Create triggers from Pub/Sub events

In Cloud Run, you can trigger services in response to Pub/Sub messages using Eventarc. When you specify a Pub/Sub trigger for your service, you also specify a Pub/Sub topic. As a result of this trigger, your service is called whenever you publish a message to the specified topic.

The Google Events repository contains additional resources for working with event data.

Before you begin

1. Make sure you have set up a new project for Cloud Run as described in the setup page.

2. Enable the Artifact Registry, Cloud Build, Cloud Run Admin API, Eventarc, Cloud Logging, and Pub/Sub APIs:

   Enable the APIs

Set required roles

You or your administrator must grant the deployer account, the trigger identity, and optionally, the Pub/Sub service agent the following IAM roles.

Required roles for the deployer account

To get the permissions that you need to trigger from Pub/Sub events, ask your administrator to grant you the following IAM roles on your project:

• Cloud Build Editor (roles/cloudbuild.builds.editor)
• Cloud Run Admin (roles/run.admin)
• Eventarc Admin (roles/eventarc.admin)
• Logs View Accessor (roles/logging.viewAccessor)
• Project IAM Admin (roles/resourcemanager.projectIamAdmin)
• Service Account Admin (roles/iam.serviceAccountAdmin)
• Service Account User (roles/iam.serviceAccountUser)
• Service Usage Admin (roles/serviceusage.serviceUsageAdmin)

For more information about granting roles, see Manage access to projects, folders, and organizations.

You might also be able to get the required permissions through custom roles or other predefined roles.

Note that by default, Cloud Build permissions include permissions to upload and download Artifact Registry artifacts.

Required roles for the trigger identity

1. Make note of the Compute Engine default service account as you will you attach it to an Eventarc trigger to represent the identity of the trigger for testing purposes. This service account is automatically created after enabling or using a Google Cloud service that uses Compute Engine, and with the following email format:

   [e-mail]

   Replace PROJECT_NUMBER with your Google Cloud project number. You can find your project number on the Welcome page of the Google Cloud console or by running the following command:

   gcloud projects describe PROJECT_ID --format='value(projectNumber)'

   For production environments, we strongly recommend creating a new service account and granting it one or more IAM roles that contain the minimum permissions required and follow the principle of least privilege.

   Note:

   The iam.automaticIamGrantsForDefaultServiceAccounts organization policy constraint prevents the Editor role from being automatically granted to default service accounts. If you created your organization after May 3, 2024, this constraint is enforced by default.

   We strongly recommend that you enforce this constraint to disable the automatic role grant. If you disable the automatic role grant, you must decide which roles to grant to the default service accounts, and then grant these roles yourself.

   If the default service account already has the Editor role, we recommend that you replace the Editor role with less permissive roles.To safely modify the service account's roles, use Policy Simulator to see the impact of the change, and then grant and revoke the appropriate roles.

2. By default, Cloud Run services are only callable by Project Owners, Project Editors, and Cloud Run Admins and Invokers. You can control access on a per-service basis; however, for testing purposes, grant the Cloud Run Invoker role (run.invoker) on the Google Cloud project to the Compute Engine service account. This grants the role on all Cloud Run services and jobs in a project.

   gcloud projects add-iam-policy-binding PROJECT_ID \
       --member=serviceAccount:[e-mail] \
       --role=roles/run.invoker

   Note that if you create a trigger for an authenticated Cloud Run service without granting the Cloud Run Invoker role, the trigger is created successfully and is active. However, the trigger will not work as expected and a message similar to the following appears in the logs:

   The request was not authenticated. Either allow unauthenticated invocations or set the proper Authorization header.
3. Grant the Eventarc Event Receiver role (roles/eventarc.eventReceiver) on the project to the Compute Engine default service account so that the Eventarc trigger can receive events from event providers.

   gcloud projects add-iam-policy-binding PROJECT_ID \
       --member=serviceAccount:[e-mail] \
       --role=roles/eventarc.eventReceiver

Optional role for the Pub/Sub service agent

• If you enabled the Cloud Pub/Sub service agent on or before April 8, 2021, to support authenticated Pub/Sub push requests, grant the Service Account Token Creator role (roles/iam.serviceAccountTokenCreator) to the service agent. Otherwise, this role is granted by default:

  gcloud projects add-iam-policy-binding PROJECT_ID \
      --member=serviceAccount:[e-mail] \
      --role=roles/iam.serviceAccountTokenCreator

Create a trigger for services

You can specify a trigger after you deploy a service.

