This tutorial shows how to deploy a containerized application using an
authenticated Cloud Run service that receives events using
Pub/Sub. Pub/Sub is a fully-managed real-time messaging
service that lets you send and receive messages between independent
applications.


> [!NOTE]
> **Note:** All Cloud Run services are deployed privately by default, which means that they can't be accessed without providing authentication credentials in the request. For projects with [domain restricted sharing organization policies](https://docs.cloud.google.com/resource-manager/docs/organization-policy/restricting-domains), use an authenticated Cloud Run target service rather than one that allows [public access](https://docs.cloud.google.com/run/docs/authenticating/public.md.txt).

<br />

## Objectives

In this tutorial, you will:

1. Deploy an event receiver service to Cloud Run that
   requires authenticated invocations.

2. Create an Eventarc trigger that connects a
   Pub/Sub topic to the Cloud Run
   service.

3. Publish a message to the Pub/Sub topic to generate an event.

4. View the event in the Cloud Run logs.

## Costs


In this document, you use the following billable components of Google Cloud:


- [Artifact Registry](https://docs.cloud.google.com/artifact-registry)
- [Cloud Build](https://docs.cloud.google.com/build)
- [Cloud Run](https://docs.cloud.google.com/run)
- [Eventarc](https://docs.cloud.google.com/eventarc)
- [Pub/Sub](https://docs.cloud.google.com/pubsub)


To generate a cost estimate based on your projected usage,
use the [pricing calculator](https://docs.cloud.google.com/products/calculator).
New Google Cloud users might be eligible for a [free trial](https://docs.cloud.google.com/free).

<br />

## Before you begin

Security constraints defined by your organization might prevent you from completing the
following steps. For troubleshooting information, see
[Develop applications in a constrained Google Cloud environment](https://docs.cloud.google.com/resource-manager/docs/organization-policy/develop-apps-constrained-environment).

1. Update Google Cloud CLI components:

   ```bash
   gcloud components update
   ```
2. Sign in using your account:

   ```bash
   gcloud auth login
   ```
3. Enable the APIs:

   ```bash
   gcloud services enable artifactregistry.googleapis.com \
       cloudbuild.googleapis.com \
       eventarc.googleapis.com \
       pubsub.googleapis.com \
       run.googleapis.com
   ```
4. Set the configuration variables used in this tutorial:

   ```bash
   export REGION=us-central1
   gcloud config set run/region ${REGION}
   gcloud config set run/platform managed
   gcloud config set eventarc/location ${REGION}
   export SERVICE_NAME=trigger-pubsub
   ```
5. If you are the project creator, you are granted the
   [basic Owner role](https://docs.cloud.google.com/iam/docs/roles-overview.md.txt#basic)
   (`roles/owner`). By default, this Identity and Access Management (IAM) role
   includes the permissions necessary for full access to most Google Cloud
   resources and you can skip this step.

   If you are not the project creator, required permissions must be granted on
   the project to the appropriate *principal*. For example, a principal can be
   a Google Account (for end users) or a service account (for applications and
   compute workloads). For more information, see the
   [Roles and permissions](https://docs.cloud.google.com/eventarc/docs/all-roles-permissions.md.txt) page
   for your event destination.

   Note that by default,
   [Cloud Build
   permissions include permissions to upload and download Artifact Registry
   artifacts](https://docs.cloud.google.com/artifact-registry/docs/access-control#gcp).

   #### Required permissions


   To get the permissions that
   you need to complete this tutorial,

   ask your administrator to grant you the
   following IAM roles on your project:

