viper_firestore_configs.go

func ReadFirestoreConfigs() {
	ctx := context.Background()
	// we will use a service account to authenticate and authorize our app
	clientOptions := option.WithCredentialsFile("path/to/serviceAccountKey.json")
	app, err := firebase.NewApp(ctx, nil, clientOptions)
	if err != nil {
		log.Fatalln(err)
	}
	client, err := app.Firestore(ctx)
	if err != nil {
		log.Fatalln(err)
	}
	defer client.Close()
	// get latest config
	doc, err := client.Collection("configs").Doc("config").Get(ctx)
	if err != nil {
		log.Fatalln(err)
	}
	data := doc.Data()
	jsonData, err := json.Marshal(data)
	if err != nil {
		log.Fatalln(err)
	}
	err = viper.ReadConfig(bytes.NewBuffer(jsonData))
	if err != nil {
		log.Fatalln(err)
	}
	// listen for changes
	streamChanges := client.Doc("configs/config").Snapshots(ctx)
	defer streamChanges.Stop()
	for {
		snap, err := streamChanges.Next()
		if err != nil {
			log.Fatalln(err)
		}
		jsonData, err := json.Marshal(snap.Data())
		if err != nil {
			log.Fatalln(err)
		}
		viper.ReadConfig(bytes.NewBuffer(jsonData))
	}
}