Click the tab for instructions using the tool of your choice.

Console

1. Deploy your Cloud Run service using containers or from source.

2. In the Google Cloud console, go to Cloud Run:

   Go to Cloud Run

3. From the list of services, click an existing service.

4. On the Service details page, navigate to the Triggers tab.

5. Click Add trigger, and select Pub/Sub trigger.

6. In the Eventarc trigger pane, modify the trigger details as follows:

   1. In the Trigger name field, enter a name for the trigger, or use the default name.

   2. Select a Trigger type from the list to specify one of the following trigger types:

      • Google Sources to specify triggers for Pub/Sub, Cloud Storage, Firestore, and other Google event providers.

      • Third-party to integrate with non-Google providers that offer an Eventarc source. For more information, see Third-party events in Eventarc.

   3. Select Pub/Sub from the Event provider list, to select a product that provides the type of event for triggering your service. For the list of event providers, see Event providers and destinations.

   4. Select google.cloud.pubsub.topic.v1.messagePublished from the Event type list. Your trigger configuration varies depending on the supported event type. For more information, see Event types.

   5. From the Select a Cloud Pub/Sub topic topic field, choose a topic for the trigger to monitor. Messages you publish to this topic trigger calls to your function.

   6. If the Region field is enabled, select a location for the Eventarc trigger. In general, the location of an Eventarc trigger should match the location of the Google Cloud resource that you want to monitor for events. In most scenarios, you should also deploy your service in the same region. See Understand Eventarc locations for more details about Eventarc trigger locations.

   7. In the Service account field, select a service account. Eventarc triggers are linked to service accounts to use as an identity when invoking your service. Your Eventarc trigger's service account must have the permission to invoke your service. By default, Cloud Run uses the Compute Engine default service account.

   8. Optionally, specify the Service URL path to send the incoming request to. This is the relative path on the destination service to which the events for the trigger should be sent. For example: /, /route, route, and route/subroute.

   9. Once you've completed the required fields, click Save trigger.

7. After creating the trigger, verify its health by ensuring that there is a checkmark on the Triggers tab.

   Note: Although a trigger is created immediately, it can take up to two minutes for a trigger to propagate and filter events.

gcloud

1. Deploy your Cloud Run service using containers or from source.

2. Run the following command to create a trigger that filters events:

   gcloud eventarc triggers create TRIGGER_NAME  \
       --location=EVENTARC_TRIGGER_LOCATION \
       --destination-run-service=SERVICE  \
       --destination-run-region=REGION \
       --event-filters="type=google.cloud.pubsub.topic.v1.messagePublished" \
       --transport-topic=projects/PROJECT_ID/topics/TOPIC_ID \
       --service-account=[e-mail]
   

   Replace:

   • TRIGGER_NAME with the name for your trigger.

   • EVENTARC_TRIGGER_LOCATION with the location for the Eventarc trigger. In general, the location of an Eventarc trigger should match the location of the Google Cloud resource that you want to monitor for events. In most scenarios, you should also deploy your service in the same region. For more information, see Eventarc locations.

   • SERVICE with the name of the service you are deploying.

   • REGION with the Cloud Run region of the service. For example, europe-west1.

   • PROJECT_NUMBER with your Google Cloud project number. Eventarc triggers are linked to service accounts to use as an identity when invoking your service. Your Eventarc trigger's service account must have the permission to invoke your service. By default, Cloud Run uses the Default compute service account.

   Each event-filters flag specifies a type of event, with the function triggering only when an event meets all of the criteria specified in its event-filters flags. Each trigger must have an event-filters flag specifying a supported event type, such as a new document written to Firestore or a file uploaded to Cloud Storage. You can't change the event filter type after creation. To change the event filter type, you must create a new trigger and delete the old one. Optionally, you can repeat the --event-filters flag with a supported filter in the form ATTRIBUTE=VALUE to add more filters.

Terraform

To create an Eventarc trigger for a Cloud Run service, see Create a trigger using Terraform.

Create a trigger for functions

Click the tab for instructions using the tool of your choice.

Console

When you use the Google Cloud console to create a function, you can also add a trigger to your function. Follow these steps to create a trigger for your function:

1. In the Google Cloud console, go to Cloud Run:

   Go to Cloud Run

2. Click Write a function, and enter the function details. For more information about configuring functions during deployment, see Deploy functions.

