Understand Eventarc locations

Cloud Audit Logs

Using Cloud Audit Logs triggers, you can connect any event source that emits audit logs to an event target. Cloud Audit Logs triggers are available in single-region locations and you can also create a global Eventarc trigger; however, triggers are not supported in dual-region and multi-region locations.

The ___location of the event source dictates the trigger ___location. Typically, this is a single-region ___location. For example, to capture Cloud Storage events from a bucket in the europe-west1 region with an audit logs trigger, create a trigger in the same ___location:

gcloud eventarc triggers create trigger-auditlog \
  --destination-run-service=hello \
  --destination-run-region=us-central1 \
  --___location=europe-west1 \
  --event-filters="type=google.cloud.audit.log.v1.written" \
  --event-filters="serviceName=storage.googleapis.com" \
  --event-filters="methodName=storage.objects.create" \
  --service-account=$PROJECT_NUMBER-compute@developer.gserviceaccount.com

As there's no filtering by bucket when you use a Cloud Audit Logs trigger, this will match all buckets in the europe-west1 region. (To filter by bucket, you can instead use a direct Cloud Storage trigger.)

Or, to match a dual-region or multi-region bucket such as eu, you can create a trigger with a global ___location and this will match all buckets in all regions for which the event filters match:

gcloud eventarc triggers create trigger-storage \
  --destination-run-service=hello \
  --destination-run-region=us-central1 \
  --___location=global \
  --event-filters="type=google.cloud.storage.object.v1.finalized" \
  --event-filters="bucket=my-bucket-in-europe-west1-region" \
  --service-account=$PROJECT_NUMBER-compute@developer.gserviceaccount.com

Cloud Storage

Cloud Storage triggers respond to events inside a Cloud Storage bucket—object creation, deletion, archiving, and metadata updates. Cloud Storage triggers are available in single-region, dual-region, and multi-region locations; you cannot create a global Eventarc trigger.

The ___location of the Cloud Storage bucket dictates the ___location of the Eventarc trigger, and they must match. In the following example, the trigger ___location matches that of the Cloud Storage bucket (the eu multi-region ___location):

gcloud eventarc triggers create trigger-storage \
  --destination-run-service=hello \
  --destination-run-region=us-central1 \
  --___location=eu \
  --event-filters="type=google.cloud.storage.object.v1.finalized" \
  --event-filters="bucket=my-bucket-in-eu-multi-region" \
  --service-account=$PROJECT_NUMBER-compute@developer.gserviceaccount.com

If the bucket and trigger regions don't match, you will see an error similar to the following:

ERROR: (gcloud.eventarc.triggers.create) INVALID_ARGUMENT: The request was
invalid: Bucket "my-bucket-in-eu-multi-region" ___location "eu" does not match
trigger ___location "europe-west1". Try again by creating the trigger in "eu".

Pub/Sub

A Pub/Sub trigger connects a Pub/Sub topic to an event target. Pub/Sub triggers are only available in single-region locations and you cannot create a global Eventarc trigger.

Although Pub/Sub topics are global and not tied to a single region, when you create a Pub/Sub trigger, you must specify a region for it using the --___location flag:

gcloud eventarc triggers create trigger-pubsub \
--destination-run-service=hello \
--destination-run-region=us-central1 \
--___location=us-central1 \
--event-filters="type=google.cloud.pubsub.topic.v1.messagePublished" \
--transport-topic=projects/your-projectid/topics/your-topic

Eventarc configures geofencing so that Pub/Sub events persist only in the specified ___location. You can also use regional Pub/Sub service endpoints to publish to the topic so that all of the data stays in a single region.