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Integrate into the Service Catalog

This is an advanced use case and currently is an experimental feature. Expect API to change over time

Steps

1. Create a plugin
2. Export a router with relative routes
3. Import and use router in the APP

Create a plugin

Follow the same process as for standalone plugin. You should have a separate package in a folder, which represents your plugin.

Example:

$ yarn create-plugin
> ? Enter an ID for the plugin [required] my-plugin
> ? Enter the owner(s) of the plugin. If specified, this will be added to CODEOWNERS for the plugin path. [optional]

Creating the plugin...

Export a router

Now in the plugin you have a Router.tsx file in the src folder. By default it contains only one example route. Create a routing structure needed for your plugin, keeping in mind that the whole set of routes defined here are going to be mounted under some different route in the App.

Example:

my-plugin consists of 2 different views - /me and /about. I envision people integrating it into plugin catalog as a tab named "MyPlugin". Then, my Routes.tsx for the plugin is going to look like:

<Routes>
  <Route path="/me" element={<MePage />} />
  <Route path="/about" element={<AboutPage />} />
</Routes>

(where MePage and AboutPage are 2 components defined in your plugin and imported accordingly inside Router.tsx)

Pay attention, if your MePage references the AboutPage it needs to do it through link to about, not /about. This allows react-router v6 to enable its relative routing mechanism. Read more - https://reacttraining.com/blog/react-router-v6-pre/#relative-route-path-and-link-to

Import and use router in the APP

In the app/src/components/catalog/EntityPage.tsx (app === your folder, containing backstage app) import your created Router:

import { Router as MyPluginRouter } from '@backstage/plugin-my-plugin;

Now, you need to mount MyPluginRouter onto some route, for example if you had:

const DefaultEntityPage = ({ entity }: { entity: Entity }) => (
  <EntityPageLayout>
    <EntityPageLayout.Content
      path="/"
      title="Overview"
      element={<OverviewPage entity={entity} />}
    />
  </EntityPageLayout>
);

after you add your code it becomes:

const DefaultEntityPage = ({ entity }: { entity: Entity }) => (
  <EntityPageLayout>
    <EntityPageLayout.Content
      path="/"
      title="Overview"
      element={<OverviewPage entity={entity} />}
    />
    <EntityPageLayout.Content
      path="/my-plugin"
      title="My Plugin"
      element={<MyPluginRouter entity={entity} />}
    />
  </EntityPageLayout>
);

All of magic happens thanks to the EntityPageLayout component, which comes as an export from @backstage/plugin-catalog package.

type EntityPageLayoutContentProps = {
  /**
   * Going to be transformed into react-router v6
   * path under the hood. Read more at https://reacttraining.com/blog/react-router-v6-pre
   */
  path: string;
  /**
   * Gets transformed into the title for the tab
   */
  title: string;
  /**
   * Element that is rendered when the location
   * matches the path provided
   */
  element: JSX.Element;
};

You can either pass the entity from App to the plugin's router as a prop or use useEntity hook from @backstage/plugin-catalog directly inside your plugin.