fix(up): drop benign context.Canceled noise from the final report - #14227
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The new TestUpAttachedTerminatesOnExternalStop (docker#13990) occasionally observed `up` exit 1 instead of 0 after an external stop/down cancels a service's restart backoff. The cause: once the monitor detects termination and cancels globalCtx, a log-streaming goroutine still blocked on logs?follow=1 for the backoff container gets a context.Canceled error, which appendErr collected unfiltered into the final errors.Join. That race could only surface once docker#13990 made the monitor loop actually return in this scenario -- before that fix, up hung forever and never reached this code path. appendErr now drops an error that is nothing more than fallout from our own shutdown (errors.Is(err, context.Canceled) once u.globalCtx.Err() is set), the same way a SIGINT-triggered teardown's residual goroutine errors are already expected to be harmless. A genuine error is still reported regardless of shutdown state. Signed-off-by: Nicolas De Loof <nicolas.deloof@gmail.com>
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Assessment: 🟢 APPROVE
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This is a direct follow-up to #13990.
Context
CI flaked right after #13990 merged:
TestUpAttachedTerminatesOnExternalStopfailed on thestandalonejob variants withupexiting 1 instead of 0, and this in the captured output:Once the monitor detects the container's restart backoff was canceled by an external
stop/downand returns,upcancelsglobalCtxto unwind its goroutines. The container's log-streaming goroutine (still blocked onlogs?follow=1waiting for output that will never come) gets acontext.Cancelederror from that cancellation, andappendErrcollected it unfiltered into the finalerrors.Join, turning what should be a clean, expected termination into a reported failure.This could only surface once #13990 made the monitor loop actually return in this scenario — before that fix
uphung forever and never reached this code path, so the race was unreachable.What this PR brings
appendErrnow drops an error that is nothing more than fallout fromup's own shutdown (errors.Is(err, context.Canceled)onceu.globalCtx.Err()is set) — the same treatment a SIGINT-triggered teardown's residual goroutine errors already get elsewhere. A genuine, unrelated error occurring after shutdown is still reported.🤖 Generated with Claude Code