1. Tutorial setup

info

This documentation is written for the old backend which has been replaced by the new backend system, being the default since Backstage version 1.24. If have migrated to the new backend system, you may want to read its own article instead. Otherwise, consider migrating!

The following tutorial is designed to help plugin authors add support for permissions to their plugins. We'll add support for permissions to example todo-list and todo-list-backend plugins, but the process should be similar for other plugins!

The rest of this page is focused on adding the todo-list and todo-list-backend plugins to your Backstage instance. If you want to add support for permissions to your own plugin instead, feel free to skip to the next section.

Setup for the Tutorial

We will use a "Todo list" feature, composed of the todo-list and todo-list-backend plugins, as well as their dependency, todo-list-common.

The source code is available here:

• todo-list
• todo-list-backend
• todo-list-common

1. Copy-paste the three folders into the plugins folder of your backstage application repository (removing the example- prefix from each folder) or run the following script from the root of your backstage application:

   $ cd $(mktemp -d)
     git clone --depth 1 --quiet --no-checkout --filter=blob:none https://github.com/backstage/backstage.git .
     git checkout master -- plugins/example-todo-list/
     git checkout master -- plugins/example-todo-list-backend/
     git checkout master -- plugins/example-todo-list-common/
     sed -i '' 's/workspace:\^/\*/g' plugins/example-todo-list/package.json
     sed -i '' 's/workspace:\^/\*/g' plugins/example-todo-list-backend/package.json
     sed -i '' 's/workspace:\^/\*/g' plugins/example-todo-list-common/package.json
     for file in plugins/*; do mv "$file" "$OLDPWD/${file/example-todo/todo}"; done
     cd -

   The plugins directory of your project should now include todo-list, todo-list-backend, and todo-list-common.

   Important: if you are on Windows, make sure you have WSL and git installed on your machine before executing the script above.

2. Add these packages as dependencies for your Backstage app:

   From your Backstage root directory

   yarn --cwd packages/backend add @internal/plugin-todo-list-backend @internal/plugin-todo-list-common
   yarn --cwd packages/app add @internal/plugin-todo-list

3. Include the backend and frontend plugin in your application:

   Create a new packages/backend/src/plugins/todolist.ts with the following content:

   packages/backend/src/plugins/todolist.ts

   import { DefaultIdentityClient } from '@backstage/plugin-auth-node';
   import { createRouter } from '@internal/plugin-todo-list-backend';
   import { Router } from 'express';
   import { PluginEnvironment } from '../types';
   
   export default async function createPlugin({
     logger,
     discovery,
   }: PluginEnvironment): Promise<Router> {
     return await createRouter({
       logger,
       identity: DefaultIdentityClient.create({
         discovery,
         issuer: await discovery.getExternalBaseUrl('auth'),
       }),
     });
   }

   Apply the following changes to packages/backend/src/index.ts:

   packages/backend/src/index.ts

   import techdocs from './plugins/techdocs';
   import todoList from './plugins/todolist';
   import search from './plugins/search';
   
   async function main() {
     const searchEnv = useHotMemoize(module, () => createEnv('search'));
     const appEnv = useHotMemoize(module, () => createEnv('app'));
     const todoListEnv = useHotMemoize(module, () => createEnv('todolist'));
     // ..
   
     apiRouter.use('/proxy', await proxy(proxyEnv));
     apiRouter.use('/search', await search(searchEnv));
     apiRouter.use('/permission', await permission(permissionEnv));
     apiRouter.use('/todolist', await todoList(todoListEnv));
     // Add backends ABOVE this line; this 404 handler is the catch-all fallback
     apiRouter.use(notFoundHandler());
     // ..
   }

   Apply the following changes to packages/app/src/App.tsx:

   packages/app/src/App.tsx

   import { TodoListPage } from '@internal/plugin-todo-list';
   
   const routes = (
     <FlatRoutes>
       <Route path="/search" element={<SearchPage />}>
         {searchPage}
       </Route>
       <Route path="/settings" element={<UserSettingsPage />} />
       <Route path="/todo-list" element={<TodoListPage />} />
       {/* ... */}
     </FlatRoutes>
   );

Now if you start your application you should be able to reach the /todo-list page:

---

Integrate the new plugin

If you play with the UI, you will notice that it is possible to perform a few actions:

• create a new todo item (POST /todos)
• view todo items (GET /todos)
• edit an existing todo item (PUT /todos)

Let's try to bring authorization on top of each one of them.