Add support for path prefix routing using "X-Forwarded-Prefix" header

[dain]

Description

This change allows the server to support routing with a path prefix,
enabling better compatibility with reverse proxies and load balancers
that use the "X-Forwarded-Prefix" header.

This feature is only enabled when http-server.process-forwarded is
true

NOTE: this does not add support to any of the client implementations, and may not work with any existing clients.

Additional context and related issues

Release notes

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# General
* Add suppot for processing `X-Forwarded-Prefix` header when `http-server.process-forwarded` is enabled. ({issue}`issuenumber`)

[dain]

Note there are no tests for this. I have no idea how we would test this. I also don't know if any Trino clients support this.

[losipiuk]

NOTE: this does not add support to any of the client implementations, and may not work with any existing clients.

What do we need it for then?

[dain]

@losipiuk I was thinking about this this morning, and I think we can do unit tests to verify the correct URL creation. There are 3 areas that I know are affected by this change on the server:

• Client protocol itself - TestQueryResource could have a test that verifies the url are as expected
• UI - TestWebUi and TestServer cover x-forwarded already, so we just need to extend this
• Oauth - Not sure exactally, but there are a number of OauthUI tests
  As the clients are updated (likely a separate PR), we would want tests that cover these. To make life eaier we could have a testing servelet filter that pretends to be a reverse proxy and modifies the stuff in the HTTP servelet request. It isn't hard but is really annoying as the Servlet APIs are hard to work with.

[findepi]

Does this add support for hosting Trino as eg http://localhost:8080/my-trino (with request going thru a proxy and path rewrite)?

[wendigo]

@findepi yes. That's how I understand this header as well

[github-actions]

This pull request has gone a while without any activity. Tagging the Trino developer relations team: @bitsondatadev @colebow @mosabua

[mosabua]

Would be great to get this merged and also ideally add some documentation...

[dain]

@mosabua I'm not sure if we want to promote this until the clients support it.

[mosabua]

@mosabua I'm not sure if we want to promote this until the clients support it.

Hm .. does it not work with clients at all or only in the edge case where catalog and schema are specified in the URL .. I kinda think we should document anyway and just say what does and doesnt work