Use env vars when config.yaml not exist

Signed-off-by: Asai Neko <sugar@sne.moe>

config/config.go

@@ -26,11 +26,15 @@ func Init() {
 	viper.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
 	viper.AutomaticEnv()
 
-	conf := &config{}
 	if err := viper.ReadInConfig(); err != nil {
-		// Dont generate config when using dev mode
-		log.Fatalln("[Config] Can't read config!")
+		if _, ok := err.(viper.ConfigFileNotFoundError); ok {
+			log.Println("[Config] No config file found, using Env vars only.")
+		} else {
+			log.Fatalf("[Config] Fatal error reading config file: %s \n", err)
+		}
 	}
+
+	conf := &config{}
 	if err := viper.Unmarshal(conf); err != nil {
 		log.Fatalln("[Condig] Can't unmarshal config!")
 	}