Add heartbeats to StreamBuildEvents wait-for-log-file loop#176
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hiroTamada wants to merge 1 commit intomainfrom
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Add heartbeats to StreamBuildEvents wait-for-log-file loop#176hiroTamada wants to merge 1 commit intomainfrom
hiroTamada wants to merge 1 commit intomainfrom
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When a build is queued, StreamBuildEvents waits for the log file to appear before streaming logs. During this wait, no events are sent on the SSE connection. Infrastructure proxies (e.g. Railway) terminate idle SSE connections after ~60 seconds, causing the Kernel API to see a "build timed out" error even though the build hasn't started yet. Add a 15-second heartbeat ticker to keep the SSE connection alive while waiting for the log file. The existing 30-second heartbeat in the main streaming loop already handles the active-build case. Made-with: Cursor
Sayan-
approved these changes
Mar 30, 2026
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| select { | ||
| case out <- BuildEvent{Type: EventTypeHeartbeat, Timestamp: time.Now()}: | ||
| case <-ctx.Done(): | ||
| return | ||
| } |
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inner select seems redundant relative to the outer but nbd
| } | ||
| break | ||
| } | ||
| waitHeartbeat.Stop() |
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Summary
StreamBuildEventswait-for-log-file loopContext
During a bulk migration of Unikraft deployments to Hypeman, builds queued behind others consistently timed out after exactly 60 seconds. Root cause: the SSE stream was idle during the queue wait, triggering an infrastructure idle timeout.
Test plan
max_concurrent_source_builds) to force queuingMade with Cursor
Note
Low Risk
Low risk, localized change to
StreamBuildEventsthat only adds periodic heartbeat events during the pre-log wait; main behavioral risk is extra event traffic or unexpected client handling ofheartbeatevents.Overview
Prevents idle timeouts for queued builds by emitting
heartbeatevents whileStreamBuildEventsis waiting for the build log file to appear.This adds a 15s ticker in the wait-for-log-file loop (before
tailstarts) so SSE clients keep receiving events until logs begin streaming or the build reaches a terminal status.Written by Cursor Bugbot for commit bffcd3e. This will update automatically on new commits. Configure here.