support for `docker run` environment variables file

Docker-DCO-1.1-Signed-off-by: Vincent Batts <vbatts@redhat.com> (github: vbatts)

docs/sources/reference/commandline/cli.rst

@@ -1152,6 +1152,7 @@ image is removed.
       --cidfile="": Write the container ID to the file
       -d, --detach=false: Detached mode: Run container in the background, print new container id
       -e, --env=[]: Set environment variables
+      --envfile="": Read in a line delimited file of ENV variables
       -h, --hostname="": Container host name
       -i, --interactive=false: Keep stdin open even if not attached
       --privileged=false: Give extended privileges to this container
@@ -1284,6 +1285,17 @@ This exposes port ``80`` of the container for use within a link without
 publishing the port to the host system's interfaces. :ref:`port_redirection`
 explains in detail how to manipulate ports in Docker.
 
+.. code-block:: bash
+
+    $ sudo docker run -e MYVAR1 --env MYVAR2=foo --envfile ./env.list ubuntu bash
+
+This sets environmental variables to the container. For illustration all three
+flags are shown here. Where -e and --env can be repeated, take an environment 
+variable and value, or if no "=" is provided, then that variable's current
+value is passed through (i.e. $MYVAR1 from the host is set to $MYVAR1 in the
+container). The --envfile flag takes a filename as an argument and expects each
+line to be a VAR=VAL format.
+
 .. code-block:: bash
 
     $ sudo docker run --name console -t -i ubuntu bash

pkg/opts/envfile.go

@@ -0,0 +1,44 @@
+package opts
+
+import (
+	"bufio"
+	"bytes"
+	"io"
+	"os"
+)
+
+/*
+Read in a line delimited file with environment variables enumerated
+*/
+func ParseEnvFile(filename string) ([]string, error) {
+	fh, err := os.Open(filename)
+	if err != nil {
+		return []string{}, err
+	}
+	var (
+		lines       []string = []string{}
+		line, chunk []byte
+	)
+	reader := bufio.NewReader(fh)
+	line, isPrefix, err := reader.ReadLine()
+
+	for err == nil {
+		if isPrefix {
+			chunk = append(chunk, line...)
+		} else if !isPrefix && len(chunk) > 0 {
+			line = chunk
+			chunk = []byte{}
+		} else {
+			chunk = []byte{}
+		}
+
+		if !isPrefix && len(line) > 0 && bytes.Contains(line, []byte("=")) {
+			lines = append(lines, string(line))
+		}
+		line, isPrefix, err = reader.ReadLine()
+	}
+	if err != nil && err != io.EOF {
+		return []string{}, err
+	}
+	return lines, nil
+}

runconfig/parse.go

@@ -68,6 +68,7 @@ func parseRun(cmd *flag.FlagSet, args []string, sysInfo *sysinfo.SysInfo) (*Conf
 		flWorkingDir      = cmd.String([]string{"w", "-workdir"}, "", "Working directory inside the container")
 		flCpuShares       = cmd.Int64([]string{"c", "-cpu-shares"}, 0, "CPU shares (relative weight)")
 		flLabelOptions    = cmd.String([]string{"Z", "-label"}, "", "Options to pass to underlying labeling system")
+		flEnvFile         = cmd.String([]string{"#envfile", "-envfile"}, "", "Read in a line delimited file of ENV variables")
 
 		// For documentation purpose
 		_ = cmd.Bool([]string{"#sig-proxy", "-sig-proxy"}, true, "Proxify all received signal to the process (even in non-tty mode)")
@@ -199,6 +200,17 @@ func parseRun(cmd *flag.FlagSet, args []string, sysInfo *sysinfo.SysInfo) (*Conf
 		}
 	}
 
+	// collect all the environment variables for the container
+	envVariables := []string{}
+	envVariables = append(envVariables, flEnv.GetAll()...)
+	parsedVars, err := opts.ParseEnvFile(*flEnvFile)
+	if err != nil {
+		return nil, nil, cmd, err
+	}
+	envVariables = append(envVariables, parsedVars...)
+	// boo, there's no debug output for docker run
+	//utils.Debugf("Environment variables for the container: %#v", envVariables)
+
 	config := &Config{
 		Hostname:        hostname,
 		Domainname:      domainname,
@@ -213,7 +225,7 @@ func parseRun(cmd *flag.FlagSet, args []string, sysInfo *sysinfo.SysInfo) (*Conf
 		AttachStdin:     flAttach.Get("stdin"),
 		AttachStdout:    flAttach.Get("stdout"),
 		AttachStderr:    flAttach.Get("stderr"),
-		Env:             flEnv.GetAll(),
+		Env:             envVariables,
 		Cmd:             runCmd,
 		Dns:             flDns.GetAll(),
 		DnsSearch:       flDnsSearch.GetAll(),