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

Before you can deploy your app, you must have a Cloud Platform project and an App Engine application, see Managing Projects, Applications, and Billing for more information.

To deploy your app with the gcloud tool, you must download, install, and initialize the Google Cloud SDK:

Download the SDK

If you already have the gcloud tool installed and want to configure it to use a Cloud Platform 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.

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

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]

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

appcfg.py update [YOUR_APP_DIR] -A [YOUR_PROJECT_ID] -V [YOUR_VERSION_ID]

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.py 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.

Example

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

appcfg.py 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:

• You can deploy the new version of your app with a different version ID:

  1. Define a different version ID in your app's app.yaml file.
  2. Deploy the new version.
  3. In the Cloud Platform Console, monitor the status of the app's indexes.
  4. After the index has been built, move traffic over to the new version.

• You can deploy the index.yaml configuration file before you deploy the new version of your app:

  1. Deploy the index.yaml file:

     gcloud

     gcloud app deploy index.yaml

     appcfg

     appcfg.py update_indexes [YOUR_APP_DIR] -A [YOUR_PROJECT_ID] -V [YOUR_VERSION_ID]

  2. In the Cloud Platform Console, monitor the status of the app's indexes.

  3. After the index has been built, deploy the new version of your app.

Troubleshooting

The following are common error messages that you might encounter:

Command not found

If you did not create symlinks for the appcfg.py or dev_appserver.py 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]/appcfg.py or [PATH_TO_CLOUD_SDK]/bin/dev_appserver.py.

Note: To use appcfg.py 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.

What's next

• Learn how to download source code you've uploaded.
• Use services to build a large application.
• Split traffic or migrate traffic to route traffic to the versions you deploy.
• Review the gcloud app deploy command line arguments and flags.
• Optional: Review the appcfg command line arguments.