feat: Add support for custom config file path

README.md

@@ -54,6 +54,8 @@ You are now ready to send alerts to Google Chat!
 
 -   Alertmanager has the ability of group similar alerts together and fire only one event, clubbing all the alerts data into one event. `calert` leverages this and sends all alerts in one message by looping over the alerts and passing data in the template. You can configure the rules for grouping the alerts in `alertmanager.yml` config. You can read more about it [here](https://github.com/prometheus/docs/blob/master/content/docs/alerting/alertmanager.md#grouping)
 
+-   You can use `--config.file` parameter to supply a custom config file path while running `calert`.
+
 ## API
 
 -   POST `/create?room_name=<>` (Used to receive new alerts and push to Google Chat)

main.go

@@ -60,21 +60,30 @@ func initConfig() {
 		os.Exit(0)
 	}
 
-	viper.SetConfigName("config")
+	// Config Path flag.
+	flagSet.String("config.file", "", "Path to config file")
+
 	viper.SetDefault("server.address", ":5000")
 	viper.SetDefault("server.socket", "/tmp/calert.sock")
 	viper.SetDefault("server.name", "calert")
 	viper.SetDefault("server.read_timeout", 1000)
 	viper.SetDefault("server.write_timeout", 5000)
 	viper.SetDefault("server.keepalive_timeout", 30000)
 	viper.SetDefault("server.max_body_size", 5000)
-
 	// Process flags.
 	flagSet.Parse(os.Args[1:])
 	viper.BindPFlags(flagSet)
 
 	// Config file.
-	viper.AddConfigPath(".")
+	// check if config.file flag is passed and read from the file if it is set
+	configPath := viper.GetString("config.file")
+	if configPath != "" {
+		viper.SetConfigFile(configPath)
+	} else {
+		// fallback to default config.
+		viper.SetConfigName("config")
+		viper.AddConfigPath(".")
+	}
 	err := viper.ReadInConfig()
 	if err != nil {
 		errLog.Fatalf("Error reading config: %s", err)