   - [Cloud Build Editor](https://docs.cloud.google.com/iam/docs/roles-permissions/cloudbuild.md.txt#cloudbuild.builds.editor) (`roles/cloudbuild.builds.editor`)
   - [Cloud Run Admin](https://docs.cloud.google.com/iam/docs/roles-permissions/run.md.txt#run.admin) (`roles/run.admin`)
   - [Eventarc Admin](https://docs.cloud.google.com/iam/docs/roles-permissions/eventarc.md.txt#eventarc.admin) (`roles/eventarc.admin`)
   - [Logs View Accessor](https://docs.cloud.google.com/iam/docs/roles-permissions/logging.md.txt#logging.viewAccessor) (`roles/logging.viewAccessor`)
   - [Project IAM Admin](https://docs.cloud.google.com/iam/docs/roles-permissions/resourcemanager.md.txt#resourcemanager.projectIamAdmin) (`roles/resourcemanager.projectIamAdmin`)
   - [Pub/Sub Publisher](https://docs.cloud.google.com/iam/docs/roles-permissions/pubsub.md.txt#pubsub.publisher) (`roles/pubsub.publisher`)
   - [Service Account Admin](https://docs.cloud.google.com/iam/docs/roles-permissions/iam.md.txt#iam.serviceAccountAdmin) (`roles/iam.serviceAccountAdmin`)
   - [Service Account User](https://docs.cloud.google.com/iam/docs/roles-permissions/iam.md.txt#iam.serviceAccountUser) (`roles/iam.serviceAccountUser`)
   - [Service Usage Admin](https://docs.cloud.google.com/iam/docs/roles-permissions/serviceusage.md.txt#serviceusage.serviceUsageAdmin) (`roles/serviceusage.serviceUsageAdmin`)
   - [Storage Admin](https://docs.cloud.google.com/iam/docs/roles-permissions/storage.md.txt#storage.admin) (`roles/storage.admin`)


   For more information about granting roles, see [Manage access to projects, folders, and organizations](https://docs.cloud.google.com/iam/docs/granting-changing-revoking-access.md.txt).


   You might also be able to get
   the required permissions through [custom
   roles](https://docs.cloud.google.com/iam/docs/creating-custom-roles) or other [predefined
   roles](https://docs.cloud.google.com/iam/docs/roles-overview#predefined).
6. Make note of the [Compute Engine
   default service account](https://docs.cloud.google.com/iam/docs/service-account-types#default) as you will 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:

   ```bash
   PROJECT_NUMBER-compute@developer.gserviceaccount.com
   ```

   Replace `PROJECT_NUMBER` with your Google Cloud
   project number. You can find your project number on the
   [Welcome](https://console.cloud.google.com/welcome)
   page of the Google Cloud console or by running the following command:

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

   For production environments, we strongly recommend
   [creating a new service account](https://docs.cloud.google.com/iam/docs/service-accounts-create.md.txt)
   and granting it one or more IAM roles that contain the
   [minimum permissions required](https://docs.cloud.google.com/iam/docs/best-practices-service-accounts.md.txt#limit-service-account-privileges)
   and follow the principle of [least privilege](https://docs.cloud.google.com/iam/docs/using-iam-securely.md.txt#least_privilege).

   > [!NOTE]
   > **Note:**
   >
   >
   > The [`iam.automaticIamGrantsForDefaultServiceAccounts` organization policy constraint](https://docs.cloud.google.com/resource-manager/docs/organization-policy/restricting-service-accounts#disable_service_account_default_grants)
   > 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](https://docs.cloud.google.com/iam/docs/granting-changing-revoking-access.md.txt)
   > 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](https://docs.cloud.google.com/policy-intelligence/docs/simulate-iam-policies.md.txt) to see the impact of
   > the change, and then [grant and revoke the
   > appropriate roles](https://docs.cloud.google.com/iam/docs/granting-changing-revoking-access).

7. 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](https://docs.cloud.google.com/run/docs/securing/managing-access#control-service-or-job-access); however, for testing purposes, grant the [Cloud Run
   Invoker role](https://docs.cloud.google.com/iam/docs/roles-permissions/run#run.invoker) (`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.

   ```bash
   gcloud projects add-iam-policy-binding PROJECT_ID \
       --member=serviceAccount:PROJECT_NUMBER-compute@developer.gserviceaccount.com \
       --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 public access or set the proper Authorization
   header.`
8. 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](https://docs.cloud.google.com/iam/docs/roles-permissions/iam#iam.serviceAccountTokenCreator) (`roles/iam.serviceAccountTokenCreator`) to the service agent. Otherwise, this role is granted by default:

   ```bash
   gcloud projects add-iam-policy-binding PROJECT_ID \
       --member=serviceAccount:service-PROJECT_NUMBER@gcp-sa-pubsub.iam.gserviceaccount.com \
       --role=roles/iam.serviceAccountTokenCreator
   ```

## Create an Artifact Registry standard repository

Create an Artifact Registry standard repository to store your container image:

