CODEWITHSUNDEEP
google-cloud-platformgoogle-cloud-functionsgoogle-cloud-pubsub
martosoler
martosoler

Reputation: 433

Can I use Google Cloud Pub/Sub across different Google Cloud projects?

Let's say I have project A, B and C in Google Cloud with several cloud functions in each one.

I want to setup a Pub/Sub in project C so the functions in A and B can subscribe to.

Is this possible? Do I need to setup some kind of service account with custom permissions?

Thanks

Upvotes: 17

Views: 25365

Answers (2)

Calle Engene
Calle Engene

Reputation: 886

In the subscribing project on the IAM page, add a new member with the Pub/Sub Publisher role, the new member name is the serviceaccount-email of from the publishing project. Then create a cloud function in the publishing project and assign the same service-account in the bottom of the page(under more) to the function.

Here's a node example for a cloud function:

const PubSub = require('@google-cloud/pubsub');
const pubsub = new PubSub();
const topic = pubsub.topic('projects/subscribing-project-name/topics/topic-to-publish-to');
const publisher = topic.publisher();

exports.helloWorld = (req, res) => {
    
    const customAttributes = {
        message: 'Hello'
    };
    
    publisher.publish(
        Buffer.from("Hello from another project"), customAttributes, 
        (err) => {
            if (err) {
                res.status(500).send(JSON.stringify({
                    success: false,
                    error: err.message 
                }));
                return;
            }
            res.status(200).send(JSON.stringify({
                success: true,
                message: "Message sent to pubsub topic" 
            }));
        }
    );
};

Upvotes: 13

komarkovich
komarkovich

Reputation: 2319

As you mentioned in the comment, you can subscribe to the topic from another Cloud Functions if you set a push subscription.

To publish to a Pub/Sub topic from another project you should grant the right permissions for it's service account in the destination project.

Upvotes: 5

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