Create triggers from Cloud Storage events

In Cloud Run, you can trigger services from Cloud Storage using Eventarc, in response to changes in Cloud Storage.

When you specify a Cloud Storage trigger for your service, you choose an event type and specify a Cloud Storage bucket. As a result of this trigger, your service is called whenever a change occurs on an object (file) within the specified bucket.

For your service to be triggered by an event on a Cloud Storage bucket, the service and the bucket must be in the same Google Cloud project.

For detailed instructions and code samples for creating triggers from Cloud Storage events, refer to the following tutorials:

• Trigger services from Cloud Storage using Eventarc

• Trigger functions from Cloud Storage using Eventarc. You can also find sample code in the Google Cloud console that demonstrates how to trigger a function in response to Cloud Storage events, after deploying your Cloud Run function with a Cloud Storage trigger.

Supported Cloud Storage event types

Cloud Run supports the following Cloud Storage event types:

Event	Event type	Description
Object finalized	google.cloud.storage.object.v1.finalized (through Eventarc)	Occurs when you create a new object, or overwrite an existing object, and Cloud Storage creates a new generation of that object.
Object deleted	google.cloud.storage.object.v1.deleted (through Eventarc)	Occurs when an object is soft deleted. For more information, see Soft delete.
Object archived	google.cloud.storage.object.v1.archived (through Eventarc)	Occurs when a live version of an object becomes a noncurrent version. For more information, see Object Versioning.
Object metadata updated	google.cloud.storage.object.v1.metadataUpdated (through Eventarc)	Occurs when you change the metadata of an existing object.

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, Pub/Sub, and Cloud Storage 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 Cloud Storage 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)
• Storage Admin (roles/storage.admin)

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 Cloud Storage 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 Cloud Storage 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.storage.object.v1.finalized from the Event type list. Your trigger configuration varies depending on the supported event type. For more information, see Event types.

   5. In the Bucket field, click Browse to select a Cloud Storage bucket for the trigger to monitor. Changes to objects within this bucket will 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=EVENT_FILTER_TYPE" \
       --event-filters="bucket=BUCKET" \
       --service-account=SERVICE_ACCOUNT_NAME@PROJECT_ID.
   

   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.
   • EVENT_FILTER_TYPE: the identifier of the event. An event is generated when an API call for the method succeeds. For long-running operations, the event is only generated at the end of the operation, and only if the action is performed successfully. For a list of supported event types, see Google event types supported by Eventarc.
   • BUCKET: the globally unique identifier of the Cloud Storage bucket.
   • SERVICE_ACCOUNT_NAME: the name of your user-managed service account.
   • PROJECT_ID: your Google Cloud project ID.

   Notes:

   • The --event-filters="type=EVENT_FILTER_TYPE" flag is required. If no other event filter is set, events for all resources are matched.
   • EVENT_FILTER_TYPE can't be changed after creation. To change EVENT_FILTER_TYPE, create a new trigger and delete the old one.
   • Each trigger can have multiple event filters, comma delimited in one --event-filters=[ATTRIBUTE=VALUE,...] flag, or you can repeat the flag to add more filters. Only events that match all the filters are sent to the destination. Wildcards and regular expressions are not supported; however, when using the --event-filters-path-pattern flag, you can define a resource path pattern.
   • 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 Cloud Storage 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 Cloud Storage 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.storage.object.v1.finalized from the Event type list. Your trigger configuration varies depending on the supported event type. For more information, see Event types.

   5. Leave the Event data content type field as is.

   6. In the Bucket field, click Browse to select a Cloud Storage bucket for the trigger to monitor. Changes to objects within this bucket will trigger calls to your function.

   7. 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.

   8. 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.

   9. 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.

   10. 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=EVENT_FILTER_TYPE" \
       --event-filters="bucket=BUCKET" \
       --service-account=SERVICE_ACCOUNT_NAME@PROJECT_ID.
   

   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.
   • EVENT_FILTER_TYPE: the identifier of the event. An event is generated when an API call for the method succeeds. For long-running operations, the event is only generated at the end of the operation, and only if the action is performed successfully. For a list of supported event types, see Google event types supported by Eventarc.
   • BUCKET: the globally unique identifier of the Cloud Storage bucket.
   • SERVICE_ACCOUNT_NAME: the name of your user-managed service account.
   • PROJECT_ID: your Google Cloud project ID.

   Notes:

   • The --event-filters="type=EVENT_FILTER_TYPE" flag is required. If no other event filter is set, events for all resources are matched.
   • EVENT_FILTER_TYPE can't be changed after creation. To change EVENT_FILTER_TYPE, create a new trigger and delete the old one.
   • Each trigger can have multiple event filters, comma delimited in one --event-filters=[ATTRIBUTE=VALUE,...] flag, or you can repeat the flag to add more filters. Only events that match all the filters are sent to the destination. Wildcards and regular expressions are not supported; however, when using the --event-filters-path-pattern flag, you can define a resource path pattern.
   • 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.

Event delivery

Cloud Storage triggers are implemented with Pub/Sub notifications for Cloud Storage. Events are subject to Pub/Sub notification delivery guarantees.

A Cloud Storage bucket can have up to 10 notification configurations set to trigger for a specific event. Exceeding the bucket's notifications limits will cause further function deployments to fail with an error like the following:

Cloud Storage bucket ...: Pub/Sub notification limit reached

You can work around this limitation by managing your own Pub/Sub topic and registering it for Cloud Storage notifications of the type you want your function to respond to. For example, you could configure a single notification for your chosen event (such as object creation) to a Pub/Sub topic. Then, have as many function subscribers as needed to the topic process the event and fan it out to multiple destinations. For example:

1. Create your own Pub/Sub topic.
2. Create a single notification configuration on your Cloud Storage bucket that triggers on a specific event (such as OBJECT_FINALIZE for object creation) and sends the event to your single Pub/Sub topic.
3. Create a function (or functions) triggered by your Pub/Sub topic.

This results in one Cloud Storage notification configuration, one Pub/Sub topic, and as many functions as you need (within the very high delivery limits allowed by Pub/Sub).

See Cloud Storage Quotas and limits to learn more about Cloud Storage limitations.

Next steps

• Learn how to trigger with events.
• Learn how to trigger services from Cloud Storage using Eventarc.
• Learn how to trigger functions from Cloud Storage using Eventarc.