.. _howto/auth/github:

===================================
Authenticate using GitHub Usernames
===================================

The **GitHub Authenticator** lets users log into your JupyterHub using their
GitHub user ID / password. To do so, you'll first need to register an
application with GitHub, and then provide information about this
application to your ``tljh`` configuration.

.. note::

   You'll need a GitHub account in order to complete these steps.

Step 1: Create a GitHub application
===================================

#. Go to the `GitHub OAuth app creation page <https://github.com/settings/applications/new>`_.

   * **Application name**: Choose a descriptive application name (e.g. ``tljh``)
   * **Homepage URL**: Use the IP address or URL of your JupyterHub. e.g. ``http(s)://<my-tljh-url>```.
   * **Application description**: Use any description that you like.
   * **Authorization callback URL**: Insert text with the following form::

          http(s)://<my-tljh-ip-address>/hub/oauth_callback

   * When you're done filling in the page, it should look something like this:

      .. image:: ../../images/auth/github/create_application.png
         :alt: Create a GitHub OAuth application
#. Click "Register application". You'll be taken to a page with the registered application details.
#. Copy the **Client ID** and **Client Secret** from the application details
   page. You will use these later to configure your JupyterHub authenticator.

   .. image:: ../../images/auth/github/client_id_secret.png
     :alt: Your client ID and secret

.. important::

   If you are using a virtual machine from a cloud provider and
   **stop the VM**, then when you re-start the VM, the provider will likely assign a **new public
   IP address** to it. In this case, **you must update your GitHub application information**
   with the new IP address.

Configure your JupyterHub to use the GitHub Oauthenticator
==========================================================

We'll use the ``tljh-config`` tool to configure your JupyterHub's authentication.
For more information on ``tljh-config``, see :ref:`topic/tljh-config`.

#. Log in as an administrator account to your JupyterHub.
#. Open a terminal window.

   .. image:: ../../images/notebook/new-terminal-button.png
      :alt: New terminal button.

#. Configure the GitHub OAuthenticator to use your client ID, client secret and callback URL with the following commands::

     sudo tljh-config set auth.GitHubOAuthenticator.client_id '<my-tljh-client-id>'

   ::

     sudo tljh-config set auth.GitHubOAuthenticator.client_secret '<my-tljh-client-secret>'
   
   ::

     sudo tljh-config set auth.GitHubOAuthenticator.oauth_callback_url 'http(s)://<my-tljh-ip-address>/hub/oauth_callback'

#. Tell your JupyterHub to *use* the GitHub OAuthenticator for authentication::

     sudo tljh-config set auth.type oauthenticator.github.GitHubOAuthenticator

#. Restart your JupyterHub so that new users see these changes::

     sudo tljh-config reload

Confirm that the new authentactor works
=======================================

#. **Open an incognito window** in your browser (do not log out until you confirm
   that the new authentication method works!)
#. Go to your JupyterHub URL.
#. You should see a GitHub login button like below:

   .. image:: ../../images/auth/github/login_button.png
      :alt: The GitHub authenticator login button.

#. After you log in with your GitHub credentials, you should be directed to the
   Jupyter interface used in this JupyterHub.

#. **If this does not work** you can revert back to the default
   JupyterHub authenticator by following the steps in :ref:`howto/auth/firstuse`.
