fix(proxy-mirror): keep the original method path when mirroring gRPC requests#13499
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…requests The grpc mirror location only has grpc_pass, which cannot carry a URI, so the mirrored request was sent with :path of the mirror subrequest URI /proxy_mirror_grpc. The gRPC mirror backend rejects such calls with UNIMPLEMENTED, making gRPC mirroring unusable. Capture the request path into the new $upstream_mirror_grpc_path variable in the before_proxy phase, which runs after access phase plugins (e.g. grpc-web) have rewritten the URI, and rewrite the mirror subrequest URI with it before grpc_pass. Fixes apache#13498
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Pull request overview
Fixes gRPC mirroring in the proxy-mirror plugin so mirrored gRPC subrequests preserve the effective method path (including URI rewrites performed by access-phase plugins like grpc-web), instead of incorrectly using the internal mirror location URI (/proxy_mirror_grpc).
Changes:
- Capture the final request URI in
before_proxyinto a new Nginx var ($upstream_mirror_grpc_path) for gRPC mirroring. - Rewrite the internal
/proxy_mirror_grpcsubrequest URI to$upstream_mirror_grpc_pathbeforegrpc_pass, so the mirrored:pathmatches the main upstream request. - Rework the gRPC mirror test to assert the mirrored request’s
:path,content-type, and body length (and add a grpc-web combined case).
Reviewed changes
Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
apisix/plugins/proxy-mirror.lua |
Adds before_proxy hook to capture the effective URI into $upstream_mirror_grpc_path when mirroring is enabled. |
apisix/cli/ngx_tpl.lua |
Declares $upstream_mirror_grpc_path and rewrites the gRPC mirror subrequest URI before grpc_pass. |
apisix/core/ctx.lua |
Registers upstream_mirror_grpc_path as a writable cached Nginx variable in ctx.var. |
t/APISIX.pm |
Updates test Nginx config template to declare and use $upstream_mirror_grpc_path for gRPC mirroring. |
t/plugin/proxy-mirror3.t |
Replaces the old “connection refused” gRPC mirror test with an h2c mirror server that validates mirrored request properties, plus a grpc-web case. |
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shreemaan-abhishek
approved these changes
Jun 10, 2026
AlinsRan
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Jun 10, 2026
membphis
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Jun 10, 2026
wistefan
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Jun 16, 2026
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Description
Fixes #13498
When
proxy-mirrormirrors to agrpc://host, the mirrored request was sent with:path = /proxy_mirror_grpc(the internal mirror location name) instead of the real gRPC method path, so the mirror backend rejects every call withUNIMPLEMENTED. The cause is thatgrpc_passcannot carry a URI (unlike the HTTP mirror location, which usesproxy_pass $upstream_mirror_uri), so the grpc module builds:pathfrom the mirror subrequest's own URI.The fix captures the request path into a new
$upstream_mirror_grpc_pathvariable and rewrites the mirror subrequest URI with it in theproxy_mirror_grpclocation beforegrpc_pass. The capture happens in thebefore_proxyphase rather than rewrite, because access phase plugins (e.g.grpc-web) may rewrite the URI afterproxy-mirror's rewrite phase has run;before_proxyruns after all of them, so the mirrored:pathalways matches what the main upstream receives.path/path_concat_modestay not applicable to gRPC mirroring, as already documented.The existing grpc mirror test from #9388 only asserted
Connection refusedagainst a closed port, so it could not catch this. It is reworked to mirror into a local h2c server that records the received request, asserting the:path,content-typeand body length of the mirrored request; a second case covers the combination withgrpc-web. Both fail before this fix (the mirror target receivespath=/proxy_mirror_grpc) and pass after.Checklist