[jlaneve]

A React plugin with destination: "base" renders on every page, but the UI learns its bundle URL only from GET /api/v2/plugins, after the UI's own scripts have run. On a Fast 3G profile the browser starts the bundle download 11.3 s into the page load, so the plugin shows up late and the page moves down. The server now adds a modulepreload link to index.html for each base app's bundle, and the browser starts the download 0.2 s into the load. The UI's later import() of the same URL takes the preloaded module, so the bundle still downloads once.

Only plugins without a team get a link. The server renders the page before it knows the user, so it can't apply the team filter that GET /api/v2/plugins applies. For the same reason, a user who can't view plugins still downloads a global base plugin's bundle, which the UI never imports.

I checked this on Airflow 3.3.1 in Chromium, Firefox and WebKit, with one base plugin and a base path. Every page load downloaded the bundle once, including a bundle on another origin. On Fast 3G the plugin appeared 0.8 s after the page instead of 1.3 s. On Fast 4G it made no difference.

Call-stack diff

  GET /{rest_of_path}                       core_api/app.py
  └─ webapp()
     └─ TemplateResponse("/index.html")
        ├─ backend_server_base_url          # unchanged
+       └─ preload_bundle_urls              # computed once in init_views
+          └─ base_react_app_bundle_urls()
+             └─ get_plugin_info(["react_apps"])  # base apps, no team

  index.html
     <base href>                            # unchanged
+    <link rel="modulepreload" href>        # one per base bundle

Unchanged: ReactPlugin still loads the bundle with import() and resolves the URL against document.baseURI. The <link> follows <base>, so both resolve to the same URL.

Related: #74762

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[github-actions]

Backport successfully created: v3-4-test

Note: As of Merging PRs targeted for Airflow 3.X
the committer who merges the PR is responsible for backporting the PRs that are bug fixes (generally speaking) to the maintenance branches.

In matter of doubt please ask in #release-management Slack channel.

Status	Branch	Result
✅	v3-4-test