This recipe shows you how to publish messages to a Cloud Pub/Sub topic from a Cloud Function.

View the source code.

1. Follow the Cloud Functions quickstart guide to setup Cloud Functions for your project.

2. Clone this repository:

    git clone https://github.com/GoogleCloudPlatform/nodejs-docs-samples.git
    cd nodejs-docs-samples/functions/pubsub
   

3. Create a Cloud Pub/Sub topic (if you already have one you want to use, you can skip this step):

    gcloud beta pubsub topics create YOUR_TOPIC_NAME
   

   • Replace YOUR_TOPIC_NAME with the name of your Pub/Sub Topic.

4. Deploy the publish function with an HTTP trigger:

    cd publish/
    gcloud functions deploy publish --trigger-http --runtime YOUR_RUNTIME
   

   • Replace YOUR_RUNTIME with the name of the runtime you are using. For a complete list, see the gcloud reference.

5. Deploy the subscribe function with the Pub/Sub topic as a trigger:

    cd subscribe/
    gcloud functions deploy subscribe --trigger-topic YOUR_TOPIC_NAME --runtime YOUR_RUNTIME
   

   • Replace YOUR_TOPIC_NAME with the name of your Pub/Sub Topic.

6. Call the publish function:

    gcloud functions call publish --data '{"topic":"YOUR_TOPIC_NAME","message":"Hello World!"}'
   

   • Replace YOUR_TOPIC_NAME with the name of your Pub/Sub Topic.

7. Check the logs for the subscribe function:

    gcloud functions logs read subscribe
   

   You should see something like this in your console:

    D      ... User function triggered, starting execution
    I      ... Hello World!
    D      ... Execution took 1 ms, user function completed successfully