pomerium / pomerium / 22155682528

45%

Build Type

push

github

Committed by web-flow

Commit Message

mcp: pass upstream host via route context metadata and extend HostInfo (#6119)

## Summary

Establish the routing plumbing needed for ext_proc to know the actual
upstream hostname. Envoy rewrites `:authority` to the upstream host
*after* ext_proc processes request headers, so ext_proc must receive the
real upstream host via route context metadata from ext_authz.

- Add `FieldUpstreamHost` constant and pass upstream hostname from
ext_authz → ext_proc via route context metadata
- Extend `ServerHostInfo` with `UpstreamURL` (built from policy `To`
config) and `RouteID` fields for upstream discovery and token storage
keying
- Add tests for `UpstreamURL` construction with and without server paths

## Related issues

-
[ENG-3590](https://linear.app/pomerium/issue/ENG-3590/mcp-pass-upstream-host-metadata-to-ext-proc-and-extend-hostinfo)

## User Explanation

No user-facing changes. Internal routing metadata addition.

## Checklist

- [x] reference any related issues
- [x] updated unit tests
- [x] add appropriate label (`enhancement`, `bug`, `breaking`,
`dependencies`, `ci`)
- [ ] ready for review

Run Details

25 of 27 new or added lines in 3 files covered. (92.59%)

31 existing lines in 7 files now uncovered.

32640 of 73587 relevant lines covered (44.36%)

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