get_uri_args()*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Returns a Lua table holds all of the current request's request URL query
arguments.
Here's an example,
location = /test {
content_by_lua '
local args = ngx.req.get_uri_args()
for key, val in pairs(args) do
if type(val) == "table" then
ngx.say(key, ": ", table.concat(val, ", "))
else
ngx.say(key, ": ", val)
end
end
';
}
Then "GET /test?foo=bar&bar=baz&bar=blah" will yield the response body
foo: bar
bar: baz, blah
Multiple occurrences of an argument key will result in a table value
holding all of the values for that key in order.
Keys and values will be automatically unescaped according to URI
escaping rules. For example, in the above settings, "GET
/test?a%20b=1%61+2" will yield the output
a b: 1a 2
Arguments without the "=<value>" parts are treated as boolean arguments.
For example, "GET /test?foo&bar" will yield the outputs
foo: true
bar: true
That is, they will take Lua boolean values "true". However, they're
different from arguments taking empty string values. For example, "GET
/test?foo=&bar=" will give something like
foo:
bar:
Empty key arguments are discarded, for instance, "GET
/test?=hello&=world" will yield empty outputs.
Updating query arguments via the nginx variable $args (or "ngx.var.args"
in Lua) at runtime are also supported:
ngx.var.args = "a=3&b=42"
local args = ngx.req.get_uri_args()
Here the "args" table will always look like
{a = 3, b = 42}
regardless of the actual request query string.
ngx.req.get_post_args
syntax: *ngx.req.get_post_args()*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Returns a Lua table holds all of the current request's POST query
arguments. It's required to read the request body first by calling
ngx.req.read_body or to turn on the lua_need_request_body directive, or
a Lua exception will be thrown.
Here's an example,
location = /test {
content_by_lua '
ngx.req.read_body()
for key, val in pairs(args) do
if type(val) == "table" then
ngx.say(key, ": ", table.concat(val, ", "))
else
ngx.say(key, ": ", val)
end
end
';
}
Then
# Post request with the body 'foo=bar&bar=baz&bar=blah'
$ curl --data 'foo=bar&bar=baz&bar=blah' localhost/test
will yield the response body like
foo: bar
bar: baz, blah
Multiple occurrences of an argument key will result in a table value
holding all of the values for that key in order.
Keys and values will be automatically unescaped according to URI
escaping rules. For example, in the above settings,
# POST request with body 'a%20b=1%61+2'
$ curl -d 'a%20b=1%61+2' localhost/test
will yield the output
a b: 1a 2
Arguments without the "=<value>" parts are treated as boolean arguments.
For example, "GET /test?foo&bar" will yield the outputs
foo: true
bar: true
That is, they will take Lua boolean values "true". However, they're
different from arguments taking empty string values. For example, "POST
/test" with request body "foo=&bar=" will give something like
foo:
bar:
Empty key arguments are discarded, for instance, "POST /test" with body
"=hello&=world" will yield empty outputs.
ngx.req.get_headers
syntax: *headers = ngx.req.get_headers()*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Returns a Lua table holds all of the current request's request headers.
Here's an example,
local h = ngx.req.get_headers()
for k, v in pairs(h) do
...
end
To read an individual header:
ngx.say("Host: ", ngx.req.get_headers()["Host"])
For multiple instances of request headers like
Foo: foo
Foo: bar
Foo: baz
the value of "ngx.req.get_headers()["Foo"]" will be a Lua (array) table
like this:
{"foo", "bar", "baz"}
Another way to read individual request headers is to use
"ngx.var.http_HEADER", that is, nginx's standard $http_HEADER variables.
ngx.req.set_header
syntax: *ngx.req.set_header(header_name, header_value)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Set the current request's request header named "header_name" to value
"header_value", overriding any existing ones. None of the current
request's subrequests will be affected.
Here's an example of setting the "Content-Length" header:
ngx.req.set_header("Content-Type", "text/css")
The "header_value" can take an array list of values, for example,
ngx.req.set_header("Foo", {"a", "abc"})
will produce two new request headers:
Foo: a
Foo: abc
and old "Foo" headers will be overridden if there's any.
When the "header_value" argument is "nil", the request header will be
removed. So
ngx.req.set_header("X-Foo", nil)
is equivalent to
ngx.req.clear_header("X-Foo")
ngx.req.read_body
syntax: *ngx.req.read_body()*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
Read the client request body synchronously but still non-blockingly.
If the request body is already read previously by turning on
lua_need_request_body or by using other modules, then this function is a
no-op and returns immediately.
If the request body has already been explicitly discarded, either by
this module's ngx.req.discard_body or other modules, this function is a
no-op and returns immediately.
In case of errors, like connection errors while reading the data, this
method will throw out a Lua exception *or* terminate the current request
with the 500 status code immediately.
You can later either retrieve the request body data via
ngx.req.get_body_data or retrieve the temporary file name for the body
data cached to disk via ngx.req.get_body_file, depending on
1. whether the current request body is already exceeding your
client_body_buffer_size,
2. and whether you have turned on client_body_in_file_only.
In case that you do not want to read the request body and the current
request may have a request body, then it's crucial to use the
ngx.req.discard_body function to explicitly discard the request body, or
you'll break HTTP 1.1 keepalive and HTTP 1.1 pipelining.
Here's a small example:
ngx.req.read_body()
local args = ngx.req.get_post_args()
This function was first introduced in the "v0.3.1rc17" release.
ngx.req.discard_body
syntax: *ngx.req.discard_body()*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
Explicitly discard the request body, i.e., read the data on the
connection and throw it away immediately. Please note that, simply
ignoring request body is not the right way to discard it, you need to
call this function, or you'll break things under HTTP 1.1 keepalive or
HTTP 1.1 pipelining.
This function is an asynchronous call and returns immediately.
If the request body has already been read, this function does nothing
and returns immediately.
This function was first introduced in the "v0.3.1rc17" release.
