🚀 Feature: new frontend system legacy plugin converter

[marleypowell]

🔖 Feature description

The @backstage/core-compat-api package seems to exist to provide compatibility for the new frontend system. It seems like the bridge for existing plugins is missing. This may have been intentional but it seems possible?

🎤 Context

This would allow existing plugins to be used with the new frontend system.

✌️ Possible Implementation

function convertLegacyPlugin(plugin: BackstagePlugin) {
  return createPlugin({
    id: plugin.getId(),
    extensions: Array.from(plugin.getApis()).map(factory =>
      createApiExtension({
        factory,
      }),
    ),
    routes: convertLegacyRouteRefs(plugin.routes),
    externalRoutes: convertLegacyRouteRefs(plugin.externalRoutes),
    featureFlags: Array.from(plugin.getFeatureFlags()),
  });
}

const app = createApp({
  features: [
    ...legacyFeatures,
    convertLegacyPlugin(catalogUnprocessedEntitiesPlugin)
  ],
});

👀 Have you spent some time to check if this feature request has been raised before?

• I checked and didn't find similar issue

🏢 Have you read the Code of Conduct?

• I have read the Code of Conduct

Are you willing to submit PR?

Yes I am willing to submit a PR!

[Rugvip]

Yep we'll likely look at adding this! 👍

The tricky bit are the extensions being provided through plugin.provide(...) in the old system, and how to handle those.