3. In the Trigger section, click Add trigger.

4. Select Pub/Sub trigger.

5. In the Eventarc trigger pane, modify the trigger details as follows:

   1. Enter a name for the trigger in the Trigger name field, or use the default name.

   2. Select a Trigger type from the list:

      • Google Sources to specify triggers for Pub/Sub, Cloud Storage, Firestore, and other Google event providers.

      • Third-party to integrate with non-Google providers that offer an Eventarc source. For more information, see Third-party events in Eventarc.

   3. Select Pub/Sub from the Event provider list, to select a product that provides the type of event for triggering your function. For the list of event providers, see Event providers and destinations.

   4. Select google.cloud.pubsub.topic.v1.messagePublished from the Event type list. Your trigger configuration varies depending on the supported event type. For more information, see Event types.

   5. From the Select a Cloud Pub/Sub topic topic field, choose a topic for the trigger to monitor. Messages you publish to this topic trigger calls to your function.

   6. If the Region field is enabled, select a location for the Eventarc trigger. In general, the location of an Eventarc trigger should match the location of the Google Cloud resource that you want to monitor for events. In most scenarios, you should also deploy your function in the same region. See Understand Eventarc locations for more details about Eventarc trigger locations.

   7. In the Service account field, select a service account. Eventarc triggers are linked to service accounts to use as an identity when invoking your function. Your Eventarc trigger's service account must have the permission to invoke your function. By default, Cloud Run uses the Compute Engine default service account.

   8. Optionally, specify the Service URL path to send the incoming request to. This is the relative path on the destination service to which the events for the trigger should be sent. For example: /, /route, route, and route/subroute.

6. Once you've completed the required fields, click Save trigger.

gcloud

When you create a function using the gcloud CLI, you must first deploy your function, and then create a trigger. Follow these steps to create a trigger for your function:

1. Run the following command in the directory that contains the sample code to deploy your function:

   gcloud run deploy FUNCTION \
           --source . \
           --function FUNCTION_ENTRYPOINT \
           --base-image BASE_IMAGE_ID \
           --region REGION
   

   Replace:

   • FUNCTION with the name of the function you are deploying. You can omit this parameter entirely, but you will be prompted for the name if you omit it.

   • FUNCTION_ENTRYPOINT with the entry point to your function in your source code. This is the code Cloud Run executes when your function runs. The value of this flag must be a function name or fully-qualified class name that exists in your source code.

   • BASE_IMAGE_ID with the base image environment for your function. For more details about base images and the packages included in each image, see Runtimes base images.

   • REGION with the Google Cloud region where you want to deploy your function. For example, europe-west1.

2. Run the following command to create a trigger that filters events:

   gcloud eventarc triggers create TRIGGER_NAME  \
       --location=EVENTARC_TRIGGER_LOCATION \
       --destination-run-service=FUNCTION  \
       --destination-run-region=REGION \
       --event-filters="type=google.cloud.pubsub.topic.v1.messagePublished" \
       --transport-topic=projects/PROJECT_ID/topics/TOPIC_ID \
       --service-account=[e-mail]
   

   Replace:

   • TRIGGER_NAME with the name for your trigger.

   • EVENTARC_TRIGGER_LOCATION with the location for the Eventarc trigger. In general, the location of an Eventarc trigger should match the location of the Google Cloud resource that you want to monitor for events. In most scenarios, you should also deploy your function in the same region. For more information, see Eventarc locations.

   • FUNCTION with the name of the function you are deploying.

   • REGION with the Cloud Run region of the function.

   • PROJECT_NUMBER with your Google Cloud project number. Eventarc triggers are linked to service accounts to use as an identity when invoking your function. Your Eventarc trigger's service account must have the permission to invoke your function. By default, Cloud Run uses the Default compute service account.

   Each event-filters flag specifies a type of event, with the function triggering only when an event meets all of the criteria specified in its event-filters flags. Each trigger must have an event-filters flag specifying a supported event type, such as a new document written to Firestore or a file uploaded to Cloud Storage. You can't change the event filter type after creation. To change the event filter type, you must create a new trigger and delete the old one. Optionally, you can repeat the --event-filters flag with a supported filter in the form ATTRIBUTE=VALUE to add more filters.

Terraform

To create an Eventarc trigger for a Cloud Run function, see Create a trigger using Terraform.

Next steps

• Learn how to trigger with events.
• Learn how to trigger services from Pub/Sub.