See also ngx.req.read_body.
ngx.req.get_body_data
syntax: *data = ngx.req.get_body_data()*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
Retrieves the in-memory request body data. It returns a Lua string
rather than a Lua table holding all the parsed query arguments. If you
want the latter, use ngx.req.get_post_args instead.
This function returns "nil" if
1. the request body has not been read,
2. the request body has been read into disk temporary files,
3. or the request body has zero size.
If the request body has not been read yet, call ngx.req.read_body first
(or turned on lua_need_request_body to force this module to read the
request body automatically, but this is not recommended).
If the request body has been read into disk files, try calling the
ngx.req.get_body_file function instead.
In case that you want to enforce in-memory request bodies, try setting
client_body_buffer_size to the same size value in client_max_body_size.
Note that calling this function instead of using "ngx.var.request_body"
or "ngx.var.echo_request-body" is more efficient because it can save one
dynamic memory allocation and one data copy.
This function was first introduced in the "v0.3.1rc17" release.
See also ngx.req.get_body_file.
ngx.req.get_body_file
syntax: *file_name = ngx.req.get_body_file()*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
Retrieves the file name for the in-file request body data. Returns "nil"
if the request body has not been read or has been read into memory.
The returned file is read only and is usually cleaned up automatically
by Nginx's memory pool. It should not be modified, renamed, or removed
by your own Lua code.
If the request body has not been read yet, call ngx.req.read_body first
(or turned on lua_need_request_body to force this module to read the
request body automatically, but this is not recommended).
If the request body has been read into memory, try calling the
ngx.req.get_body_data function instead.
In case that you want to enforce in-file request bodies, try turning on
client_body_in_file_only.
This function was first introduced in the "v0.3.1rc17" release.
See also ngx.req.get_body_data.
ngx.req.set_body_data
syntax: *ngx.req.set_body_data(data)*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
Set the current request's request body using the in-memory data
specified by the "data" argument.
If the current request's request body has not been read, then it will be
properly discarded. When the current request's request body has been
read into memory or buffered into a disk file, then the old request
body's memory will be freed or the disk file will be cleaned up
immediately, respectively.
This function requires patching the Nginx core to function properly
because the Nginx core does not allow modifying request bodies by the
current design. Here is a patch for Nginx 1.0.8:
nginx-1.0.8-allow_request_body_updating.patch
(<https://github.com/agentzh/ngx_openresty/blob/master/patches/nginx-1.0
.8-allow_request_body_updating.patch>), and this patch should be applied
cleanly to other releases of Nginx as well.
If you're using ngx_openresty (<http://openresty.org/>) 1.0.8.17+, then
you've already had this patch applied.
This function was first introduced in the "v0.3.1rc18" release.
See also ngx.req.set_body_file.
ngx.req.set_body_file
syntax: *ngx.req.set_body_file(file_name, auto_clean?)*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
Set the current request's request body using the in-file data specified
by the "file_name" argument.
If the optional "auto_clean" argument is given a "true" value, then this
file will be automatically removed at request completion or the next
time this function or ngx.req.set_body_data are called in the same
request. The "auto_clean" is default to "false".
You must ensure that the file specified by the "file_name" argument
exists and is readable by an Nginx worker process by setting its
permission properly. Otherwise a Lua exception will be thrown.
If the current request's request body has not been read, then it will be
properly discarded. When the current request's request body has been
read into memory or buffered into a disk file, then the old request
body's memory will be freed or the disk file will be cleaned up
immediately, respectively.
This function requires patching the Nginx core to function properly
because the Nginx core does not allow modifying request bodies by the
current design. Here is a patch for Nginx 1.0.8:
nginx-1.0.8-allow_request_body_updating.patch
(<https://github.com/agentzh/ngx_openresty/blob/master/patches/nginx-1.0
.8-allow_request_body_updating.patch>), and this patch should be applied
cleanly to other releases of Nginx as well.
If you're using ngx_openresty (<http://openresty.org/>) 1.0.8.17+, then
you've already had this patch applied.
This function was first introduced in the "v0.3.1rc18" release.
See also ngx.req.set_body_data.
ngx.req.clear_header
syntax: *ngx.req.clear_header(header_name)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Clear the current request's request header named "header_name". None of
the current request's subrequests will be affected.
ngx.exec
syntax: *ngx.exec(uri, args?)*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
Does an internal redirect to "uri" with "args".
ngx.exec('/some-location');
ngx.exec('/some-location', 'a=3&b=5&c=6');
ngx.exec('/some-location?a=3&b=5', 'c=6');
Named locations are also supported, but query strings are ignored. For
example,
location /foo {
content_by_lua '
ngx.exec("@bar");
';
}
location @bar {
...
}
The optional second "args" can be used to specify extra URI query
arguments, for example:
ngx.exec("/foo", "a=3&b=hello%20world")
Alternatively, you can pass a Lua table for the "args" argument and let
ngx_lua do URI escaping and string concatenation automatically for you,
for instance,
ngx.exec("/foo", { a = 3, b = "hello world" })
The result is exactly the same as the previous example.
Note that this is very different from ngx.redirect in that it's just an
internal redirect and no new HTTP traffic is involved.
This method never returns.
This method *must* be called before ngx.send_headers or explicit
response body outputs by either ngx.print or ngx.say.
This method is very much like the echo_exec directive in
[[HttpEchoModule]].
ngx.redirect
syntax: *ngx.redirect(uri, status?)*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
Issue an "HTTP 301<code> or <code>302" redirection to "uri".
The optional "status" parameter specifies whether 301 or 302 to be used.
It's 302 ("ngx.HTTP_MOVED_TEMPORARILY") by default.
Here's a small example:
return ngx.redirect("/foo")
which is equivalent to
return ngx.redirect("http://localhost:1984/foo", ngx.HTTP_MOVED_TEMPORARILY)
assuming the current server name is "localhost" and it's listening on
the 1984 port.
This method *must* be called before ngx.send_headers or explicit
response body outputs by either ngx.print or ngx.say.
This method never returns.
