• Enable your Python Flask webapp to sign in users to your Azure Active Directory B2C tenant with the Microsoft identity platform
  • Overview
  • Scenario
  • Contents
  • Prerequisites
  • Setup
    • Step 1: Clone or download this repository
    • Step 2: Install project dependencies
    • Register the sample application with your Azure AD B2C tenant
    • Choose the Azure AD B2C tenant where you want to create your applications
    • Create User Flows and Custom Policies
    • Add External Identity Providers
    • Register the webapp (b2c-python-flask-webapp-auth)
  • Running the sample
  • Explore the sample
  • We'd love your feedback!
  • About the code
    • Under the hood
  • Deploy to Azure
  • More information
  • Community Help and Support
  • Contributing
  • Code of Conduct

This sample demonstrates a Python Flask webapp that authenticates users with Azure Active Directory B2C (Azure AD B2C) using the the Microsoft Authentication Library (MSAL) for Python.

1. The Web application uses MSAL for Python to sign-in a user and obtains an ID Token from Azure AD B2C.
2. The ID Token proves that the user has successfully authenticated against an Azure AD B2C tenant.
3. The web application protects one of its routes according to user's authentication status.
4. The user can sign up for a new account, reset password, or edit user profile information using B2C user-flows

• Python 3.8
• A virtual environment to install packages from requirements.txt
• An Azure AD B2C tenant. For more information see: How to get an Azure AD B2C tenant (optional)

From your shell or command line:

git clone https://github.com/Azure-Samples/ms-identity-b2c-python-flask-webapp-authentication.git

or download and extract the repository .zip file.

1. Navigate to the project folder
2. Activate a Python 3 virtual environment
3. Install project dependencies

• In Linux/OSX via the terminal:

  cd <project-root-directory> # the folder into which you cloned this project
  python3 -m venv venv # only required to create the venv if you don't have a venv already
  source venv/bin/activate # activates the venv
  pip install -r requirements.txt

• In Windows via PowerShell:

  cd <project-root-directory> # the folder into which you cloned this project
  python3 -m venv venv # only required to create the venv if you don't have a venv already
  Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope Process -Force
  . .\venv\Scripts\Activate.ps1 # activates the venv
  pip install -r requirements.txt

⚠️ This sample comes with a pre-registered application for testing purposes. If you would like to use your own Azure AD B2C tenant and application, follow the steps below to register and configure the application in the Azure Portal. Otherwise, continue with the steps for Running the sample.

• To run the sample, open a terminal window. Navigate to the root of the project. Be sure your virtual environment with dependencies is activated (Prerequisites).

• On Linux/OSX via the terminal:

    export FLASK_APP=app.py
    export FLASK_ENV=development
    export FLASK_DEBUG=1
    export FLASK_RUN_CERT=adhoc
    flask run

• On Windows:

    $env:FLASK_APP="app.py"
    $env:FLASK_ENV="development"
    $env:FLASK_DEBUG="1"
    $env:FLASK_RUN_CERT="adhoc"
    flask run

• Alternatively, you may use python -m flask run instead of flask run

• Navigate to https://127.0.0.1:5000 in your browser

You might run into an invalid certificate error on your browser as we are using self-signed certificates for https. If you do, you can ignore that error while running this sample locally.

• Note the signed-in or signed-out status displayed at the center of the screen.
• Click the context-sensitive button at the top right (it will read Sign In on first run)
• Follow the instructions on the next page to sign in with an account of your chosen identity provider.
• Note the context-sensitive button now says Sign out and displays your username to its left.
• The middle of the screen now has an option to click for ID Token Details: click it to see some of the ID token's decoded claims.
• You also have the option of editing your profile. Click the link to edit details like your display name, place of residence, and profession.
• You can also use the button on the top right to sign out.
• After signing out, click the link to ID Token Details to observe how the app displays a 401: unauthorized error instead of the ID token claims.

ℹ️ Did the sample not work for you as expected? Did you encounter issues trying this sample? Then please reach out to us using the GitHub Issues page.