```bash
gcloud artifacts repositories create REPOSITORY \
    --repository-format=docker \
    --location=$REGION
```

Replace `REPOSITORY` with a unique name for the
repository.

## Deploy an event receiver to Cloud Run

Deploy a Cloud Run service that logs the contents of an
event.

1. Clone the GitHub repository:

   ### Node.js

   ```bash
   git clone https://github.com/GoogleCloudPlatform/nodejs-docs-samples.git
   ```


   Alternatively, you can
   [download the sample](https://github.com/GoogleCloudPlatform/nodejs-docs-samples/archive/master.zip)
   as a zip file and extract it.

   ### Python

   ```bash
   git clone https://github.com/GoogleCloudPlatform/python-docs-samples.git
   ```


   Alternatively, you can
   [download the sample](https://github.com/GoogleCloudPlatform/python-docs-samples/archive/master.zip)
   as a zip file and extract it.

   ### Go

   ```bash
   git clone https://github.com/GoogleCloudPlatform/golang-samples.git
   ```


   Alternatively, you can
   [download the sample](https://github.com/GoogleCloudPlatform/golang-samples/archive/master.zip)
   as a zip file and extract it.

   ### Java

   ```bash
   git clone https://github.com/GoogleCloudPlatform/java-docs-samples.git
   ```


   Alternatively, you can
   [download the sample](https://github.com/GoogleCloudPlatform/java-docs-samples/archive/master.zip)
   as a zip file and extract it.

   ### Ruby

   ```bash
   git clone https://github.com/GoogleCloudPlatform/ruby-docs-samples.git
   ```


   Alternatively, you can
   [download the sample](https://github.com/GoogleCloudPlatform/ruby-docs-samples/archive/master.zip)
   as a zip file and extract it.

   ### C#

   ```bash
   git clone https://github.com/GoogleCloudPlatform/dotnet-docs-samples.git
   ```


   Alternatively, you can
   [download the sample](https://github.com/GoogleCloudPlatform/dotnet-docs-samples/archive/master.zip)
   as a zip file and extract it.
2. Change to the directory that contains the Cloud Run
   sample code:

   ### Node.js

   ```bash
   cd nodejs-docs-samples/eventarc/pubsub/
   ```

   ### Python

   ```bash
   cd python-docs-samples/eventarc/pubsub/
   ```

   ### Go

   ```bash
   cd golang-samples/eventarc/pubsub/
   ```

   ### Java

   ```bash
   cd java-docs-samples/eventarc/pubsub/
   ```

   ### Ruby

   ```bash
   cd ruby-docs-samples/eventarc/pubsub/
   ```

   ### C#

   ```bash
   cd dotnet-docs-samples/eventarc/pubsub/
   ```
3. Build the container and upload it to Cloud Build:

   ```bash
   gcloud builds submit --tag $REGION-docker.pkg.dev/PROJECT_ID/REPOSITORY/trigger-pubsub:v1
   ```
4. Deploy the container image to Cloud Run:

   ```bash
   gcloud run deploy ${SERVICE_NAME} \
       --image $REGION-docker.pkg.dev/PROJECT_ID/REPOSITORY/trigger-pubsub:v1
   ```
5. At the *Allow unauthenticated invocations to
   trigger-pubsub (y/N)?* prompt, respond `n` for "No".

> [!NOTE]
> **Note:** Based on the required level of network access to the Cloud Run service, you can also set the [ingress flag](https://docs.cloud.google.com/sdk/gcloud/reference/run/services/update.md.txt#--ingress).

When you see the Cloud Run service URL, the deployment is complete.

## Create an Eventarc trigger

When a message is published to the Pub/Sub topic, the event
triggers the Cloud Run service.

> [!NOTE]
> **Note:** By default, Pub/Sub subscriptions created for Eventarc persist regardless of activity and don't expire. To change the inactivity duration, see [Subscription properties](https://docs.cloud.google.com/pubsub/docs/subscription-properties.md.txt).

1. Create a trigger to listen for Pub/Sub messages:

   ### New Pub/Sub topic

   ```bash
     gcloud eventarc triggers create ${SERVICE_NAME} \
         --destination-run-service=${SERVICE_NAME} \
         --destination-run-region=${REGION} \
         --location=${REGION} \
         --event-filters="type=google.cloud.pubsub.topic.v1.messagePublished" \
         --service-account=PROJECT_NUMBER-compute@developer.gserviceaccount.com
   ```

   This creates a new Pub/Sub topic and a trigger for it called
   `trigger-pubsub`.

   ### Existing Pub/Sub topic

   ```bash
     gcloud eventarc triggers create ${SERVICE_NAME} \
         --destination-run-service=${SERVICE_NAME} \