This method is very much like the rewrite directive with the "redirect"
modifier in the standard [[HttpRewriteModule]], for example, this
"nginx.conf" snippet
rewrite ^ /foo? redirect; # nginx config
is equivalent to the following Lua code
return ngx.redirect('/foo'); -- lua code
while
rewrite ^ /foo? permanent; # nginx config
is equivalent to
return ngx.redirect('/foo', ngx.HTTP_MOVED_PERMANENTLY) -- Lua code
URI arguments can be specified as well, for example:
return ngx.redirect('/foo?a=3&b=4')
ngx.send_headers
syntax: *ngx.send_headers()*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
Explicitly send out the response headers.
Usually you don't have to send headers yourself. "ngx_lua" will
automatically send out headers right before you output contents via
ngx.say or ngx.print.
Headers will also be sent automatically when content_by_lua exits
normally.
ngx.headers_sent
syntax: *value = ngx.headers_sent*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Returns "true" if the response headers have been sent (by ngx_lua), and
"false" otherwise.
This API was first introduced in ngx_lua v0.3.1rc6.
ngx.print
syntax: *ngx.print(...)*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
Emit arguments concatenated to the HTTP client (as response body). If
response headers have not been sent yet, this function will first send
the headers out, and then output the body data.
Lua "nil" value will result in outputing "nil", and Lua boolean values
will emit literal "true" or "false", accordingly.
Also, nested arrays of strings are also allowed. The elements in the
arrays will be sent one by one. For example
local table = {
"hello, ",
{"world: ", true, " or ", false,
{": ", nil}}
}
ngx.print(table)
will yield the output
hello, world: true or false: nil
Non-array table arguments will cause a Lua exception to be thrown.
ngx.say
syntax: *ngx.say(...)*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
Just as ngx.print but also emit a trailing newline.
ngx.log
syntax: *ngx.log(log_level, ...)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Log arguments concatenated to error.log with the given logging level.
Lua "nil" arguments are accepted and result in literal "nil", and Lua
booleans result in literal "true" or "false" outputs.
The "log_level" argument can take constants like "ngx.ERR" and
"ngx.WARN". Check out Nginx log level constants for details.
ngx.flush
syntax: *ngx.flush()*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
Force flushing the response outputs. This operation has no effect in
HTTP 1.0 buffering output mode. See HTTP 1.0 support.
ngx.exit
syntax: *ngx.exit(status)*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
When "status >= 200" (i.e., "ngx.HTTP_OK" and above), it will interrupt
the execution of the current request and return status code to nginx.
When "status == 0" (i.e., "ngx.OK"), it will only quit the current phase
handler (or the content handler if the content_by_lua directive is used)
and continue to run laster phases (if any) for the current request.
The "status" argument can be "ngx.OK", "ngx.ERROR",
"ngx.HTTP_NOT_FOUND", "ngx.HTTP_MOVED_TEMPORARILY", or other HTTP status
constants.
To return an error page with custom contents, use code snippets like
this:
ngx.status = ngx.HTTP_GONE
ngx.say("This is our own content")
-- to cause quit the whole request rather than the current phase handler
ngx.exit(ngx.HTTP_OK)
The effect in action:
$ curl -i http://localhost/test
HTTP/1.1 410 Gone
Server: nginx/1.0.6
Date: Thu, 15 Sep 2011 00:51:48 GMT
Content-Type: text/plain
Transfer-Encoding: chunked
Connection: keep-alive
This is our own content
Number literals can be used directly as the argument, for instance,
ngx.exit(501)
ngx.eof
syntax: *ngx.eof()*
context: *rewrite_by_lua*, access_by_lua*, content_by_lua**
Explicitly specify the end of the response output stream.
ngx.escape_uri
syntax: *newstr = ngx.escape_uri(str)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Escape "str" as a URI component.
ngx.unescape_uri
syntax: *newstr = ngx.unescape_uri(str)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Unescape "str" as an escaped URI component.
ngx.encode_base64
syntax: *newstr = ngx.encode_base64(str)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Encode "str" to a base64 digest.
ngx.decode_base64
syntax: *newstr = ngx.decode_base64(str)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Decodes the "str" argument as a base64 digest to the raw form. Returns
"nil" if "str" is not well formed.
ngx.crc32_short
syntax: *intval = ngx.crc32_short(str)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Calculates the CRC-32 (Cyclic Redundancy Code) digest for the "str"
argument.
This method performs better on relatively short "str" inputs (i.e., less
than 30 ~ 60 bytes), as compared to ngx.crc32_long. The result is
exactly the same as ngx.crc32_long.
Behind the scene, it is just a thin wrapper around the "ngx_crc32_short"
function defined in the Nginx core.
This API was first introduced in the "v0.3.1rc8" release.
ngx.crc32_long
syntax: *intval = ngx.crc32_long(str)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Calculates the CRC-32 (Cyclic Redundancy Code) digest for the "str"
argument.
This method performs better on relatively long "str" inputs (i.e.,
longer than 30 ~ 60 bytes), as compared to ngx.crc32_short. The result
is exactly the same as ngx.crc32_short.
Behind the scene, it is just a thin wrapper around the "ngx_crc32_long"
function defined in the Nginx core.
This API was first introduced in the "v0.3.1rc8" release.
ngx.today
syntax: *str = ngx.today()*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Returns today's date (in the format "yyyy-mm-dd") from nginx cached time
(no syscall involved unlike Lua's date library).
This is the local time.
ngx.time
syntax: *secs = ngx.time()*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Returns the elapsed seconds from the epoch for the current timestamp
from the nginx cached time (no syscall involved unlike Lua's date
library).
ngx.localtime
syntax: *str = ngx.localtime()*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Returns the current timestamp (in the format "yyyy-mm-dd hh:mm:ss") of
the nginx cached time (no syscall involved unlike Lua's os.date
(<http://www.lua.org/manual/5.1/manual.html#pdf-os.date>) function).
This is the local time.
ngx.utctime
syntax: *str = ngx.utctime()*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Returns the current timestamp (in the format "yyyy-mm-dd hh:mm:ss") of
the nginx cached time (no syscall involved unlike Lua's os.date
(<http://www.lua.org/manual/5.1/manual.html#pdf-os.date>) function).
