Fix #15: Add basic support for expvar

README.md

@@ -44,6 +44,8 @@ $ ./TrendingGithub -help
 Usage of ./TrendingGithub:
   -debug
     	Outputs the tweet instead of tweet it (useful for development). Env var: TRENDINGGITHUB_DEBUG
+  -expvar-port int
+    	Port which will be used for the expvar TCP server. Env var: TRENDINGGITHUB_EXPVAR_PORT (default 8123)
   -storage-auth string
     	Storage Auth (e.g. myPassword or <empty>). Env var: TRENDINGGITHUB_STORAGE_AUTH
   -storage-url string
@@ -53,7 +55,7 @@ Usage of ./TrendingGithub:
   -twitter-access-token-secret string
     	Twitter-API: Access token secret. Env var: TRENDINGGITHUB_TWITTER_ACCESS_TOKEN_SECRET
   -twitter-conf-refresh-time duration
-    	Twitter: Time interval to refresh the configuration of twitter (e.g. char length for short url). Default: 24h. Env var: TRENDINGGITHUB_TWITTER_CONF_REFRESH_TIME (default 24h0m0s)
+    	Twitter: Time interval to refresh the configuration of twitter (e.g. char length for short url). Env var: TRENDINGGITHUB_TWITTER_CONF_REFRESH_TIME (default 24h0m0s)
   -twitter-consumer-key string
     	Twitter-API: Consumer key. Env var: TRENDINGGITHUB_TWITTER_CONSUMER_KEY
   -twitter-consumer-secret string

expvar.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	_ "expvar"
+	"fmt"
+	"log"
+	"net"
+	"net/http"
+)
+
+// StartExpvarServer will start a small tcp server for the expvar package.
+// This server is only available via localhost on localhost:port/debug/vars
+func StartExpvarServer(port int) error {
+	sock, err := net.Listen("tcp", fmt.Sprintf("localhost:%d", port))
+	if err != nil {
+		return err
+	}
+
+	go func() {
+		log.Printf("Expvar initialisation success: HTTP now available at http://localhost:%d/debug/vars", port)
+		http.Serve(sock, nil)
+	}()
+
+	return nil
+}

flags/flags.go

@@ -34,6 +34,21 @@ func String(name, env, fallback, help string) *string {
 	return flag.String(name, value, help)
 }
 
+// Int registers a flag and returns the pointer to the resulting int.
+// The default value is passed as fallback and env sets the env variable
+// that can override the default.
+func Int(name, env string, fallback int, help string) *int {
+	value := fallback
+	if v := os.Getenv(env); v != "" {
+		if i, err := strconv.Atoi(v); err == nil {
+			value = i
+		}
+
+	}
+
+	return flag.Int(name, value, help)
+}
+
 // Duration registers a flag and returns the pointer to the resulting duration.
 // The default value is passed as fallback and env sets the env variable
 // that can override the default.

main.go

@@ -34,6 +34,7 @@ func main() {
 		storageURL  = flags.String("storage-url", "TRENDINGGITHUB_STORAGE_URL", ":6379", "Storage URL (e.g. 1.2.3.4:6379 or :6379). Env var: TRENDINGGITHUB_STORAGE_URL")
 		storageAuth = flags.String("storage-auth", "TRENDINGGITHUB_STORAGE_AUTH", "", "Storage Auth (e.g. myPassword or <empty>). Env var: TRENDINGGITHUB_STORAGE_AUTH")
 
+		expVarPort  = flags.Int("expvar-port", "TRENDINGGITHUB_EXPVAR_PORT", 8123, "Port which will be used for the expvar TCP server. Env var: TRENDINGGITHUB_EXPVAR_PORT")
 		showVersion = flags.Bool("version", "TRENDINGGITHUB_VERSION", false, "Outputs the version number and exit. Env var: TRENDINGGITHUB_VERSION")
 		debugMode   = flags.Bool("debug", "TRENDINGGITHUB_DEBUG", false, "Outputs the tweet instead of tweet it (useful for development). Env var: TRENDINGGITHUB_DEBUG")
 	)
@@ -59,10 +60,9 @@ func main() {
 			log.Fatalf("Twitter Configuration initialisation failed: %s", err)
 		}
 		log.Printf("Twitter Configuration initialisation success: ShortUrlLength %d\n", twitterClient.Configuration.ShortUrlLength)
+		twitterClient.SetupConfigurationRefresh(*configurationRefreshTime)
 	}
 
-	twitterClient.SetupConfigurationRefresh(*configurationRefreshTime)
-
 	// Activate our growth hack feature
 	// Checkout the README for details or read the code (suggested).
 	if *twitterFollowNewPerson {
@@ -75,6 +75,13 @@ func main() {
 	defer storageBackend.Close()
 	log.Println("Storage backend initialisation success")
 
+	// Start the exvar server
+	err := StartExpvarServer(*expVarPort)
+	if err != nil {
+		log.Fatalf("Expvar initialisation failed: %s", err)
+	}
+	log.Println("Expvar initialisation started ...")
+
 	// Let the party begin
 	StartTweeting(twitterClient, storageBackend, *tweetTime)
 }