Create a Python app in the App Engine flexible environment

Region ID

TheREGION_ID is an abbreviated code that Google assignsbased on the region you select when you create your app. The code does notcorrespond to a country or province, even though some region IDs may appearsimilar 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 moreabout region IDs.

Note: If you are deploying a new Python web service to Google Cloud,we recommend getting started withCloud Run.

This quickstart demonstrates how to create and deploy an app that displays ashort message. You canuse the sample application in this quickstart for anysupported version of Python, by specifying the runtime version and operating system in yourapp.yaml file.

Before you begin

  1. Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.

  2. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

    Roles required to select or create a project

    • Select a project: Selecting a project doesn't require a specific IAM role—you can select any project that you've been granted a role on.
    • Create a project: To create a project, you need the Project Creator role (roles/resourcemanager.projectCreator), which contains theresourcemanager.projects.create permission.Learn how to grant roles.
    Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

    Go to project selector

  3. Verify that billing is enabled for your Google Cloud project.

  4. Enable the Cloud Build API.

    Roles required to enable APIs

    To enable APIs, you need the Service Usage Admin IAM role (roles/serviceusage.serviceUsageAdmin), which contains theserviceusage.services.enable permission.Learn how to grant roles.

    Enable the API

  5. Install the Google Cloud CLI.

  6. If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

  7. Toinitialize the gcloud CLI, run the following command:

    gcloudinit

  8. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

    Roles required to select or create a project

    • Select a project: Selecting a project doesn't require a specific IAM role—you can select any project that you've been granted a role on.
    • Create a project: To create a project, you need the Project Creator role (roles/resourcemanager.projectCreator), which contains theresourcemanager.projects.create permission.Learn how to grant roles.
    Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

    Go to project selector

  9. Verify that billing is enabled for your Google Cloud project.

  10. Enable the Cloud Build API.

    Roles required to enable APIs

    To enable APIs, you need the Service Usage Admin IAM role (roles/serviceusage.serviceUsageAdmin), which contains theserviceusage.services.enable permission.Learn how to grant roles.

    Enable the API

  11. Install the Google Cloud CLI.

  12. If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

  13. Toinitialize the gcloud CLI, run the following command:

    gcloudinit

Required roles

To get the permissions that you need to complete this quickstart, ask your administrator to grant you the following IAM roles:

For more information about granting roles, seeManage access to projects, folders, and organizations.

You might also be able to get the required permissions throughcustom roles or otherpredefined roles.

Additional prerequisites

  1. Initialize your App Engine app with your project and choose its region:

    gcloudappcreate--project=[YOUR_PROJECT_ID]

    When prompted, select theregionwhere you want to locate your App Engine application.

    Caution: You cannot change an app's regiononce it has been set.

  2. Install the following on your local machine:

    • Run the following command to install thegcloud component that includes theApp Engine extension for Python:

      gcloudcomponentsinstallapp-engine-python

  3. Prepare your environment for Python development. It is recommended that youhave the latest version of Python,pip, and other related toolsinstalled on your system. For instructions, refer to thePython Development Environment Setup Guide.

App Engine locations

App Engine isregional, which means the infrastructure that runs your apps islocated in a specific region, and Google manages it so that it is availableredundantly acrossall of the zones within that region.

Meeting your latency, availability, or durability requirements are primaryfactors for selecting the region where your apps are run. You can generallyselect the region nearest to your app's users, but you should considerthelocations where App Engine is availableas well as thelocations of the otherGoogle Cloud products and services that your app uses. Using servicesacross multiple locations can affect your app's latency as well as itspricing.

You cannot change an app's region after you set it.

Note: Two locations, which are calledeurope-west andus-central in App Engine commands and in the Google Cloud console,are calledeurope-west1 andus-central1, respectively,elsewhere in Google documentation.

If you already created an App Engine application, you can view itsregion by doing one of the following:

This quickstart demonstrates the latest Python 3 app written with theFlask web framework that can be deployed to App Engine. Although this sampleuses Flask, you can use any web framework that satisfies the requirements above.Alternative frameworks includeDjango,Pyramid,Bottle, andweb.py.

Download the Hello World app

We've created a Hello World app for App Engine so you can quicklyget a feel for deploying an app to the Google Cloud.

  1. Clone the Hello World sample app repository to your local machine.

    gitclonehttps://github.com/GoogleCloudPlatform/python-docs-samples

    Alternatively, you candownload the sample as a zip file and extract it.

  2. Change to the directory that contains the sample code.

    cdpython-docs-samples/appengine/flexible/hello_world

Run Hello World on your local machine

To run the Hello World app on your local computer:

Mac OS / Linux

Note: These instructions describe how to set up a virtual environment in Python 3. For Python 2apps, usevirtualenv to set up a virtual environment.
  1. Create anisolated Python environment:
    python3-mvenvenvsourceenv/bin/activate
  2. If you're not in the directory that contains the sample code, navigate to the directory that contains thehello_world sample code. Then install dependencies:
    cdYOUR_SAMPLE_CODE_DIRpipinstall-rrequirements.txt
  3. Run the application:
    pythonmain.py
  4. In your web browser, enter the following address:
    http://localhost:8080

    If you are using Cloud Shell, in the toolbar, clickWeb Preview and selectPreview on port 8080 instead.

Windows

Note: These instructions describe how to set up a virtual environment in Python 3. For Python 2apps, usevirtualenv to set up a virtual environment.

Use PowerShell to run your Python packages.

