cmd/golangorg: serve tip.golang.org directly from Gerrit

This CL enables the code, committed in an earlier CL,
that serves tip.golang.org from an in-memory copy of the
Go repo, updated by a background loop, which will let us
retire the more heavyweight "deploy a whole new app in a loop"
that we currently use for tip.golang.org.

When this CL is committed, the "deploy a whole new app in a loop"
logic will deploy this new code, which will then start using the
in-memory copy, even though it is also being updated on each
change. At that point it will be safe to take down the app-updating
loop entirely, letting the default app do the serving.

Change-Id: Ica5cffd684c45d4a5b059772700a0a608f832bad
Reviewed-on: https://go-review.googlesource.com/c/website/+/335049
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Website-Publish: Russ Cox <rsc@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>

cmd/golangorg/server.go

@@ -113,6 +113,8 @@ func main() {
 	}
 }
 
+var isTestBinary = false
+
 // NewHandler returns the http.Handler for the web site,
 // given the directory where the content can be found
 // (can be "", in which case an internal copy is used)
@@ -144,12 +146,6 @@ func NewHandler(contentDir, goroot string) http.Handler {
 		log.Fatalf("newSite: %v", err)
 	}
 
-	// When we are ready to start serving tip.golang.org
-	// from the default golang-org app instead of a separate app,
-	// we can set serveTip = true.
-	const serveTip = false
-
-	if serveTip {
 	// tip.golang.org serves content from the very latest Git commit
 	// of the main Go repo, instead of the one the app is bundled with.
 	var tipGoroot atomicFS
@@ -163,6 +159,7 @@ func NewHandler(contentDir, goroot string) http.Handler {
 		log.Fatalf("loading beta site: %v", err)
 	}
 
+	if !isTestBinary {
 		go watchTip(&tipGoroot)
 	}
 

cmd/golangorg/server_test.go

@@ -12,6 +12,10 @@ import (
 	"golang.org/x/website/internal/webtest"
 )
 
+func init() {
+	isTestBinary = true
+}
+
 func TestWeb(t *testing.T) {
 	h := NewHandler("../../_content", runtime.GOROOT())
 	files, err := filepath.Glob("testdata/*.txt")