Render swagger-ui on root endpoint in rest api

[mpetrunic]

It would be nice instead of 404 to render swagger-ui on http://localhost: to load swagger-ui with our server as primary server url.

Until we release spec, we should probably bundle spec into single file and ship it along.
There is some fastify plugin for that probably

[dapplion]

Do you want to bundle up with the beacon chain code the swagger UI, or add it to our CI pipeline publicly like https://api.prylabs.network/ ?

[mpetrunic]

I think it would be useful to bundle it. cc @wemeetagain

[wemeetagain]

My preference is to not bundle it, or somehow only optionally bundle it for debugging.
This is likewise to not bundling graphiql during production, but using it during development/debugging scenarios.

[dapplion]

Other clients don't bundle it up. Should this still be pursued? If we follow https://github.com/ethereum/eth2.0-APIs strictly is it necessary to maintain our own swagger UI?

[mpetrunic]

As I compromise, we could add redirect from lodestar api base url to https://github.com/ethereum/eth2.0-APIs .

It would be REALLY nice if we could pass server url somehow. That said, we are missing /eth prefix on all routes
for https://github.com/ethereum/eth2.0-APIs to be effective

[wemeetagain]

Would like this feature behind a CLI flag.

[wemeetagain]

Resolved with #5970