[Feat]: add test suite for running e2e tests behind proxy/not root

[jsjoeio]

What is your suggestion?

To modify our e2e test setup to run the same tests but in an environment that runs code-server not on the root path i.e. behind /ide or something.

Why do you want this feature?

It mimics how many of our users run code-server and also mimics how we run code-server in both Coder and Coder OSS.

It would have prevented a high-impact bug we accidentally introduced in 4.5.0.

See #5321

Are there any workarounds to get this functionality today?

Manually testing code-server behind a reverse proxy with Caddy before each release 😅

Are you interested in submitting a PR for this?

Yes

Notes

Instead of duplicating tests, it would be cool if we added a new script like yarn test:e2e:caddy or something which spun up Caddy in front of code-server and then ran the tests using that environment.

Currently the e2e tests run in parallel (I believe) and use random ports so we'd have to use a wildcard in Caddy (I'm pretty sure it can do that).

We'd also have to make sure code-server's address had the path in it. I'm guessing we could do some environment variable logic or something like PATH_TO_USE="/ide" and then dynamically set address.

_notes from Discord call with @code-asher _

• install Caddy
• launch Caddy
• set env variable to use proxy or special path

we might be able to use named matchers.

simplest way to do this:

• write Caddyfile
• run code-server on one port and make sure it works as expected
• run it on another port and make sure it works

:80 {
        @portLocalhost header_regexp port Host ^([0-9]+)\.localhost$
        handle @portLocalhost {
                reverse_proxy localhost:{re.port.1}
        }
        
        handle {        
                respond "Bad hostname" 400
        }
}

USE_PROXY=1

caddy start

if(USE_PROXY && USE_PROXY=1) {
  return port.localhost
}

const uri = new URL(address)
const port = uri.port

• add support for USE_PROXY
• add Caddyfile