This is the UTC time.
ngx.cookie_time
syntax: *str = ngx.cookie_time(sec)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Returns a formated string can be used as the cookie expiration time. The
parameter "sec" is the timestamp in seconds (like those returned from
ngx.time).
ngx.say(ngx.cookie_time(1290079655))
-- yields "Thu, 18-Nov-10 11:27:35 GMT"
ngx.http_time
syntax: *str = ngx.http_time(sec)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Returns a formated string can be used as the http header time (for
example, being used in "Last-Modified" header). The parameter "sec" is
the timestamp in seconds (like those returned from ngx.time).
ngx.say(ngx.http_time(1290079655))
-- yields "Thu, 18 Nov 10 11:27:35 GMT"
ngx.parse_http_time
syntax: *sec = ngx.parse_http_time(str)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Parse the http time string (as returned by ngx.http_time) into seconds.
Returns the seconds or "nil" if the input string is in bad forms.
local time = ngx.parse_http_time("Thu, 18 Nov 10 11:27:35 GMT")
if time == nil then
...
end
ngx.is_subrequest
syntax: *value = ngx.is_subrequest*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Returns "true" if the current request is an nginx subrequest, or "false"
otherwise.
ngx.re.match
syntax: *captures = ngx.re.match(subject, regex, options?, ctx?)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Matches the "subject" string using the Perl-compatible regular
expression "regex" with the optional "options".
Only the first occurrence of the match is returned, or "nil" if no match
is found. In case of fatal errors, like seeing bad "UTF-8" sequences in
"UTF-8" mode, a Lua exception will be raised.
When a match is found, a Lua table "captures" is returned, where
"captures[0]" holds the whole substring being matched, and "captures[1]"
holds the first parenthesized subpattern's capturing, "captures[2]" the
second, and so on. Here's some examples:
local m = ngx.re.match("hello, 1234", "[0-9]+")
-- m[0] == "1234"
local m = ngx.re.match("hello, 1234", "([0-9])[0-9]+")
-- m[0] == "1234"
-- m[1] == "1"
Unmatched subpatterns will take "nil" values in their "captures" table
fields. For instance,
local m = ngx.re.match("hello, world", "(world)|(hello)")
-- m[0] == "hello"
-- m[1] == nil
-- m[2] == "hello"
Escaping sequences in Perl-compatible regular expressions like "\d",
"\s", and "\w", require special care when specifying them in Lua string
literals, because the backslash character, "\", needs to be escaped in
Lua string literals too, for example,
? m = ngx.re.match("hello, 1234", "\d+")
won't work as expected and won't match at all. Intead, you should escape
the backslash itself and write
m = ngx.re.match("hello, 1234", "\\d+")
When you put the Lua code snippet in your "nginx.conf" file, you have to
escape the backslash one more time, because your Lua code is now in an
nginx string literal, and backslashes in nginx string literals require
escaping as well. For instance,
location /test {
content_by_lua '
local m = ngx.re.match("hello, 1234", "\\\\d+")
if m then ngx.say(m[0]) else ngx.say("not matched!") end
';
}
You can also specify "options" to control how the match will be
performed. The following option characters are supported:
a anchored mode (only match from the beginning)
i caseless mode (just like Perl's /i modifier)
m multi-line mode (just like Perl's /m modifier)
o compile-once mode (similar to Perl's /o modifer),
to enable the worker-process-level compiled-regex cache
s single-line mode (just like Perl's /s modifier)
u UTF-8 mode
x extended mode (just like Perl's /x modifier)
These characters can be combined together, for example,
local m = ngx.re.match("hello, world", "HEL LO", "ix")
-- m[0] == "hello"
local m = ngx.re.match("hello, 美好生活", "HELLO, (.{2})", "iu")
-- m[0] == "hello, 美好"
-- m[1] == "美好"
The "o" regex option is good for performance tuning, because the regex
in question will only be compiled once, cached in the worker-process
level, and shared among all the requests in the current Nginx worker
process. You can tune the upper limit of the regex cache via the
lua_regex_cache_max_entries directive.
The optional fourth argument, "ctx", can be a Lua table holding an
optional "pos" field. When the "pos" field in the "ctx" table argument
is specified, "ngx.re.match" will start matching from that offset.
Regardless of the presence of the "pos" field in the "ctx" table,
"ngx.re.match" will always set this "pos" field to the position *after*
the substring matched by the whole pattern in case of a successful
match. When match fails, the "ctx" table will leave intact. Here is some
examples,
local ctx = {}
local m = ngx.re.match("1234, hello", "[0-9]+", "", ctx)
-- m[0] = "1234"
-- ctx.pos == 4
local ctx = { pos = 2 }
local m = ngx.re.match("1234, hello", "[0-9]+", "", ctx)
-- m[0] = "34"
-- ctx.pos == 4
The "ctx" table argument combined with the "a" regex modifier can be
used to construct a lexer atop "ngx.re.match".
Note that, the "options" argument is not optional when the "ctx"
argument is specified; use the empty Lua string ("") as the placeholder
for "options" if you do not want to specify any regex options.
This method requires the PCRE library enabled in your Nginx build.
This feature is introduced in the "v0.2.1rc11" release.
ngx.re.gmatch
syntax: *iterator = ngx.re.gmatch(subject, regex, options?)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Similar to ngx.re.match, but returns a Lua iterator instead, so as to
let the user programmer iterate all the matches over the "<subject>"
string argument with the Perl-compatible regular expression "regex".
Here's a small exmple to demonstrate its basic usage:
local iterator = ngx.re.gmatch("hello, world!", "([a-z]+)", "i")
local m
m = iterator() -- m[0] == m[1] == "hello"
m = iterator() -- m[0] == m[1] == "world"
m = iterator() -- m == nil
More often we just put it into a Lua "for" loop:
for m in ngx.re.gmatch("hello, world!", "([a-z]+)", "i")
ngx.say(m[0])
ngx.say(m[1])
end
The optional "options" argument takes exactly the same semantics as the
ngx.re.match method.
