Using JWT AccessTokens with Google Cloud Client Libraries

project='your-project-id'

from google.auth import jwt
from google.cloud import pubsub_v1

audience = 'https://pubsub.googleapis.com/google.pubsub.v1.Publisher'
credentials = jwt.Credentials.from_service_account_file(
    '/path/to/svc_account.json',
    audience=audience)

publisher = pubsub_v1.PublisherClient(credentials=credentials)
project_path = f"projects/{project}"
for topic in publisher.list_topics(request={"project": project_path}):
  print(topic.name)

package main

import (
	"fmt"
	"io/ioutil"

	pubsub "cloud.google.com/go/pubsub"
	"golang.org/x/net/context"
	"golang.org/x/oauth2/google"
	"google.golang.org/api/iterator"
	"google.golang.org/api/option"
)

const (
	projectID = "your-project-id"
)

func main() {

	ctx := context.Background()

	keyBytes, err := ioutil.ReadFile("/path/to/svc_account.json")
	if err != nil {
		panic(err)
	}

	aud := "https://pubsub.googleapis.com/google.pubsub.v1.Publisher"
	tokenSource, err := google.JWTAccessTokenSourceFromJSON(keyBytes, aud)
	if err != nil {
		panic(err)
	}

	//creds, err := google.JWTAccessTokenSourceWithScope()
	pubsubClient, err := pubsub.NewClient(ctx, projectID, option.WithTokenSource(tokenSource))
	if err != nil {
		fmt.Printf("pubsub.NewClient: %v", err)
		return
	}
	defer pubsubClient.Close()

	pit := pubsubClient.Topics(ctx)
	for {
		topic, err := pit.Next()
		if err == iterator.Done {
			break
		}
		if err != nil {
			fmt.Printf("pubssub.Iterating error: %v", err)
			return
		}
		fmt.Printf("Topic Name: %s\n", topic.ID())
	}
}

package com.test;

import com.google.cloud.pubsub.v1.TopicAdminClient;
import com.google.cloud.pubsub.v1.TopicAdminClient.ListTopicsPagedResponse;
import com.google.cloud.pubsub.v1.TopicAdminSettings;

import com.google.pubsub.v1.ListTopicsRequest;
import com.google.pubsub.v1.ProjectName;
import com.google.pubsub.v1.Topic;
import com.google.api.gax.core.FixedCredentialsProvider;
import com.google.auth.oauth2.ServiceAccountJwtAccessCredentials;
import java.io.File;
import java.io.InputStream;
import java.net.URI;
import java.io.FileInputStream;

public class TestApp {
	public static void main(String[] args) {
		TestApp tc = new TestApp();
	}

	public TestApp() {
		try {

			String serviceAccuntKey = "/path/to/svc_account.json";

			URI audience = new URI("https://pubsub.googleapis.com/google.pubsub.v1.Publisher");

			InputStream credentialsStream = new FileInputStream(new File(serviceAccuntKey));
			ServiceAccountJwtAccessCredentials credentials = ServiceAccountJwtAccessCredentials
					.fromStream(credentialsStream, audience);
			TopicAdminClient topicClient = TopicAdminClient
					.create(TopicAdminSettings.newBuilder()
							.setCredentialsProvider(FixedCredentialsProvider.create(credentials)).build());

			ListTopicsRequest listTopicsRequest = ListTopicsRequest.newBuilder()
					.setProject(ProjectName.format("your-project-id"))
					.build();

			ListTopicsPagedResponse response = topicClient.listTopics(listTopicsRequest);
			Iterable<Topic> topics = response.iterateAll();
			for (Topic topic : topics)
				System.out.println(topic);

		} catch (Exception ex) {
			System.out.println("Error: " + ex);
		}
	}

}

var log4js = require("log4js");
var logger = log4js.getLogger();

const {GoogleAuth, JWTAccess, OAuth2Client} =  require('google-auth-library');
const {PubSub} = require('@google-cloud/pubsub');

key = require("/path/to/svc_account.json");
const projectId = 'your-project-id';
const aud = "https://pubsub.googleapis.com/google.pubsub.v1.Publisher";
const client = new JWTAccess();
client.fromJSON(key);

const md = client.getRequestHeaders(aud);

console.log(md);

// TODO, attach the client to pubsub somehow

// https://cloud.google.com/nodejs/docs/reference/pubsub/latest/pubsub/clientconfig
// const pubsub = new PubSub({
//   projectId: projectId,
// });
// pubsub.getTopics((err, topic) => {
// 	if (err) {
// 		console.log(err);
// 		return;
// 	}
// 	topic.forEach(function(entry) {
//     logger.info(entry.name);
// 	});
// });

using System;

using Google.Cloud.PubSub.V1;
using System.Threading.Tasks;
using System.IO;
using Google.Api.Gax.ResourceNames;
using Google.Api.Gax.Grpc;
using Google.Apis;
using Google.Apis.Auth.OAuth2;
using Grpc.Auth;

namespace main
{
    class Program
    {
        const string projectID = "your-project-id";
        [STAThread]
        static void Main(string[] args)
        {
            new Program().Run().Wait();
        }

        private Task Run()
        {
            var _audience = "https://pubsub.googleapis.com/google.pubsub.v1.Publisher";
            var keyFile = "/path/to/svc_account.json";
            var stream = new FileStream(keyFile, FileMode.Open, FileAccess.Read);
            ServiceAccountCredential cred = ServiceAccountCredential.FromServiceAccountData(stream);
            var token = cred.GetAccessTokenForRequestAsync(_audience).Result;
            Console.WriteLine(token);

            // i don't know how to attach the credential to the client here...
            
            PublisherServiceApiClient publisher = PublisherServiceApiClient.Create();
            ProjectName projectName = ProjectName.FromProject(projectID);

            foreach (Topic t in publisher.ListTopics(projectName))
                Console.WriteLine(t.MessageStoragePolicy);
            return Task.CompletedTask;
        }
    }
}