Plugins: Support for link extensions

[mckn]

What is this feature?
This PR introduces an extensions registry that allows app plugins to extend core/plugins via plugin.json. It exposes a helper function for plugins/core to query the registry for extensions made by plugins allowing cross-plugin linking.

Links will only be registered if the app plugin defining the link:

• Is installed.
• Is enabled.
• Defines the link that we try to generate.

Why do we need this feature?
Please read the epic for more details.

Who is this feature for?
Plugin developers, Grafana developers and end-users.

Example

Here is an example on how to extend Grafana with a link from a plugin. It will place a link in Grafana (grafana/sandbox/testing):

{
  "$schema": "https://raw.githubusercontent.com/grafana/grafana/b56bc15bf5129d6d7590a5e4dce9023a826c26a2/docs/sources/developers/plugins/plugin.schema.json",
  "type": "app",
  "name": "Basic App",
  "id": "myorg-app-basic",
  "info": {
    "keywords": ["basic", "app", "example"],
    "description": "A basic grafana app plugin",
    "author": {
      "name": "Your name"
    },
    "logos": {
      "small": "img/logo.svg",
      "large": "img/logo.svg"
    },
    "screenshots": [],
    "version": "%VERSION%",
    "updated": "%TODAY%"
  },
  "includes": [
    {
      "type": "page",
      "name": "Page One",
      "path": "/a/%PLUGIN_ID%/one",
      "role": "Admin",
      "addToNav": true,
      "defaultNav": true
    },
    {
      "type": "page",
      "name": "Page Two",
      "path": "/a/%PLUGIN_ID%/two",
      "role": "Admin",
      "addToNav": true,
      "defaultNav": false
    },
    {
      "type": "page",
      "name": "Page Three",
      "path": "/a/%PLUGIN_ID%/three",
      "role": "Admin",
      "addToNav": true,
      "defaultNav": false
    },
    {
      "type": "page",
      "name": "Page Four",
      "path": "/a/%PLUGIN_ID%/four",
      "role": "Admin",
      "addToNav": true,
      "defaultNav": false
    },
    {
      "type": "page",
      "icon": "cog",
      "name": "Configuration",
      "path": "/plugins/%PLUGIN_ID%",
      "role": "Admin",
      "addToNav": true
    }
  ],
  "extensions": [
    {
      "target": "grafana/sandbox/testing",
      "title": "Open thing",
      "path": "/one",
      "type": "link"
    }
  ],
  "dependencies": {
    "grafanaDependency": ">=9.1.2",
    "plugins": []
  }
}

grafana/public/app/features/sandbox/TestStuffPage.tsx

Line 152 in b56bc15

const { extensions, error } = getPluginExtensions({ target });

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⚠️   Possible breaking changes

(Open the links below in a new tab to go to the correct steps)

grafana-data has possible breaking changes (more info)grafana-runtime has possible breaking changes (more info)

Console output Read our guideline

This is due to removal of the preload plugins types. It got replaced by the AppConfig types and should not have been used by plugin authors.

Resolved in discussions

[sdboyer]

my concerns are resolved, so i'm getting my review out of the way!

[DanCech]

Very cool!

The term "target" did throw me off initially since in html a link target refers to the name of the window the link should open in, whereas we're using it to mean the location that the link should be displayed.