Test a Cloud Run service locally

During development, you can run and test your container image locally, prior to deploying. You can use Cloud Code or Docker installed locally to run and test locally, including running locally with access to Google Cloud services.

Before you begin

If this is the first time you're trying to run locally, you might not have all the permissions needed to access the image from your supported container registry you're using.

Check your supported container registry documentation about to how to get access. You can configure Docker to get access to Artifact Registry using the gcloud CLI credential helper 

gcloud auth configure-docker LOCATION-docker.pkg.dev
 .

Test locally

You can test locally using Docker, Docker with Google Cloud Access, the Cloud Code emulator or the Google Cloud CLI. Select the appropriate tab for instructions.

Docker

To test your container image locally using Docker:

  1. Use the Docker command:

    PORT=8080 && docker run -p 9090:${PORT} -e PORT=${PORT} IMAGE_URL

    Replace IMAGE_URL with a reference to the container image, for example, us-docker.pkg.dev/cloudrun/container/hello:latest. If you use Artifact Registry, the repository REPO_NAME must already be created. The URL has the shape LOCATION-docker.pkg.dev/PROJECT_ID/REPO_NAME/PATH:TAG .

    The PORT environment variable specifies the port your application will use to listen for HTTP or HTTPS requests. This is a requirement from the Container runtime contract. In this example, we use port 8080.

  2. Open http://localhost:9090 in your browser.

If you are new to working with containers, you may want to review the Docker Getting Started guide. To learn more about Docker commands, refer to the Docker documentation.

Docker with Google Cloud Access

If you are using Google Cloud client libraries to integrate your application with Google Cloud services, and have not yet secured those services to control external access, you can set up your local container to authenticate with Google Cloud services using Application Default Credentials.

To run locally:

  1. Refer to Getting Started with Authentication for instructions on generating, retrieving, and configuring your Service Account credentials.

  2. The following Docker run flags inject the credentials and configuration from your local system into the local container:

    1. Use the --volume (-v) flag to inject the credential file into the container (assumes you have already set your GOOGLE_APPLICATION_CREDENTIALS environment variable on your machine): 
      -v $GOOGLE_APPLICATION_CREDENTIALS:/tmp/keys/FILE_NAME.json:ro
    2. Use the --environment (-e) flag to set the GOOGLE_APPLICATION_CREDENTIALS variable inside the container: 
      -e GOOGLE_APPLICATION_CREDENTIALS=/tmp/keys/FILE_NAME.json

  3. Optionally, use this fully configured Docker run command:

    PORT=8080 && docker run \
-p 9090:${PORT} \
-e PORT=${PORT} \
-e K_SERVICE=dev \
-e K_CONFIGURATION=dev \
-e K_REVISION=dev-00001 \
-e GOOGLE_APPLICATION_CREDENTIALS=/tmp/keys/FILE_NAME.json \
-v $GOOGLE_APPLICATION_CREDENTIALS:/tmp/keys/FILE_NAME.json:ro \
IMAGE_URL

    Note that the path 

    /tmp/keys/FILE_NAME.json
     shown in the example above is a reasonable location to place your credentials inside the container.

    However, other directory locations will also work. The crucial requirement is that the GOOGLE_APPLICATION_CREDENTIALS environment variable must match the bind mount location inside the container.

    Note also, that with some Google Cloud services, you may want to use an alternate configuration to isolate local troubleshooting from production performance and data.

Cloud Code emulator

The Cloud Code plugin for VS Code and JetBrains IDEs lets you locally run and debug your container image in a Cloud Run emulator within your IDE. The emulator allows you configure an environment that is representative of your service running on Cloud Run.

You can configure properties like CPU and memory allocation, specify environment variables, and set Cloud SQL database connections.

  1. Install Cloud Code for VS Code or a JetBrains IDE.
  2. Follow the instructions for locally developing and debugging within your IDE.
  3. VS Code: Locally developing and debugging
  4. IntelliJ: Locally developing and debugging

gcloud CLI

Google Cloud CLI contains a local development environment for emulating Cloud Run that can build a container from source, run the container on your local machine, and automatically rebuild the container upon source code changes.

To start the local development environment:

  1. Change directory to the directory containing the source code of your service.

  2. Invoke the command: 

    gcloud beta code dev
     If a Dockerfile is present in the local directory, it is used to build the container. If no Dockerfile is present, the container is built with Google Cloud's buildpacks.

To see your service running, visit http://localhost:8080/ in your browser. If you specified a custom port with the --local-port option, remember to open your browser to that port.

To stop the local server:

  • Mac OS and Linux: Control-C
  • Windows: Control-Break

Customize the service configuration

You can customize the Cloud Run configuration of the service running locally using a YAML file. The YAML format is the same that can be used to deploy a Cloud Run service, but only supports a subset of the Cloud Run service settings. gcloud beta code dev looks for and uses any file ending in *.service.dev.yaml in the current directory. If none are found, it will use any file ending with *.service.yaml.

You can configure the following settings for local development:

The container image field is not required for local development, because the image is built and provided to the service when the command is run.

You can use the following example service.dev.yaml file for local development: 

  apiVersion: serving.knative.dev/v1
  kind: Service
  metadata:
    name: my-service-name
  spec:
    template:
      spec:
        containers:
        - env:
          - name: FOO
            value: bar

Test using credentials

To give permission to the container to use Google Cloud services, you must give the container an access credential.

  • To give the container access to a credential using your own account, log in using gcloud and use the --application-default-credential flag: 

    gcloud auth application-default login
gcloud beta code dev --dockerfile=PATH_TO_DOCKERFILE --application-default-credential

  • To give the application credentials as a service account, use the --service-account flag: 

    gcloud beta code dev --dockerfile=PATH_TO_DOCKERFILE --service-account=SERVICE_ACCOUNT_EMAIL

    The --service-account flag causes a service account key to be downloaded and cached locally. The user is responsible for keeping the key secure and deleting it when it is no longer needed.

Confirm that your code is running locally

When you test locally on Cloud Run, you can confirm in your code that your container is running locally by checking the K_REVISION environment variable, which Cloud Run makes available to all containers.

Docker

To confirm you are running your code locally on Google Cloud CLI you can attempt to query the K_REVISION environment variable but as it has not been set no value will be present.

Docker with Google Cloud Access

If you used the exact values from the above section in Step 3 to confirm you are running your code locally on Google Cloud CLI you can query the K_REVISION environment variable and look for the value dev-00001 to confirm it is running locally.

Cloud Code emulator

To confirm you are running your code locally on Cloud Code you can query the K_REVISION environment variable and look for a value of local to confirm it is running locally.

gcloud CLI

To confirm you are running your code locally on Google Cloud CLI you can query the K_REVISION environment variable and look for a value that begins with dev- to confirm it is running locally.

What's next