Trigger functions from Pub/Sub using Eventarc

This tutorial demonstrates how to write and trigger an event-driven Cloud Run functions with a Pub/Sub trigger.

You can configure the routing of events, including the event source and the event target, by specifying filters for an Eventarc trigger. For the example in this tutorial, publishing a message to a Pub/Sub topic triggers the event, and a request is sent to your function in the form of an HTTP request.

If you are new to Pub/Sub and want to learn more, see the Pub/Sub documentation for quickstarts and key references.

Objectives

In this tutorial, you will:

  1. Deploy an event-driven function.
  2. Create an Eventarc trigger.
  3. Trigger the function by publishing a message to a Pub/Sub topic.

Costs

In this document, you use the following billable components of Google Cloud:

To generate a cost estimate based on your projected usage, use the pricing calculator.

New Google Cloud users might be eligible for a free trial.

Before you begin

Security constraints defined by your organization might prevent you from completing the following steps. For troubleshooting information, see Develop applications in a constrained Google Cloud environment.

  1. Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.

  2. Install the Google Cloud CLI.

  3. If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

  4. To initialize the gcloud CLI, run the following command: 

    gcloud init

  5. Create or select a Google Cloud project.

    Roles required to select or create a project

    • Select a project: Selecting a project doesn't require a specific IAM role—you can select any project that you've been granted a role on.
    • Create a project: To create a project, you need the Project Creator (roles/resourcemanager.projectCreator), which contains the resourcemanager.projects.create permission. Learn how to grant roles.

    • Create a Google Cloud project:

      gcloud projects create PROJECT_ID

      Replace PROJECT_ID with a name for the Google Cloud project you are creating.

    • Select the Google Cloud project that you created:

      gcloud config set project PROJECT_ID

      Replace PROJECT_ID with your Google Cloud project name.

  6. Verify that billing is enabled for your Google Cloud project.

  7. Install the Google Cloud CLI.

  8. If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

  9. To initialize the gcloud CLI, run the following command: 

    gcloud init

  10. Create or select a Google Cloud project.

    Roles required to select or create a project

    • Select a project: Selecting a project doesn't require a specific IAM role—you can select any project that you've been granted a role on.
    • Create a project: To create a project, you need the Project Creator (roles/resourcemanager.projectCreator), which contains the resourcemanager.projects.create permission. Learn how to grant roles.

    • Create a Google Cloud project:

      gcloud projects create PROJECT_ID

      Replace PROJECT_ID with a name for the Google Cloud project you are creating.

    • Select the Google Cloud project that you created:

      gcloud config set project PROJECT_ID

      Replace PROJECT_ID with your Google Cloud project name.