Merge pull request #45 from bnea-engineering/feature/overwrite_redis_…

…addr_with_env_variable

support REDIS_ADDR environment variable

README.md

@@ -60,6 +60,7 @@ These settings take precedence over any configurations provided by [environment
 
 Name               | Description
 -------------------|------------
+REDIS_ADDR         | Address of Redis node(s)
 REDIS_PASSWORD     | Password to use when authenticating to Redis
 
 ### What's exported?

main.go

@@ -13,8 +13,8 @@ import (
 )
 
 var (
-	redisAddr     = flag.String("redis.addr", "redis://localhost:6379", "Address of one or more redis nodes, separated by separator")
-	redisPassword = flag.String("redis.password", os.Getenv("REDIS_PASSWORD"), "Password for one or more redis nodes, separated by separator")
+	redisAddr     = flag.String("redis.addr", getEnv("REDIS_ADDR", "redis://localhost:6379"), "Address of one or more redis nodes, separated by separator")
+	redisPassword = flag.String("redis.password", getEnv("REDIS_PASSWORD", ""), "Password for one or more redis nodes, separated by separator")
 	namespace     = flag.String("namespace", "redis", "Namespace for metrics")
 	checkKeys     = flag.String("check-keys", "", "Comma separated list of keys to export value and length/size")
 	separator     = flag.String("separator", ",", "separator used to split redis.addr and redis.password into several elements.")
@@ -89,3 +89,12 @@ func main() {
 	log.Printf("Connecting to redis hosts: %#v", addrs)
 	log.Fatal(http.ListenAndServe(*listenAddress, nil))
 }
+
+// getEnv gets an environment variable from a given key and if it doesn't exist,
+// returns defaultVal given.
+func getEnv(key string, defaultVal string) string {
+	if envVal, ok := os.LookupEnv(key); ok {
+		return envVal
+	}
+	return defaultVal
+}