cmd/golangorg: fall back to embedded content when _content is not nearby

If golangbuild is run from a directory other than x/website root or its
cmd/golangbuild directory, it's more useful to use the embedded content
than a directory that does not exist.

This was previously possible by explicitly setting the -content flag to
the empty string. This change makes it possible to leave the flag unset,
which can be handy for go run golang.org/x/website/cmd/golangorg@latest.

Change-Id: Id0e33515b15934fdfcd1cbe594ad4c7b969a1d21
Reviewed-on: https://go-review.googlesource.com/c/website/+/589936
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

1 files changed, 20 insertions, 5 deletions

diff --git a/cmd/golangorg/server.go b/cmd/golangorg/server.go
index 6c42ade3..d0191b65 100644
--- a/cmd/golangorg/server.go
+++ b/cmd/golangorg/server.go
@@ -74,16 +74,18 @@ func usage() {
 }
 
 func main() {
-	// Running locally, find the local _content directory,
+	// Running locally, find the local _content directory when it's available nearby,
 	// so that updates to those files appear on the local dev instance without restarting.
 	// On App Engine, leave contentDir empty, so we use the embedded copy,
 	// which is much faster to access than the simulated file system.
 	if *contentDir == "" && !runningOnAppEngine {
-		repoRoot := "../.."
-		if _, err := os.Stat("_content"); err == nil {
-			repoRoot = "."
+		if fi, err := os.Stat(filepath.Join("..", "..", "_content")); err == nil && fi.IsDir() {
+			*contentDir = fi.Name()
+		} else if fi, err := os.Stat("_content"); err == nil && fi.IsDir() {
+			*contentDir = fi.Name()
+		} else {
+			*contentDir = "" // Fall back to using embedded content.
 		}
-		*contentDir = filepath.Join(repoRoot, "_content")
 	}
 
 	if runningOnAppEngine {
@@ -119,6 +121,7 @@ func main() {
 		log.Printf("\tversion = %s", runtime.Version())
 		log.Printf("\taddress = %s", *httpAddr)
 		log.Printf("\tgoroot = %s", *goroot)
+		log.Printf("\tcontent = %s", contentSource())
 		handler = loggingHandler(handler)
 	}
 
@@ -129,6 +132,18 @@ func main() {
 	}
 }
 
+// contentSource returns a human-readable description
+// of where the x/website _content dir is coming from.
+func contentSource() string {
+	if *contentDir == "" {
+		return "embedded content"
+	} else if abs, err := filepath.Abs(*contentDir); err == nil {
+		return abs
+	} else {
+		return *contentDir
+	}
+}
+
 //go:embed testdata
 var testdataFS embed.FS