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

3. Grant the required IAM roles and permissions.

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.

Create a trigger for services

After deploying a service, you can configure a trigger using the Google Cloud console, Google Cloud CLI, or Terraform.

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. Optionally, to enable retries if the delivery attempt fails, select the Enable retry on failure checkbox; otherwise, the default behavior is a single delivery attempt with no retries. For more information, see Retry events.

   10. 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 and routes events:

   gcloud eventarc triggers create TRIGGER_NAME  \
       --location=LOCATION \
       --destination-run-service=DESTINATION_RUN_SERVICE  \
       --destination-run-region=DESTINATION_RUN_REGION \
       --event-filters="type=google.cloud.pubsub.topic.v1.messagePublished" \
       --transport-topic=projects/PROJECT_ID/topics/TOPIC_ID \
       --service-account=SERVICE_ACCOUNT_NAME@PROJECT_ID.iam.gserviceaccount.com
   

   Replace the following:

   • TRIGGER_NAME: the ID of the trigger or a fully qualified identifier.
   • LOCATION: the location of the Eventarc trigger. Alternatively, you can set the eventarc/location property; for example, gcloud config set eventarc/location us-central1.

     To avoid any performance and data residency issues, the location must match the location of the Google Cloud service that is generating events. For more information, see Eventarc locations.

   • DESTINATION_RUN_SERVICE: the name of the Cloud Run service that receives the events for the trigger. The service can be in any of the Cloud Run supported locations and doesn't need to be in the same location as the trigger. However, the service must be in the same project as the trigger and will receive events as HTTP POST requests sent to its root URL path (/), whenever the event is generated.
   • DESTINATION_RUN_REGION: (optional) the Cloud Run location in which the destination Cloud Run service can be found. If not specified, it is assumed that the service is in the same region as the trigger.
   • The --event-filters="type=google.cloud.pubsub.topic.v1.messagePublished" flag is required and can't be changed. For a different event type, you must create a new trigger.
   • TOPIC_ID: the ID of the existing Pub/Sub topic. The topic must be in the same project as the trigger.
   • SERVICE_ACCOUNT_NAME: the name of your user-managed service account.
   • PROJECT_ID: your Google Cloud project ID.

   Notes:

   • Optionally, to specify a single event delivery attempt with no retries, use the --max-retry-attempts flag. The only valid value is 1. If you omit the flag, the standard retry behavior applies. For more information, see Retry events.
   • Other flags are available. For more information, see gcloud eventarc triggers create.

Terraform

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

Create a trigger for functions

After deploying a function, you can configure a trigger using the Google Cloud console, Google Cloud CLI, or Terraform.

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.

   9. Optionally, to enable retries if the delivery attempt fails, select the Enable retry on failure checkbox; otherwise, the default behavior is a single delivery attempt with no retries. For more information, see Retry events.

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

7. Click Create.

8. In the Source tab, edit the source code if needed, then select Save and redeploy.

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 the following:

   • FUNCTION: 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: 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: 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: 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 and routes events:

   gcloud eventarc triggers create TRIGGER_NAME  \
       --location=LOCATION \
       --destination-run-service=FUNCTION  \
       --destination-run-region=DESTINATION_RUN_REGION \
       --event-filters="type=google.cloud.pubsub.topic.v1.messagePublished" \
       --transport-topic=projects/PROJECT_ID/topics/TOPIC_ID \
       --service-account=SERVICE_ACCOUNT_NAME@PROJECT_ID.iam.gserviceaccount.com
   

   Replace the following:

   • TRIGGER_NAME: the ID of the trigger or a fully qualified identifier.
   • LOCATION: the location of the Eventarc trigger. Alternatively, you can set the eventarc/location property; for example, gcloud config set eventarc/location us-central1.

     To avoid any performance and data residency issues, the location must match the location of the Google Cloud service that is generating events. For more information, see Eventarc locations.

   • FUNCTION: the name of the deployed Cloud Run function that receives the events for the trigger.
   • DESTINATION_RUN_REGION: (optional) the Cloud Run location in which the destination Cloud Run function can be found. If not specified, it is assumed that the function is in the same region as the trigger.
   • The --event-filters="type=google.cloud.pubsub.topic.v1.messagePublished" flag is required and can't be changed. For a different event type, you must create a new trigger.
   • TOPIC_ID: the ID of the existing Pub/Sub topic. The topic must be in the same project as the trigger.
   • SERVICE_ACCOUNT_NAME: the name of your user-managed service account.
   • PROJECT_ID: your Google Cloud project ID.

   Notes:

   • Optionally, to specify a single event delivery attempt with no retries, use the --max-retry-attempts flag. The only valid value is 1. If you omit the flag, the standard retry behavior applies. For more information, see Retry events.
   • Other flags are available. For more information, see gcloud eventarc triggers create.

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.
• Learn how to configure retries.