The current implementation requires that the iterator returned should
only be used in a single request. That is, one should *not* assign it to
a variable belonging to persistent namespace like a Lua package.
This method requires the PCRE library enabled in your Nginx build.
This feature was first introduced in the "v0.2.1rc12" release.
ngx.re.sub
syntax: *newstr, n = ngx.re.sub(subject, regex, replace, options?)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Substitutes the first match of the Perl-compatible regular expression
"regex" on the "subject" argument string with the string or function
argument "replace". The optional "options" argument has exactly the same
meaning as in ngx.re.match.
This method returns the resulting new string as well as the number of
successful substitutions, or throw out a Lua exception when an error
occurred (syntax errors in the "<replace>" string argument, for
example).
When the "replace" is a string, then it is treated as a special template
for string replacement. For example,
local newstr, n = ngx.re.sub("hello, 1234", "([0-9])[0-9]", "[$0][$1]")
-- newstr == "hello, [12][1]34"
-- n == 1
where $0 referring to the whole substring matched by the pattern and $1
referring to the first parenthesized capturing substring.
You can also use curly braces to disambiguate variable names from the
background string literals:
local newstr, n = ngx.re.sub("hello, 1234", "[0-9]", "${0}00")
-- newstr == "hello, 10034"
-- n == 1
Literal dollar sign characters ("$") in the "replace" string argument
can be escaped by another dollar sign, for instance,
local newstr, n = ngx.re.sub("hello, 1234", "[0-9]", "$$")
-- newstr == "hello, $234"
-- n == 1
Do not use backlashes to escape dollar signs; it won't work as expected.
When the "replace" argument is of type "function", then it will be
invoked with the "match table" as the argument to generate the replace
string literal for substitution. The "match table" fed into the
"replace" function is exactly the same as the return value of
ngx.re.match. Here is an example:
local func = function (m)
return "[" .. m[0] .. "][" .. m[1] .. "]"
end
local newstr, n = ngx.re.sub("hello, 1234", "( [0-9] ) [0-9]", func, "x")
-- newstr == "hello, [12][1]34"
-- n == 1
The dollar sign characters in the return value of the "replace" function
argument are not special at all.
This method requires the PCRE library enabled in your Nginx build.
This feature was first introduced in the "v0.2.1rc13" release.
ngx.re.gsub
syntax: *newstr, n = ngx.re.gsub(subject, regex, replace, options?)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Just like ngx.re.sub, but does global substitution.
Here is some examples:
local newstr, n = ngx.re.gsub("hello, world", "([a-z])[a-z]+", "[$0,$1]", "i")
-- newstr == "[hello,h], [world,w]"
-- n == 2
local func = function (m)
return "[" .. m[0] .. "," .. m[1] .. "]"
end
local newstr, n = ngx.re.gsub("hello, world", "([a-z])[a-z]+", func, "i")
-- newstr == "[hello,h], [world,w]"
-- n == 2
This method requires the PCRE library enabled in your Nginx build.
This feature was first introduced in the "v0.2.1rc15" release.
ngx.shared.DICT
syntax: *dict = ngx.shared.DICT*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Fetching the shm-based Lua dictionary object for the shared memory zone
named "DICT" defined by the lua_shared_dict directive.
The resulting object "dict" has the following methods:
* get
* set
Here is an example:
http {
lua_shared_dict dogs 10m;
server {
location /set {
content_by_lua '
local dogs = ngx.shared.dogs
dogs:set("Jim", 8)
ngx.say("STORED")
';
}
location /get {
content_by_lua '
local dogs = ngx.shared.dogs
ngx.say(dogs:get("Jim"))
';
}
}
}
Let's test it:
$ curl localhost/set
STORED
$ curl localhost/get
8
$ curl localhost/get
8
You will consistently get the output 8 when accessing "/get" regardless
how many Nginx workers there are because the "dogs" dictionary resides
in the shared memory and visible to *all* of the worker processes.
The shared dictionary will retain its contents through a server config
reload (either by means of the "HUP" signal or by the "-s reload"
command-line option).
This feature was first introduced in the "v0.3.1rc21" release.
ngx.shared.DICT.get
syntax: *value = ngx.shared.DICT:get(key)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Retrieving the value in the dictionary ngx.shared.DICT for the key
"key". If the key does not exist or has been expired, then "nil" will be
returned.
The value returned will have the original data type when they were
inserted into the dictionary, for example, Lua booleans, numbers, or
strings.
The first argument to this method must be the dictionary object itself,
for example,
local cats = ngx.shared.cats
local value = cats.get(cats, "Marry")
or use Lua's syntactic sugar for method calls:
local cats = ngx.shared.cats
local value = cats:get("Marry")
These two forms are fundamentally equivalent.
This feature was first introduced in the "v0.3.1rc21" release.
See also ngx.shared.DICT.set.
ngx.shared.DICT.set
syntax: *forcible = ngx.shared.DICT:set(key, value, exptime?)*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
Setting the value in the dictionary ngx.shared.DICT for the key "key".
Returns a boolean value to indicate whether other valid items have been
removed forcibly when out of storage in the shared memory zone.
The value inserted can be Lua booleans, numbers, strings, or "nil".
Their value type will also be stored into the dictionary, thus you can
get exactly the same data type when later retrieving the value out of
the dictionary via the get method.
The optional "exptime" argument specifies expiration time (in seconds)
for the inserted key-value pair. The time resolution is 0.001 seconds.
If the "exptime" takes the value 0 (which is the default), then the item
will never be expired.
When it fails to allocate memory for the current key-value item, then
"set" will try removing existing items in the storage according to the
Least-Recently Used (LRU) algorithm. Note that, LRU takes priority over
expiration time here. If up to tens of existing items have been removed
and the storage left is still insufficient (either due to the total
capacity limit specified by lua_shared_dict or memory segmentation),
then a Lua exception will be thrown).
