From dd89cd170e101b636c4fc6937a4f0a391f7af8f2 Mon Sep 17 00:00:00 2001
From: Filip Swiatczak <filip.swiatczak@gmail.com>
Date: Thu, 23 Sep 2021 18:20:18 +0100
Subject: [PATCH] Documentation added

Signed-off-by: Filip Swiatczak <filip.swiatczak@gmail.com>
---
 docs/auth/bitbucket/provider.md | 66 +++++++++++++++++++++++++++++++++
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 create mode 100644 docs/auth/bitbucket/provider.md

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+---
+id: provider
+title: GitHub Authentication Provider
+sidebar_label: GitHub
+description: Adding GitHub OAuth as an authentication provider in Backstage
+---
+
+The Backstage `core-api` package comes with a GitHub authentication provider
+that can authenticate users using GitHub or GitHub Enterprise OAuth.
+
+## Create an OAuth App on GitHub
+
+To add GitHub authentication, you must create either a GitHub App, or an OAuth
+App from the GitHub
+[developer settings](https://github.com/settings/developers). The `Homepage URL`
+should point to Backstage's frontend, while the `Authorization callback URL`
+will point to the auth backend.
+
+Note that if you're using a GitHub App, the allowed scopes are configured as
+part of that app. This means you need to verify what scopes the plugins you use
+require, so be sure to check the plugin READMEs for that information.
+
+Settings for local development:
+
+- Application name: Backstage (or your custom app name)
+- Homepage URL: `http://localhost:3000`
+- Authorization callback URL: `http://localhost:7000/api/auth/github`
+
+## Configuration
+
+The provider configuration can then be added to your `app-config.yaml` under the
+root `auth` configuration:
+
+```yaml
+auth:
+  environment: development
+  providers:
+    github:
+      development:
+        clientId: ${AUTH_GITHUB_CLIENT_ID}
+        clientSecret: ${AUTH_GITHUB_CLIENT_SECRET}
+        ## uncomment if using GitHub Enterprise
+        # enterpriseInstanceUrl: ${AUTH_GITHUB_ENTERPRISE_INSTANCE_URL}
+```
+
+The GitHub provider is a structure with three configuration keys:
+
+- `clientId`: The client ID that you generated on GitHub, e.g.
+  `b59241722e3c3b4816e2`
+- `clientSecret`: The client secret tied to the generated client ID.
+- `enterpriseInstanceUrl` (optional): The base URL for a GitHub Enterprise
+  instance, e.g. `https://ghe.<company>.com`. Only needed for GitHub Enterprise.
+
+## Adding the provider to the Backstage frontend
+
+To add the provider to the frontend, add the `githubAuthApi` reference and
+`SignInPage` component as shown in
+[Adding the provider to the sign-in page](../index.md#adding-the-provider-to-the-sign-in-page).
+
+## Difference between GitHub Apps and GitHub OAuth Apps
+
+GitHub Apps handle OAuth scope at the app installation level, meaning that the
+`scope` parameter for the call to `getAccessToken` in the frontend has no
+effect. When calling `getAccessToken` in open source plugins, one should still
+include the appropriate scope, but also document in the plugin README what
+scopes are required for GitHub Apps.