  1. Locate your installation ofPowerShell.
  2. Right-click on the shortcut to PowerShell and start it as an administrator.
  3. Create anisolated Python environment.
    python-mvenvenv.\env\Scripts\activate
  4. Navigate to your project directory and install dependencies. If you're not in the directory that contains the sample code, navigate to the directory that contains thehello_world sample code. Then, install dependencies:
    cdYOUR_SAMPLE_CODE_DIRpipinstall-rrequirements.txt
  5. Run the application:
    pythonmain.py
  6. In your web browser, enter the following address:
    http://localhost:8080

TheHello World message from the sample app displays on the page. In yourterminal window, pressCtrl+C to exit the web server.

Deploy and run Hello World on App Engine

To deploy your app to the App Engine flexible environment:

  1. Deploy the Hello World app by running the following command from thehello_world directory:

    gcloudappdeploy

    Learn about the optional flags.

    Commongcloud command flags

    • Include the--version flag to specify an ID that uniquely identifies that version of your app, otherwise one is generated for you. Example:--version [YOUR_VERSION_ID]
    • Include the--project flag to specify an alternate Google Cloud project ID to what you initialized as the default in thegcloud tool. Example:--project [YOUR_PROJECT_ID]

    Example:

    gcloud app deploy --version pre-prod-5 --project my-sample-app

    To learn more about deploying your app from the command line, seeTesting and Deploying Your App. For a list of all the command flags, see thegcloud app deployreference.

  2. Launch your browser to view the app athttps://PROJECT_ID.REGION_ID.r.appspot.com

    gcloudappbrowse
     wherePROJECT_ID represents your Google Cloud project ID.

This time, the page that displays the Hello World message is delivered by aweb server running on an App Engine instance.

Congratulations! You've deployed your first App Engine app to theApp Engine flexible environment!

If you encountered any errors deploying your application, check thetroubleshooting tips.

See the following sections for information about cleaning up as well as links topossible next steps that you can take.

Clean up

To avoid incurring charges, you can delete your Google Cloud project to stopbilling for all the resources used within that project.

    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 anappspot.com URL, delete selected resources inside the project instead of deleting the whole project.
  1. In the Google Cloud console, go to theManage resources page.

    Go to Manage resources

  2. In the project list, select the project that you want to delete, and then clickDelete.
  3. In the dialog, type the project ID, and then clickShut down to delete the project.

What's next

Learn the whole platform

Now that you know what it's like to develop and deploy App Engine apps,you can explore the rest of Google Cloud. You already have theGoogle Cloud CLI installed which gives you the tools to interact withproducts like Cloud SQL, Cloud Storage, Firestore,and more.

Learn about the App Engine flexible environment

Here are some topics to help continue your learning about App Engine:

Hello World code review

Hello World is the simplest possible App Engine app, as it contains onlyone service, has only one version, and all of the code is located within theapp's root directory. This section describes each of the app files in detail.

main.py

The Hello World app is a basic one-file Flask app.

fromflaskimportFlaskapp=Flask(__name__)@app.route("/")defhello()->str:"""Return a friendly HTTP greeting.    Returns:        A string with the words 'Hello World!'.    """return"Hello World!"if__name__=="__main__":# This is used when running locally only. When deploying to Google App# Engine, a webserver process such as Gunicorn will serve the app.app.run(host="127.0.0.1",port=8080,debug=True)

app.yaml

Theapp.yamlfile describes the following configuration for your app:

  • Setsenv: flex, indicating your app uses theApp Engine flexible environment.

  • Specifies the runtime used by the app. If you exclude theruntime_version setting, App Engine uses the latest Python version as the default version for your app.

  • Theentrypoint tells App Engine how to start the app. This app usesgunicorn to servethe Python app as an alternative to Flask'sdevelopment server (used when running locally). The$PORT variable is set by App Engine when it startsthe app. For more information aboutentrypoint, seeAppstartup.

Note: This is the simplest way to get gunicorn running. However this approachruns the application with a single blocking worker, which means all HTTP requestsare handled in serial, including health checks. In practice, this results inthe application becoming unresponsive in the event of slow requests. For moredetails on how to configure gunicorn for production, seeRecommended gunicorn configuration
# Copyright 2021 Google LLC## Licensed under the Apache License, Version 2.0 (the "License");# you may not use this file except in compliance with the License.# You may obtain a copy of the License at##      http://www.apache.org/licenses/LICENSE-2.0## Unless required by applicable law or agreed to in writing, software# distributed under the License is distributed on an "AS IS" BASIS,# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.# See the License for the specific language governing permissions and# limitations under the License.runtime:pythonenv:flexentrypoint:gunicorn -b :$PORT main:appruntime_config:operating_system:ubuntu22# This sample incurs costs to run on the App Engine flexible environment.# The settings below are to reduce costs during testing and are not appropriate# for production use. For more information, see:# https://cloud.google.com/appengine/docs/flexible/python/configuring-your-app-with-app-yamlmanual_scaling:instances:1resources:cpu:1memory_gb:0.5disk_size_gb:10

requirements.txt

requirements.txt and the Python package managerpip declare and install application dependencies. Hello World requiresFlask, a web framework, andGunicorn, a WSGI server.

Flask==3.0.3; python_version > '3.6'Flask==2.3.3; python_version < '3.7'Werkzeug==3.0.3; python_version > '3.6'Werkzeug==2.3.8; python_version < '3.7'gunicorn==23.0.0

requirements.txt defines the libraries that will be installed both locallyand when deploying to App Engine.

Except as otherwise noted, the content of this page is licensed under theCreative Commons Attribution 4.0 License, and code samples are licensed under theApache 2.0 License. For details, see theGoogle Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.

Last updated 2025-12-15 UTC.