If this method succeeds in storing the current item by forcibly removing
other not-yet-expired items in the dictionary via LRU, it will return
the "true" value. If it stores the item without forcibly removing other
valid items, then "false" will be returned.
The first argument to this method must be the dictionary object itself,
for example,
local cats = ngx.shared.cats
cats.set(cats, "Marry", "it is a nice cat!")
or use Lua's syntactic sugar for method calls:
local cats = ngx.shared.cats
cats:set("Marry", "it is a nice cat!")
These two forms are fundamentally equivalent.
This feature was first introduced in the "v0.3.1rc21" release.
See also ngx.shared.DICT.get.
ndk.set_var.DIRECTIVE
syntax: *res = ndk.set_var.DIRECTIVE_NAME*
context: *set_by_lua*, rewrite_by_lua*, access_by_lua*, content_by_lua*,
header_filter_by_lua**
This mechanism allows calling other nginx C modules' directives that are
implemented by Nginx Devel Kit
(<https://github.com/simpl/ngx_devel_kit>) (NDK)'s set_var submodule's
"ndk_set_var_value".
For example, [[HttpSetMiscModule]]'s following directives can be invoked
this way:
* set_quote_sql_str
* set_quote_pgsql_str
* set_quote_json_str
* set_unescape_uri
* set_escape_uri
* set_encode_base32
* set_decode_base32
* set_encode_base64
* set_decode_base64
* set_encode_hex
* set_decode_hex
* set_sha1
* set_md5
For instance,
local res = ndk.set_var.set_escape_uri('a/b');
-- now res == 'a%2fb'
Similarly, the following directives provided by
[[HttpEncryptedSessionModule]] can be invoked from within Lua too:
* set_encrypt_session
* set_decrypt_session
This feature requires the ngx_devel_kit
(<https://github.com/simpl/ngx_devel_kit>) module.
HTTP 1.0 support
The HTTP 1.0 protocol does not support chunked outputs and always
requires an explicit "Content-Length" header when the response body is
non-empty. So when an HTTP 1.0 request is present, This module will
automatically buffer all the outputs of user calls of ngx.say and
ngx.print and postpone sending response headers until it sees all the
outputs in the response body, and at that time ngx_lua can calculate the
total length of the body and construct a proper "Content-Length" header
for the HTTP 1.0 client.
Note that, common HTTP benchmark tools like "ab" and "http_load" always
issue HTTP 1.0 requests by default. To force "curl" to send HTTP 1.0
requests, use the -0 option.
Data Sharing within an Nginx Worker
NOTE: This mechanism behaves differently when code cache is turned off,
and should be considered as a DIRTY TRICK. Backward compatibility is NOT
guaranteed. Use at your own risk! We're going to design a whole new
data-sharing mechanism.
If you want to globally share user data among all the requests handled
by the same nginx worker process, you can encapsulate your shared data
into a Lua module, require the module in your code, and manipulate
shared data through it. It works because required Lua modules are loaded
only once, and all coroutines will share the same copy of the module.
Here's a complete small example:
-- mydata.lua
module("mydata", package.seeall)
local data = {
dog = 3,
cat = 4,
pig = 5,
}
function get_age(name)
return data[name]
end
and then accessing it from your nginx.conf:
location /lua {
content_lua_by_lua '
local mydata = require("mydata")
ngx.say(mydata.get_age("dog"))
';
}
Your "mydata" module in this example will only be loaded and run on the
first request to the location "/lua", and all those subsequent requests
to the same nginx worker process will use the reloaded instance of the
module as well as the same copy of the data in it, until you send a
"HUP" signal to the nginx master process to enforce a reload.
This data sharing technique is essential for high-performance Lua apps
built atop this module. It's common to cache reusable data globally.
It's worth noting that this is *per-worker* sharing, not *per-server*
sharing. That is, when you have multiple nginx worker processes under an
nginx master, this data sharing cannot pass process boundary. If you
indeed need server-wide data sharing, you can
1. Use only a single nginx worker and a single server. This is not
recommended when you have a multi-core CPU or multiple CPUs in a
single machine.
2. Use some true backend storage like "memcached", "redis", or an RDBMS
like "mysql".
Performance
The Lua state (aka the Lua vm instance) is shared across all the
requests handled by a single nginx worker process to miminize memory
use.
On a ThinkPad T400 2.80 GHz laptop, it's easy to achieve 25k req/sec
using ab w/o keepalive and 37k+ req/sec with keepalive.
You can get better performance when building this module with LuaJIT
2.0.
Typical Use Cases
Just to name a few:
* Mashup'ing and processing outputs of various nginx upstream outputs
(proxy, drizzle, postgres, redis, memcached, and etc) in Lua,
* doing arbitrarily complex access control and security checks in Lua
before requests actually reach the upstream backends,
* manipulating response headers in an arbitrary way (by Lua)
* fetching backend information from external storage backends (like
redis, memcached, mysql, postgresql) and use that information to
choose which upstream backend to access on-the-fly,
* coding up arbitrarily complex web applications in a content handler
using synchronous but still non-blocking access to the database
backends and other storage,
* doing very complex URL dispatch in Lua at rewrite phase,
* using Lua to implement advanced caching mechanism for nginx
subrequests and arbitrary locations.
Actually the possibilities are unlimited, the Lua language is plays the
role of glueing existing stuffs in Nginx.
This module gives the flexibility of scripting but also offers
performance comparable with C (in terms of both CPU time and memory
footprint), especially when LuaJIT 2.0 is enabled, which other scripting
language implementations are hard to catch up.
Installation
You're recommended to install this module as well as the Lua interpreter
or LuaJIT 2.0 (with many other good stuffs) via the ngx_openresty
bundle:
http://openresty.org
The installation steps are usually as simple as "./configure && make &&
make install".
Alternatively, you can compile this module with nginx core's source by
hand:
1. Install Lua or LuaJIT into your system. At least Lua 5.1 is
required. Lua can be obtained freely from its project homepage
(<http://www.lua.org/>). For Ubuntu/Debian users, just install the
liblua5.1-0-dev package (or something like that).