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This sample uses the Microsoft Authentication Library (MSAL) for Python to sign up and/or sign in users with an Azure AD B2C tenant. It leverages the IdentityWebPython class found in the Microsoft Identity Python Samples Common repository to allow for quick app setup.

In app.py's def create_app method:

1. A configuration object is parsed from aad.b2c.config.json

2. A FlaskAdapter is instantiated for interfacing with the Flask app

3. The FlaskAdapter and an Azure AD configuration object are used to instantiate IdentityWebPython.

   aad_configuration = AADConfig.parse_json('aad.b2c.config.json')
   adapter = FlaskContextAdapter(app)
   ms_identity_web = IdentityWebPython(aad_configuration, adapter)

• These three lines of code automatically hook up all necessary endpoints for the authentication process into your Flask app under a route prefix (/auth by default). For example, the redirect endpoint is found at /auth/redirect.

• When a user navigates to /auth/sign_in and completes a sign-in attempt, the resulting identity data is put into the session, which can be accessed through the flask global g object at g.identity_context_data.

• When an endpoint is decorated with @ms_identity_web.login_required, the application only allows requests to the endpoint from authenticated (signed-in) users. If the user is not signed-in, a 401: unauthorized error is thrown, and the browser is redirected to the 401 handler.

  @app.route('/a_protected_route')
  @ms_identity_web.login_required
  def a_protected_route():
    return "if you can see this, you're signed in!"

In this sample, much of the required MSAL for Python configurations are automatically setup using utilities found in Microsoft Identity Python Samples Common. For a more direct, hands-on demonstration of the sign-in process without this abstraction, please see the code within this Python Webapp sample.

At a minimum, following parameters need to be provided to the MSAL for Python library:

• The Client ID of the app
• The Client Credential, which is a requirement for Confidential Client Applications
• The Azure AD B2C Authority concatenated with an appropriate UserFlowPolicy for sign-up-sign-in or profile-edit or password-reset.

1. The first step of the sign-in process is to send a request to the /authorize endpoint on Azure Active Directory.

2. An MSAL for Python ConfidentialClientApplication instance is created by ms_identity_web, like so:

   client_instance = msal.ConfidentialClientApplication(
     client_id=CLIENT_ID,
     client_credential=CLIENT_CREDENTIAL,
     authority=f'{AUTHORITY}/{B2C_SIGN_UP_SIGN_IN_USER_FLOW_POLICY}',
   )

3. The client_instance instance is leveraged to construct a /authorize request URL with the appropriate parameters, and the browser is redirected to this URL.

4. The user is presented with a sign-in prompt by Azure Active Directory B2C. If the sign-in attempt is successful, the user's browser is redirected back to this app's /redirect endpoint. A successful request to this endpoint will contain an authorization code.

5. The client_instance is used to exchange this authorization code for an ID Token and Access Token from Azure Active Directory.

   token_acquisition_result = client_instance.acquire_token_by_authorization_code(authorization_code, SCOPES)
   # this sends the authorization code to Azure AD's `/token` endpoint to request a token.

6. If the request is successful, MSAL for Python validates the signature and nonce of the incoming token. If these checks succeed, it returns the resulting id_token, access_token and plaintext id_token_claims in a dictionary. It is the application's responsibility to store these tokens securely.

Follow this guide to deploy this app to Azure App Service.

• Microsoft Authentication Library (MSAL) for Python
• MSAL Python ReadTheDocs
• What is Azure Active Directory B2C?
• Application types that can be used in Active Directory B2C
• Recommendations and best practices for Azure Active Directory B2C
• Azure AD B2C session
• MSAL code samples

Use Stack Overflow to get support from the community. Ask your questions on Stack Overflow first and browse existing issues to see if someone has asked your question before. Make sure that your questions or comments are tagged with [azure-active-directory ms-identity adal msal].

If you find a bug in the sample, please raise the issue on GitHub Issues.

To provide a recommendation, visit the following User Voice page.

This project welcomes contributions and suggestions. Most contributions require you to agree to a Contributor License Agreement (CLA) declaring that you have the right to, and actually do, grant us the rights to use your contribution. For details, visit https://cla.opensource.microsoft.com.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact [email protected] with any additional questions or comments.