         --destination-run-region=${REGION} \
         --location=${REGION} \
         --event-filters="type=google.cloud.pubsub.topic.v1.messagePublished" \
         --transport-topic=projects/PROJECT_ID/topics/TOPIC_ID \
         --service-account=PROJECT_NUMBER-compute@developer.gserviceaccount.com
   ```

   Replace the following:
   - `PROJECT_ID`: your Google Cloud project ID
   - `TOPIC_ID`: the ID of the existing Pub/Sub topic

   This creates a trigger called `trigger-pubsub` for the existing
   Pub/Sub topic.


   Note that when creating an Eventarc trigger for the first
   time in a Google Cloud project, there might be a delay in provisioning
   the Eventarc service agent. This issue can usually be resolved
   by attempting to create the trigger again. For more information, see
   [Permission denied errors](https://docs.cloud.google.com/eventarc/docs/troubleshooting.md.txt#trigger-error).

   <br />

2. Confirm that the trigger was successfully created. Note that although your
   trigger is created immediately, it can take up to two minutes for a trigger
   to be fully functional.

   <br />

   ```bash
   gcloud eventarc triggers list --location=${REGION}
   ```

   <br />

   The returned trigger status should be `ACTIVE: Yes`.

## Generate and view an event

Publish a message to a Pub/Sub topic to generate an event and
trigger the Cloud Run service. The Cloud Run
service logs the messages on the service logs.

1. Find and set the Pub/Sub topic as an environment variable:

   ```bash
   export TOPIC_ID=$(gcloud eventarc triggers describe ${SERVICE_NAME} \
       --format='value(transport.pubsub.topic)')
   ```
2. Send a message to the Pub/Sub topic to generate an event:

   ```bash
   gcloud pubsub topics publish $TOPIC_ID --message "Hello there"
   ```

   The event is sent to the Cloud Run service, which
   logs the event message.
3. View the event-related log entries created by your service:

   ```
   gcloud logging read 'textPayload: "Hello there!"'
   ```

   The log entry should be similar to the following:

   ```
   textPayload: 'Hello, Hello there!'
   ```

Logs might take a few moments to appear. If you don't see them immediately,
check again after a minute.

## Clean up

To avoid incurring charges such as
[storing the container image in Artifact Registry](https://cloud.google.com/artifact-registry/pricing),
[storing files in your Cloud Storage bucket](https://cloud.google.com/storage/pricing), and
triggering [Eventarc](https://cloud.google.com/eventarc/pricing), you can delete the
resources that you created for this tutorial:

1. [Delete the Cloud Run service](https://docs.cloud.google.com/run/docs/managing/services.md.txt#delete).

2. [Delete your container image](https://docs.cloud.google.com/artifact-registry/docs/docker/manage-images.md.txt#deleting_images).

3. [Delete the Eventarc trigger](https://docs.cloud.google.com/eventarc/docs/managing-triggers.md.txt#deleting_triggers).

Alternatively, you can delete your Google Cloud project. Deleting your
Google Cloud project stops billing for all the resources used within that
project.

> [!CAUTION]
> **Caution** : Deleting a project has the following effects:
>
> - **Everything in the project is deleted.** If you used an existing project for the tasks in this document, when you delete it, you also delete any other work you've done in the project.
> - **Custom project IDs are lost.** When you created this project, you might have created a custom project ID that you want to use in the future. To preserve the URLs that use the project ID, such as an `appspot.com` URL, delete selected resources inside the project instead of deleting the whole project.

Delete a Google Cloud project:

```
gcloud projects delete PROJECT_ID
```

## What's next

- [Receive a Pub/Sub event using an unauthenticated Cloud Run service](https://docs.cloud.google.com/eventarc/standard/docs/run/create-trigger-pub-sub-gcloud.md.txt)
- [Build containers](https://docs.cloud.google.com/run/docs/building/containers.md.txt)
- [Create a trigger to route Pub/Sub events to Cloud Run](https://docs.cloud.google.com/eventarc/standard/docs/run/route-trigger-cloud-pubsub.md.txt)
- [Develop Cloud Run services](https://docs.cloud.google.com/run/docs/developing.md.txt)