2. Download the latest version of the release tarball of the
ngx_devel_kit (NDK) module from lua-nginx-module file list
(<http://github.com/simpl/ngx_devel_kit/tags>).
3. Download the latest version of the release tarball of this module
from lua-nginx-module file list
(<http://github.com/chaoslawful/lua-nginx-module/tags>).
4. Grab the nginx source code from nginx.org (<http://nginx.org/>), for
example, the version 1.0.5 (see nginx compatibility), and then build
the source with this module:
wget 'http://nginx.org/download/nginx-1.0.5.tar.gz'
tar -xzvf nginx-1.0.5.tar.gz
cd nginx-1.0.5/
# tell nginx's build system where to find lua:
export LUA_LIB=/path/to/lua/lib
export LUA_INC=/path/to/lua/include
# or tell where to find LuaJIT when you want to use JIT instead
# export LUAJIT_LIB=/path/to/luajit/lib
# export LUAJIT_INC=/path/to/luajit/include/luajit-2.0
# Here we assume you would install you nginx under /opt/nginx/.
./configure --prefix=/opt/nginx \
--add-module=/path/to/ngx_devel_kit \
--add-module=/path/to/lua-nginx-module
make -j2
make install
Compatibility
The following versions of Nginx should work with this module:
*
1.1.x (last tested: 1.1.5)
*
1.0.x (last tested: 1.0.8)
*
0.9.x (last tested: 0.9.4)
*
0.8.x >= 0.8.54 (last tested: 0.8.54)
Earlier versions of Nginx like 0.6.x and 0.5.x will not work.
If you find that any particular version of Nginx above 0.8.54 does not
work with this module, please consider reporting a bug.
Report Bugs
Although a lot of effort has been put into testing and code tuning,
there must be some serious bugs lurking somewhere in this module. So
whenever you are bitten by any quirks, please don't hesitate to
1. create a ticket on the issue tracking interface
(<http://github.com/chaoslawful/lua-nginx-module/issues>) provided
by GitHub,
2. or send a bug report or even patches to the nginx mailing list
(<http://mailman.nginx.org/mailman/listinfo/nginx>).
Source Repository
Available on github at chaoslawful/lua-nginx-module
(<http://github.com/chaoslawful/lua-nginx-module>).
Test Suite
To run the test suite, you also need the following dependencies:
* Nginx version >= 0.8.54
* Perl modules:
* test-nginx: http://github.com/agentzh/test-nginx
* Nginx modules:
* echo-nginx-module: http://github.com/agentzh/echo-nginx-module
* drizzle-nginx-module:
http://github.com/chaoslawful/drizzle-nginx-module
* rds-json-nginx-module:
http://github.com/agentzh/rds-json-nginx-module
* set-misc-nginx-module:
http://github.com/agentzh/set-misc-nginx-module
* headers-more-nginx-module:
http://github.com/agentzh/headers-more-nginx-module
* memc-nginx-module: http://github.com/agentzh/memc-nginx-module
* srcache-nginx-module:
http://github.com/agentzh/srcache-nginx-module
* ngx_auth_request:
http://mdounin.ru/hg/ngx_http_auth_request_module/
* C libraries:
* yajl: https://github.com/lloyd/yajl
* Lua modules:
* lua-yajl: https://github.com/brimworks/lua-yajl
* Note: the compiled module has to be placed in
'/usr/local/lib/lua/5.1/'
* Applications:
* mysql: create database 'ngx_test', grant all privileges to user
'ngx_test', password is 'ngx_test'
* memcached
These module's adding order is IMPORTANT! For filter modules's position
in filtering chain affects a lot. The correct configure adding order is:
1. ngx_devel_kit
2. set-misc-nginx-module
3. ngx_http_auth_request_module
4. echo-nginx-module
5. memc-nginx-module
6. lua-nginx-module (i.e. this module)
7. headers-more-nginx-module
8. srcache-nginx-module
9. drizzle-nginx-module
10. rds-json-nginx-module
TODO
* add "ignore_resp_headers", "ignore_resp_body", and "ignore_resp"
options to ngx.location.capture and ngx.location.capture_multi`
methods, to allow micro performance tuning on the user side.
* add directives to run lua codes when nginx stops/reloads.
* deal with TCP 3-second delay problem under great connection harness.
* add options to ngx.location.capture and ngx.location.capture_multi
in order to share and copy a particular set of nginx variables with
subrequests, specified by the user.
* add an option to ngx.location.capture and ngx.location.capture_multi
so as to specify the ngx.ctx table for subrequests.
* expose nginx's shared memory facility to the Lua land.
* add support for multi-value arguments to [[#ngx.req.set_uri_args]]
if its "args" argument is a Lua table.
Future Plan
* add the "lua_require" directive to load module into main thread's
globals.
* add the "cosocket" mechamism that will emulate a common set of Lua
socket API that will give you totally transparently non-blocking
capability out of the box by means of a completely new upstream
layer atop the nginx event model and no nginx subrequest overheads.
* add Lua code automatic time slicing support by yielding and resuming
the Lua VM actively via Lua's debug hooks.
* make set_by_lua using the same mechanism as content_by_lua.
* add coroutine API back to the Lua land.
Known Issues
* As ngx_lua's predefined Nginx I/O APIs use coroutine
yielding/resuming mechanism, the user code should not call any Lua
modules that use coroutine API to prevent obfuscating the predefined
Nginx APIs like ngx.location.capture (actually coroutine modules
have been masked off in content_by_lua directives and others). This
limitation is a little crucial, but don't worry, we're working on an
alternative coroutine implementation that can fit into the Nginx
event model. When it is done, the user code will be able to use the
Lua coroutine mechanism freely as in standard Lua again!
