Google Pub/Sub Subscriber sample in Golang

main.go

package main

import (
	"context"
	"fmt"
	"io/ioutil"
	"log"

	"golang.org/x/oauth2/google"

	"google.golang.org/api/option"

	"cloud.google.com/go/pubsub"
)

const (
	credentialJSONPath = ""
	projectID          = ""
	topicName          = ""
)

func main() {
	jsonKey, err := ioutil.ReadFile(credentialJSONPath)
	conf, err := google.JWTConfigFromJSON(jsonKey, pubsub.ScopePubSub, pubsub.ScopeCloudPlatform)
	if err != nil {
		log.Fatal(err)
	}
	ctx := context.Background()
	ts := conf.TokenSource(ctx)
	c, err := pubsub.NewClient(ctx, projectID, option.WithTokenSource(ts))
	if err != nil {
		log.Fatal("new client:", err)
	}

	sub := c.Subscription(topicName)
	err = sub.Receive(context.Background(), func(ctx context.Context, m *pubsub.Message) {
		log.Printf("Got message: %s", m.Data)
		m.Ack()
	})
	if err != nil {
		log.Fatal("Receive:", err)
	}
}