Trigger Cloud Run with Eventarc events

Trigger Cloud Run with Eventarc events

About this codelab

Last updated Apr 12, 2023

Written by Mete Atamel

1. Introduction

Cloud Run allows you to run stateless containers in a fully managed environment. It is built from open-source Knative, letting you choose to run your containers either fully managed with Cloud Run, or in your Google Kubernetes Engine cluster with Cloud Run for Anthos.

Eventarc makes it easy to connect various services (Cloud Run, Cloud Functions, Workfklows) with events from a variety of sources. It allows you to build event-driven architectures in which microservices are loosely coupled and distributed. It also takes care of event ingestion, delivery, security, authorization, and error-handling for you which improves developer agility and application resilience.

In this codelab, you will learn about Eventarc. More specifically, you will listen to events from Pub/Sub, Cloud Storage, and Cloud Audit Logs with Eventarc and pass them to a Cloud Run service.

What you'll learn

• Vision of Eventarc
• Discover events in Eventarc
• Create a Cloud Run sink
• Create a trigger for Pub/Sub
• Create a trigger for Cloud Storage
• Create a trigger for Cloud Audit Logs
• Explore the Eventarc UI

2. Vision of Eventarc

Eventarc aims to deliver events from various Google, Google Cloud, and 3rd party event sources to Google Cloud event destinations.

Google Cloud sources	Event sources that are Google Cloud owned products
Google sources	Event sources that are Google-owned products such as Gmail, Hangouts, Android Management and more
Custom sources	Event sources that are not Google-owned products and are created by end-users themselves
3rd party sources	Event sources that are neither Google-owned nor customer-produced. This includes popular event sources such as Check Point CloudGuard, Datadog, ForgeRock, Lacework, etc. that are owned and maintained by 3rd party providers and partners.

Events are normalized to CloudEvents v1.0 format for cross-service interoperability. CloudEvents is a vendor-neutral open spec describing event data in common formats, enabling interoperability across services, platforms and systems.

3. Setup and Requirements

Self-paced environment setup

1. Sign-in to the Google Cloud Console and create a new project or reuse an existing one. If you don't already have a Gmail or Google Workspace account, you must create one.

• The Project name is the display name for this project's participants. It is a character string not used by Google APIs, and you can update it at any time.
• The Project ID must be unique across all Google Cloud projects and is immutable (cannot be changed after it has been set). The Cloud Console auto-generates a unique string; usually you don't care what it is. In most codelabs, you'll need to reference the Project ID (and it is typically identified as PROJECT_ID), so if you don't like it, generate another random one, or, you can try your own and see if it's available. Then it's "frozen" after the project is created.
• There is a third value, a Project Number which some APIs use. Learn more about all three of these values in the documentation.

Caution: A project ID must be globally unique and cannot be used by anyone else after you've selected it. You are the only user of that ID. If a project is deleted, that ID can never be used again.

Note: If you're using a Gmail account, you can leave the default location set to No organization. If you're using a Google Workspace account, then choose a location that makes sense for your organization.

2. Next, you'll need to enable billing in the Cloud Console in order to use Cloud resources/APIs. Running through this codelab shouldn't cost much, if anything at all. To shut down resources so you don't incur billing beyond this tutorial, follow any "clean-up" instructions found at the end of the codelab. New users of Google Cloud are eligible for the $300 USD Free Trial program.

Start Cloud Shell

While Google Cloud can be operated remotely from your laptop, in this codelab you will be using Google Cloud Shell, a command line environment running in the Cloud.

From the GCP Console click the Cloud Shell icon on the top right toolbar:

It should only take a few moments to provision and connect to the environment. When it is finished, you should see something like this:

This virtual machine is loaded with all the development tools you'll need. It offers a persistent 5GB home directory, and runs on Google Cloud, greatly enhancing network performance and authentication. All of your work in this lab can be done with simply a browser.

Before you begin

Inside Cloud Shell, make sure that your project ID is setup:

PROJECT_ID=your-project-id
gcloud config set project $PROJECT_ID

4. Deploy a Cloud Run service

Deploy a Cloud Run service to receive events. You will deploy Cloud Run's Hello container that logs the contents of CloudEvents.

First, enable required services for Cloud Run:

gcloud services enable run.googleapis.com

Deploy the hello container to Cloud Run:

REGION=us-central1
SERVICE_NAME=hello

gcloud run deploy $SERVICE_NAME \
  --allow-unauthenticated \
  --image=gcr.io/cloudrun/hello \
  --region=$REGION

On success, the command line displays the service URL. You can open the service URL in any browser window to double check that the service is now deployed.

5. Event Discovery

Before creating triggers in Eventarc, you can discover what the event sources are, the types of events they can emit, and how to configure triggers in order to consume them.

