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Testing and deploying your application

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Region ID

The REGION_ID is an abbreviated code that Google assigns based on the region you select when you create your app. The code does not correspond to a country or province, even though some region IDs may appear similar to commonly used country and province codes. For apps created after February 2020, REGION_ID.r is included in App Engine URLs. For existing apps created before this date, the region ID is optional in the URL.

Learn more about region IDs.

Learn how to run your application locally, deploy it, and test on App Engine.

Running locally

To test your application's functionality before deploying, run your application in your local environment with the development tools that you usually use.

Deploying your application

Deploy your application to App Engine using the gcloud app deploy command.

The deployment command automatically builds a container image by using the Cloud Build service and then deploys that image to the App Engine flexible environment. The container will include any local modifications that you've made to the runtime image.

To programmatically deploy your apps, use the Admin API.

Before you begin

Before you can deploy your application:

Deploying a service

You deploy your application to App Engine by deploying versions of your application's services and each of their configuration files.

  • You can deploy the other configuration files of your service by targeting and deploying each file separately. For example:

    gcloud app deploy cron.yaml
    gcloud app deploy dispatch.yaml
    gcloud app deploy index.yaml
  • To specify a custom version ID, use the --version flag.

  • To prevent traffic from being automatically routed to the new version, use the --no-promote flag.

  • To deploy to a specific Cloud project, use the --project flag.

For example, to deploy the service defined by app.yaml to a specific Cloud project, assign it a custom version ID, and prevent traffic from being routed to the new version:

gcloud app deploy --project PROJECT_ID --version VERSION_ID --no-promote

For more information about this command, see the gcloud app deploy reference.

Ignoring files

You can use a .gcloudignore file to specify files and directories not to upload to Google Cloud when you deploy your services. This is useful for ignoring build artifacts and other files that do not need to be uploaded with your deployment.

Learn more about the syntax of the .gcloudignore file in the gcloud reference.

Manually building a container for deployment

To build your container images outside of Google Cloud Platform, you must first upload your images to a container image repository before you can deploy your images to App Engine with the gcloud app deploy command.

For example, if you build your container images locally with Docker, you can push those images to Google Container Registry and then specify the URL of your image in the --image-url flag of the command:

gcloud app deploy --image-url

Using automated continuous deployment pipelines

You can use Cloud Build to automate deployments in continuous deployment pipelines. For more information, see Deploying artifacts, and Automating Builds using Build Triggers in the Cloud Build documentation.

Docker base images

Viewing your application

After you deploy your application to App Engine, you can run the following command to launch your browser and view it at

gcloud app browse

Testing on App Engine

Before configuring a new version to receive traffic, you can test it on App Engine. For example, to test a new version of your default service:

  1. Deploy your new version and include the --no-promote flag:

    gcloud app deploy --no-promote
  2. Access your new version by navigating to the following URL:

    Now you can test your new version in the App Engine runtime environment. You can debug your application by viewing its logs in the Google Cloud console Logs Explorer. For more information, see Writing Application Logs.

    Requests sent to will still be routed to the version previously configured to receive traffic.

  3. When you want to send traffic to the new version, use the Google Cloud console to migrate traffic:

    Manage versions

    Select the version you just deployed and click Migrate traffic.

You can use the same process to test new versions of other services by replacing default in the URL with your service's name:

For more information about targeting specific services and versions, see How Requests are Routed.

Using Cloud Trace

Cloud Trace is useful for understanding how requests propagate through your application. You can inspect detailed latency information for a single request or view aggregate latency for your entire application.

To view trace details in Cloud Trace, you can follow Viewing trace details. In the Trace list, you can use the filters to filter by your specific App Engine service and version.


The following are common error messages that you might encounter when deploying apps:

PERMISSION_DENIED: Operation not allowed
The "appengine.applications.create" permission is required.
If the Cloud project does not include the required App Engine application, the gcloud app deploy command can fail when it tries to run the gcloud app create command. Only accounts with Owner role have the necessary permissions to create App Engine applications.
502 Bad Gateway
The Cloud project can fail to start if the app.yaml is misconfigured. Check the app logs for more detailed error messages.
[13] An internal error occurred while creating a Cloud Storage bucket.

App Engine creates a default Cloud Storage multi-regional bucket on your behalf, on the same region where your application is created. This bucket is required to store the contents of your application. This error is returned when this bucket cannot be created, in the following scenarios:

[13] An internal error occurred.

This error can occur if you are deploying your service with a network configuration using a Shared VPC setup. Ensure that your App Engine flexible environment fulfills all the requirements for this configuration. Next, make sure that the configured service accounts for this setup are present in your project, otherwise you will have to restore the accounts. Note that the region of the subnet in the Shared VPC host project, must match the location where your App Engine environment was created.

If the issue persists after ensuring your app.yaml configuration is valid, use the Google Cloud SDK to re-deploy your service, adding the --verbosity=debug flag, and contact GCP Support by providing the command's output.

IP space of {USER_SUBNETWORK_NAME} is exhausted and needs to be expanded.

If the deployment fails with this error message, it means that the network configured for the App Engine service doesn't have addresses left to allocate, for the new instances of the service. You can resolve the issue by expanding the VPC ranges on the subnet configured for your App Engine flexible environment service.