Initial easyauth work

Signed-off-by: Alex Crome <afscrome@users.noreply.github.com>

docs/auth/microsoft/azure-easyauth.md

@@ -0,0 +1,120 @@
+---
+id: azure-easy-auth
+title: Azure EasyAuth Provider
+sidebar_label: Azure EasyAuth
+description: Adding Azure's EasyAuth Proxy as an authentication provider in Backstage
+---
+
+## Backstage Changes
+
+Add the following into your `app-config.yaml` or `app-config.production.yaml` file
+
+Add a `providerFactories` entry to the router in
+`packages/backend/src/plugins/auth.ts`.
+
+```ts
+import { providers } from '@backstage/plugin-auth-backend';
+
+export default async function createPlugin(
+  env: PluginEnvironment,
+): Promise<Router> {
+  const authProviderFactories = {
+    'azure-easyAuth': providers.easyAuth.create({
+      signIn: {
+        resolver: async (info, ctx) => {
+          const {
+            fullProfile: { id },
+          } = info.result;
+
+          if (!id) {
+            throw new Error('User profile contained no id');
+          }
+
+          return await ctx.signInWithCatalogUser({
+            annotations: {
+              'graph.microsoft.com/user-id': id,
+            },
+          });
+        },
+      },
+    }),
+  };
+
+  return await createRouter({
+    logger: env.logger,
+    config: env.config,
+    database: env.database,
+    discovery: env.discovery,
+    tokenManager: env.tokenManager,
+    providerFactories: authProviderFactories,
+  });
+}
+```
+
+Now the backend is ready to serve auth requests on the
+`/api/auth/azure-easyAuth/refresh` endpoint. All that's left is to update the frontend
+sign-in mechanism to poll that endpoint through the IAP, on the user's behalf.
+
+## Frontend Changes
+
+It is recommended to use the `ProxiedSignInPage` for this provider, which is
+installed in `packages/app/src/App.tsx` like this:
+
+```diff
++import { ProxiedSignInPage } from '@backstage/core-components';
+
+ const app = createApp({
+   components: {
++    SignInPage: props => <ProxiedSignInPage {...props} provider="azure-easyAuth" />,
+```
+
+See the [Sign-In with Proxy Providers](../index.md#sign-in-with-proxy-providers) section for more information.
+
+## Azure Configuration
+
+How to configure azure depends on the service you're enable AAD auth on the app service.
+
+### Azure App Services
+
+To use EasyAuth with App Services, turn on Active Directory authentication
+You must also enable the token store.
+
+The following example shows how to do this via a bicep template:
+
+```bicep
+resource webApp 'Microsoft.Web/sites@2022-03-01' existing = {
+  name: 'MY-WEBAPP-NAME'
+
+  resource authConfig 'config' = {
+    name: 'authsettingsV2'
+    properties: {
+      globalValidation: {
+        redirectToProvider: 'AzureActiveDirectory'
+        requireAuthentication: true
+        unauthenticatedClientAction: 'RedirectToLoginPage'
+      }
+      login: {
+        tokenStore: {
+          enabled: true
+        }
+      }
+      platform: {
+        enabled: true
+      }
+      identityProviders: {
+        azureActiveDirectory: {
+          enabled: true
+          login: {
+            loginParameters: [ 'domain_hint=MYCOMPANY.COM' ]
+          }
+          registration: {
+            clientId: 'CLIENT-ID'
+            clientSecretSettingName: 'CLIENT-SECRET-NAME'
+            openIdIssuer: 'https://sts.windows.net/${tenant().tenantId}/v2.0'
+          }
+        }
+      }
+    }
+  }
+}
+```