Move expvar under the registry section

For consistency with other systems, the redis and caching monitoring data has
been moved under the "registry" section in expvar. This ensures the entire
registry state is kept to a single section.

Signed-off-by: Stephen J Day <stephen.day@docker.com>

registry/handlers/app.go

@@ -272,13 +272,18 @@ func (app *App) configureRedis(configuration *configuration.Configuration) {
 
 	app.redis = pool
 
-	expvar.Publish("redis", expvar.Func(func() interface{} {
+	// setup expvar
+	registry := expvar.Get("registry")
+	if registry == nil {
+		registry = expvar.NewMap("registry")
+	}
+
+	registry.(*expvar.Map).Set("redis", expvar.Func(func() interface{} {
 		return map[string]interface{}{
 			"Config": configuration.Redis,
 			"Active": app.redis.ActiveCount(),
 		}
 	}))
-
 }
 
 func (app *App) ServeHTTP(w http.ResponseWriter, r *http.Request) {

registry/storage/layercache.go

@@ -174,7 +174,26 @@ var layerInfoCacheMetrics struct {
 }
 
 func init() {
-	expvar.Publish("layerinfocache", expvar.Func(func() interface{} {
+	registry := expvar.Get("registry")
+	if registry == nil {
+		registry = expvar.NewMap("registry")
+	}
+
+	cache := registry.(*expvar.Map).Get("cache")
+	if cache == nil {
+		cache = &expvar.Map{}
+		cache.(*expvar.Map).Init()
+		registry.(*expvar.Map).Set("cache", cache)
+	}
+
+	storage := cache.(*expvar.Map).Get("storage")
+	if storage == nil {
+		storage = &expvar.Map{}
+		storage.(*expvar.Map).Init()
+		cache.(*expvar.Map).Set("storage", storage)
+	}
+
+	storage.(*expvar.Map).Set("layerinfo", expvar.Func(func() interface{} {
 		// no need for synchronous access: the increments are atomic and
 		// during reading, we don't care if the data is up to date. The
 		// numbers will always *eventually* be reported correctly.