To see the list of different types of events:

gcloud beta eventarc attributes types list

NAME                                           DESCRIPTION
google.cloud.audit.log.v1.written              Cloud Audit Log written
google.cloud.pubsub.topic.v1.messagePublished  Cloud Pub/Sub message published
google.cloud.storage.object.v1.archived         Cloud Storage: Sent when a live version of an (object versioned) object is archived or deleted.
google.cloud.storage.object.v1.deleted          Cloud Storage: Sent when an object has been permanently deleted.
google.cloud.storage.object.v1.finalized        Cloud Storage: Sent when a new object (or a new generation of an existing object).
google.cloud.storage.object.v1.metadataUpdated  Cloud Storage: Sent when the metadata of an existing object changes.

To get more information about each event type:

gcloud beta eventarc attributes types describe google.cloud.audit.log.v1.written

attributes: type,serviceName,methodName,resourceName
description: 'Cloud Audit Log: Sent when a log is written.'
name: google.cloud.audit.log.v1.written

To see the list of services that emit a certain event type:

gcloud beta eventarc attributes service-names list --type=google.cloud.audit.log.v1.written

SERVICE_NAME                                DISPLAY_NAME
accessapproval.googleapis.com               Access Approval
accesscontextmanager.googleapis.com         Access Context Manager
admin.googleapis.com                        Google Workspace Admin
aiplatform.googleapis.com                   AI Platform (under Vertex AI)
apigee.googleapis.com                       Apigee
apigeeconnect.googleapis.com                Apigee Connect
...
workflows.googleapis.com                    Workflows

To see the list of method names (sub-events) that each service can emit:

gcloud beta eventarc attributes method-names list --type=google.cloud.audit.log.v1.written --service-name=workflows.googleapis.com

METHOD_NAME
google.cloud.workflows.v1.Workflows.CreateWorkflow
google.cloud.workflows.v1.Workflows.DeleteWorkflow
google.cloud.workflows.v1.Workflows.GetWorkflow
google.cloud.workflows.v1.Workflows.ListWorkflows
google.cloud.workflows.v1.Workflows.UpdateWorkflow
google.cloud.workflows.v1beta.Workflows.CreateWorkflow
google.cloud.workflows.v1beta.Workflows.DeleteWorkflow
google.cloud.workflows.v1beta.Workflows.GetWorkflow
google.cloud.workflows.v1beta.Workflows.ListWorkflows
google.cloud.workflows.v1beta.Workflows.UpdateWorkflow

6. Create a Pub/Sub trigger

One way of receiving events is through Cloud Pub/Sub. Any application can publish messages to Pub/Sub and these messages can be delivered to Cloud Run via Eventarc.

Setup

Before creating any triggers, enable required services for Eventarc:

gcloud services enable eventarc.googleapis.com

You also need a service account to be used by triggers. Create a service account:

SERVICE_ACCOUNT=eventarc-trigger-sa

gcloud iam service-accounts create $SERVICE_ACCOUNT

Create

Create a trigger to filter events published to the Pub/Sub topic to our deployed Cloud Run service:

TRIGGER_NAME=trigger-pubsub

gcloud eventarc triggers create $TRIGGER_NAME \
  --destination-run-service=$SERVICE_NAME \
  --destination-run-region=$REGION \
  --event-filters="type=google.cloud.pubsub.topic.v1.messagePublished" \
  --location=$REGION \
  --service-account=$SERVICE_ACCOUNT@$PROJECT_ID.iam.gserviceaccount.com

Test

Pub/Sub trigger creates a topic under the covers. Let's find it out and assign to a variable:

TOPIC_ID=$(gcloud eventarc triggers describe $TRIGGER_NAME --location $REGION --format='value(transport.pubsub.topic)')

Use gcloud to publish a message to the topic:

gcloud pubsub topics publish $TOPIC_ID --message="Hello World"

The Cloud Run service logs the body of the incoming message. You can view this in the Logs section of your Cloud Run instance:

Create with an existing Pub/Sub topic

By default, when you create a Pub/Sub trigger, Eventarc creates a topic under the covers for you to use as a transport topic between your application and a Cloud Run service. This is useful to easily and quickly create a Pub/Sub backed trigger but sometimes you want might to use an existing topic. Eventarc allows you to specify an existing Pub/Sub topic in the same project with --transport-topic gcloud flag.

To see how this works, create a Pub/Sub topic to use as transport topic:

TOPIC_ID=eventarc-topic

gcloud pubsub topics create $TOPIC_ID

Create a trigger:

TRIGGER_NAME=trigger-pubsub-existing

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

You can test the trigger by sending a message to the topic:

gcloud pubsub topics publish $TOPIC_ID --message="Hello again"

7. Create a Cloud Storage trigger

In this step, you will create a trigger to listen for events from Cloud Storage.

