fix(query-frontend): restore trace ID in slow query logs#8762
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GiedriusS merged 3 commits intoMay 31, 2026
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PR thanos-io#8618 moved slow query logging into a defer and switched from using w.Header() (ResponseWriter headers) to resp.Header (round-trip response headers). The X-Thanos-Trace-Id header is set on w.Header() by the tracing middleware before the handler runs, so it was never present in resp.Header, causing trace IDs to be missing from slow query logs. Pass w.Header() to reportQueryStatsAndSlowQueries instead of the response object so the trace ID is available on both success and error paths. Fixes: thanos-io#8760 Signed-off-by: Pavel Litvyak <[email protected]>
Signed-off-by: Pavel Litvyak <[email protected]>
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lgtm |
GiedriusS
previously approved these changes
May 31, 2026
Signed-off-by: Giedrius Statkevičius <[email protected]>
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Changes
PR #8618 moved slow query logging into a defer and switched from using
w.Header()(ResponseWriter headers) toresp.Header(round-trip response headers). The X-Thanos-Trace-Id header is set onw.Header()by the tracing middleware before the handler runs, so it was never present in resp.Header, causing trace IDs to be missing from slow query logs.Pass
w.Header()toreportQueryStatsAndSlowQueriesinstead of the response object so the trace ID is available on both success and error paths.Fixes: #8760
Verification
Added an additional checks for trace ID to
TestHandler_SlowQueryLog