Deploying a Python App

Deploy your app to upload and run them on App Engine. When you deploy your apps, you create versions of those apps and their corresponding services in App Engine. You can deploy entire apps, including all the source code and configuration files, or you can deploy and update individual versions or configuration files.

Before you begin

You must download, install, and initialize the Google Cloud SDK , which includes the gcloud tool:

Download the SDK

If you already have the gcloud tool installed and want to configure it to use a Cloud Platform Console project ID other than the one that you initialized it to, see Managing Cloud SDK Configurations.

Using a proxy

If you are running the deployment command from a system which uses an HTTP or HTTPS proxy, you must configure the tool so that it can communicate via the proxy.


Run the following commands to configure the gcloud tool:

gcloud config set proxy/type [PROXY_TYPE]
gcloud config set proxy/address [PROXY_ADDRESS]
gcloud config set proxy/port [PROXY_PORT]

You can also set a username and password for the proxy. For more information, see gcloud config.


Set the environment variable that corresponds to your proxy:

Mac / Linux
export HTTP_PROXY=""
export HTTPS_PROXY=""

Deploying an app

To deploy your app to App Engine, you run the gcloud app deploy command from within the root directory of your application where your configuration files are located, for example app.yaml.


gcloud app deploy [YOUR_DEPLOYMENTS]

Where [YOUR_DEPLOYMENTS] is one or more configuration file's path and name. You separate each configuration file that you specify with a single white space. By default, the app.yaml is deployed when no configuration file is specified.

Optional flags:

  • Include the --project flag to specify an alternate Cloud Platform Console project ID to what you initialized as the default in the gcloud tool. Example: --project [YOUR_PROJECT_ID]
  • Include the -v flag to specify a version ID, otherwise one is generated for you. Example: -v [YOUR_VERSION_ID]


gcloud app deploy
gcloud app deploy app.yaml dos.yaml index.yaml
gcloud app deploy --project [YOUR_PROJECT_ID] -v [YOUR_VERSION_ID]

By default, each version that you deploy is automatically configured to receive 100% of traffic. For configuration options, see the --promote flag in the gcloud app deploy reference.

Tip: Run gcloud help from the command line for a complete list of arguments and flags.


By default, the initial version that you deploy to a service is automatically configured to receive 100% of traffic. However, all subsequent versions that you deploy to the same service must be manually configured, otherwise they receive no traffic.

Deploying multiple service applications

When your application is factored into multiple services, you can deploy and update individually targeted services or all the services simultaneously. Deploying updates to services can include updating individual configuration files or updating the source code in the corresponding versions.

For example, you can deploy and create two versions in App Engine, where each version runs in their own service. The first version serves as the frontend service and the other as the backend of your app. You can then deploy individual configuration files to update only the settings of a service. You can also choose to deploy a new version to a service in order to update the source code of the frontend, backend, or both simultaneously.

Requirements for multiple services

You use the same deployment commands for deploying and updating the multiple services of your application with the following requirements:

  • You must initially deploy a version of your app to the default service before you can create and deploy subsequent services.

  • You must specify the ID of your service in the app.yaml configuration file of the corresponding version. To specify the service ID, you include the service: [YOUR_SERVICE_ID] element definition in each configuration file. By default, excluding this element definition from your configuration file deploys the version to the default service.

  • You must specify all the corresponding app.yaml configuration files in your deployment command to simultaneously deploy multiple services.

To deploy multiple services

From the root directory of the application where the configuration files are located, you run the deployment command and specify the relative paths and file names for each service's app.yaml file:


gcloud app deploy [DEPLOYMENTS]

appcfg update [DEPLOYMENTS]

Where [DEPLOYMENTS] is one or more configuration file's path and name. You separate each configuration file that you specify with a single white space.



gcloud app deploy main/app.yaml service1/app.yaml service2/app.yaml

appcfg update main/app.yaml service1/app.yaml service2/app.yaml

You will receive verification via the command line as each service is successfully deployed.

Updating indexes

If your app's index.yaml file defines an index that doesn't yet exist, App Engine will create it after you upload your app.

It can take a while for App Engine to create all the indexes. If your app is already configured to receive traffic, any query that requires one of the missing indexes will raise an exception until that index is built.

To avoid exceptions you must allow time for the indexes to build, for example:


The following are common error messages that you might encounter:

Command not found

If you did not create symlinks for the or tools when you installed the SDK, you might need to specify the full directory path to run the tool, for example: [PATH_TO_APP_ENGINE_SDK]/ or [PATH_TO_CLOUD_SDK]/bin/

Note: To use you must download and install the App Engine SDK for Python.

[400] The first service (module) you upload to a new application must be the 'default' service (module)

Before you can deploy and create the multiple services of your application, you must first deploy and create the default service. For details about how to deploy a version to the default service, see Deploying multiple service applications.

Too Many Versions (403)

App Engine has a limit on the number of deployed versions of your application. These differ for free applications and deployed applications. You can use the Cloud Platform Console to delete an older version and then upload your latest code.

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App Engine standard environment for Python