* Lua's "dofile" builtin is implemented as a C function in both Lua
5.1 and LuaJIT 2.0. And when you call ngx.location.capture,
ngx.exec, ngx.exit or ngx.req.read_body or something like those in
the .lua file to be loaded, it'll effectively initiate a coroutine
yield and that yield will run across C function boundary, which is
disallowed, and usually result in error messages like "lua handler
aborted: runtime error: attempt to yield across C-call boundary".
You should use Lua's "require" builtin instead.
* Because the standard Lua 5.1 interpreter's VM is not fully
resumable, the methods ngx.location.capture,
ngx.location.capture_multi, ngx.redirect, ngx.exec, and ngx.exit
cannot be used within the context of a Lua pcall()
(<http://www.lua.org/manual/5.1/manual.html#pdf-pcall>) or xpcall()
(<http://www.lua.org/manual/5.1/manual.html#pdf-xpcall>) when the
standard Lua 5.1 interpreter is used; you'll get the error "attempt
to yield across metamethod/C-call boundary". To fix this, please use
LuaJIT 2.0 instead, because LuaJIT 2.0 supports a fully resume-able
VM.
* The ngx.location.capture and ngx.location.capture_multi Lua methods
cannot capture locations configured by [[HttpEchoModule]]'s
echo_location, echo_location_async, echo_subrequest, or
echo_subrequest_async directives. This won't be fixed in the future
due to technical problems.
* WATCH OUT: Globals WON'T persist between requests, because of the
one-coroutine-per-request isolation design. Especially watch
yourself when using "require()" to import modules, and use this
form:
local xxx = require('xxx')
instead of the old deprecated form: require('xxx')
The old form will cause module unusable in requests for the reason told previously. If you have to stick with the old form, you can always force loading module for every request by clean C<< package.loaded.<module> >>, like this: package.loaded.xxx = nil
require('xxx')
* It's recommended to always put the following piece of code at the
end of your Lua modules using ngx.location.capture or
ngx.location.capture_multi to prevent casual use of module-level
global variables that are shared among *all* requests, which is
usually not what you want:
getmetatable(foo.bar).__newindex = function (table, key, val)
error('Attempt to write to undeclared variable "' .. key .. '": '
.. debug.traceback())
end
assuming your current Lua module is named C<foo.bar>. This will guarantee that you have declared your Lua functions' local Lua variables as "local" in your Lua modules, or bad race conditions while accessing these variables under load will tragically happen. See the C<Data Sharing within an Nginx Worker> for the reasons of this danger.
Changes
v0.3.0
New features
* added the header_filter_by_lua and header_filter_by_lua_file
directives. thanks Liseen Wan (万珣新).
* implemented the PCRE regex API for Lua: ngx.re.match, ngx.re.gmatch,
ngx.re.sub, and ngx.re.gsub.
* now we add the "ngx" and "ndk" table into "package.loaded" such that
the user can write "local ngx = require 'ngx'" and "local ndk =
require 'ndk'". thanks @Lance.
* added new directive lua_regex_cache_max_entries to control the upper
limit of the worker-process-level compiled-regex cache enabled by
the "o" regex option.
* implemented the special ngx.ctx Lua table for user programmers to
store per-request Lua context data for their applications. thanks
欧远宁 for suggesting this feature.
* now ngx.print and ngx.say allow (nested) array-like table arguments.
the array elements in them will be sent piece by piece. this will
avoid string concatenation for templating engines like ltp
(<http://www.savarese.com/software/ltp/>).
* implemented the ngx.req.get_post_args method for fetching
url-encoded POST query arguments from within Lua.
* implemented the ngx.req.get_uri_args method to fetch parsed URL
query arguments from within Lua. thanks Bertrand Mansion (golgote).
* added new function ngx.parse_http_time, thanks James Hurst.
* now we allow Lua boolean and "nil" values in arguments to ngx.say,
ngx.print, ngx.log and print.
* added support for user C macros "LUA_DEFAULT_PATH" and
"LUA_DEFAULT_CPATH". for now we can only define them in "ngx_lua"'s
"config" file because nginx "configure"'s "--with-cc-opt" option
hates values with double-quotes in them. sigh. ngx_openresty
(<http://openresty.org/>) is already using this feature to bundle
3rd-party Lua libraries.
Bug fixes
* worked-around the "stack overflow" issue while using
"luarocks.loader" and disabling lua_code_cache, as described as
github issue #27. thanks Patrick Crosby.
* fixed the "zero size buf in output" alert while combining
lua_need_request_body on + access_by_lua/rewrite_by_lua +
proxy_pass/fastcgi_pass. thanks Liseen Wan (万珣新).
* fixed issues with HTTP 1.0 HEAD requests.
* made setting "ngx.header.HEADER" after sending out response headers
throw out a Lua exception to help debugging issues like github issue
#49. thanks Bill Donahue (ikhoyo).
* fixed an issue regarding defining global variables in C header
files: we should have defined the global "ngx_http_lua_exception" in
a single compilation unit. thanks @姜大炮.
Authors
* chaoslawful (王晓哲) <chaoslawful at gmail dot com>
* Zhang "agentzh" Yichun (章亦春) <agentzh at gmail dot com>
Copyright & License
This module is licenced under the BSD license.
Copyright (C) 2009, 2010, 2011, by Xiaozhe Wang (chaoslawful)
<chaoslawful@gmail.com>.
Copyright (C) 2009, 2010, 2011, by Zhang "agentzh" Yichun (章亦春)
<agentzh@gmail.com>.
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
See Also
* Dynamic Routing Based on Redis and Lua
(<http://openresty.org/#DynamicRoutingBasedOnRedis>)
* Using LuaRocks with ngx_lua (<http://openresty.org/#UsingLuaRocks>)
* Introduction to ngx_lua
(<https://github.com/chaoslawful/lua-nginx-module/wiki/Introduction>
)
* ngx_devel_kit (<http://github.com/simpl/ngx_devel_kit>)
* [[HttpEchoModule]]
* [[HttpDrizzleModule]]
* postgres-nginx-module (<http://github.com/FRiCKLE/ngx_postgres>)
* [[HttpMemcModule]]
* The ngx_openresty bundle (<http://openresty.org>)
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