Setup

First, create a bucket to receive events from:

BUCKET_NAME=eventarc-gcs-$PROJECT_ID

gsutil mb -l $REGION gs://$BUCKET_NAME

Grant the eventarc.eventReceiver role, so the service account can be used in a Cloud Storage trigger:

gcloud projects add-iam-policy-binding $PROJECT_ID \
  --role roles/eventarc.eventReceiver \
  --member serviceAccount:$SERVICE_ACCOUNT@$PROJECT_ID.iam.gserviceaccount.com

You also need to add the pubsub.publisher role to the Cloud Storage service account for Cloud Storage triggers:

SERVICE_ACCOUNT_STORAGE=$(gsutil kms serviceaccount -p $PROJECT_ID)

gcloud projects add-iam-policy-binding $PROJECT_ID \
    --member serviceAccount:$SERVICE_ACCOUNT_STORAGE \
    --role roles/pubsub.publisher

Create

Create a trigger to route new file creation events from the bucket to your service:

TRIGGER_NAME=trigger-storage

gcloud eventarc triggers create $TRIGGER_NAME \
  --destination-run-service=$SERVICE_NAME \
  --destination-run-region=$REGION \
  --event-filters="type=google.cloud.storage.object.v1.finalized" \
  --event-filters="bucket=$BUCKET_NAME" \
  --location=$REGION \
  --service-account=$SERVICE_ACCOUNT@$PROJECT_ID.iam.gserviceaccount.com

Test

List all triggers to confirm that trigger was successfully created:

gcloud eventarc triggers list

Upload a file to the Cloud Storage bucket:

echo "Hello World" > random.txt
gsutil cp random.txt gs://$BUCKET_NAME/random.txt

If you check the logs of the Cloud Run service in Cloud Console, you should see the received event:

8. Create a Cloud Audit Logs trigger

Although Cloud Storage trigger is the better way to listen for Cloud Storage events, in this step, you create a Cloud Audit Log trigger to do the same.

Setup

In order to receive events from a service, you need to enable Cloud Audit Logs. From the Cloud Console, select IAM & Admin and Audit Logs from the upper left-hand menu. In the list of services, check Google Cloud Storage:

On the right hand side, make sure Admin, Read and Write are selected and click Save:

Create

Create a trigger to route new file creation events from the bucket to your service:

TRIGGER_NAME=trigger-auditlog-storage

gcloud eventarc triggers create $TRIGGER_NAME\
  --destination-run-service=$SERVICE_NAME \
  --destination-run-region=$REGION \
  --event-filters="type=google.cloud.audit.log.v1.written" \
  --event-filters="serviceName=storage.googleapis.com" \
  --event-filters="methodName=storage.objects.create" \
  --event-filters-path-pattern="resourceName=/projects/_/buckets/$BUCKET_NAME/objects/*" \
  --location=$REGION \
  --service-account=$SERVICE_ACCOUNT@$PROJECT_ID.iam.gserviceaccount.com

Note: Eventarc supports applying a path pattern when filtering. For example, you can filter on the optional resourceName field. In this case, you are filtering for all object creations under a specific bucket. See Understand path patterns for more details.

Test

Audit Logs triggers take a little bit of time to initialize. You can check that the trigger is created by listing all triggers:

gcloud eventarc triggers list

You should see that the ACTIVE field is Yes:

NAME                          TYPE                                       DESTINATION               ACTIVE
trigger-auditlog-storage  google.cloud.audit.log.v1.written              Cloud Run service: hello  Yes

Upload the same file to the Cloud Storage bucket as you did earlier:

gsutil cp random.txt gs://$BUCKET_NAME/random.txt

If you check the logs of the Cloud Run service in Cloud Console, you should see the received event:

9. Explore the Eventarc UI

In this step, you will explore the Eventarc UI in Google Cloud Console. In the Eventarc UI, you can get an overview of all the triggers, edit and delete them, and create new triggers from Google Cloud Console.

Go to the Eventarc section of Google Cloud:

You'll see the list of triggers you created earlier:

If you click on a trigger, you can see the details of the trigger, edit or delete it:

You can also create a new trigger by selecting Create trigger and filling in details of the trigger:

10. Congratulations!

Congratulations for completing the codelab.

What we've covered

• Vision of Eventarc
• Discover events in Eventarc
• Create a Cloud Run sink
• Create a trigger for Pub/Sub
• Create a trigger for Cloud Storage
• Create a trigger for Cloud Audit Logs
• Explore the Eventarc UI