Capture node output and report unexpected node exits - #53
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July 14, 2026 19:35
The node fixture spawned tenzir-node with piped stdout/stderr that nothing ever drained: node output beyond the kernel pipe buffer stalled the node's logging, the captured output was lost when the process went away, and a node that crashed mid-suite went entirely unnoticed -- dependent tests just failed with opaque connection errors. A CI investigation of a 10/10-attempt failure of a node-backed suite test ended inconclusive precisely because of this: the node's stderr, which would have shown whether the node crashed or wedged, was discarded. The fixture now pumps both streams into node-stdout.log and node-stderr.log next to the node's state directory, exposes the paths as TENZIR_NODE_STDOUT_LOG and TENZIR_NODE_STDERR_LOG to dependent tests, and logs an error with the exit code and a stderr tail when the node exits while the fixture is still active.
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Drain stderr during startup and coordinate watcher teardown. An already-finished node can no longer be mistaken for an intentional shutdown. Keep node logs when users pass --keep, and cover the lifecycle edge cases. Assisted-by: GPT-5 (Codex)
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The node fixture spawned
tenzir-nodewith piped stdout/stderr that nothing ever drained: node output beyond the kernel pipe buffer stalled the node's logging, the captured output was lost when the process went away, and a node that crashed mid-suite went entirely unnoticed — dependent tests just failed with opaque connection errors.A CI investigation of a 10/10-attempt failure of a node-backed suite test (job) ended inconclusive precisely because of this: the node's stderr, which would have shown whether the node crashed or wedged, was discarded.
With this change, the node fixture:
node-stdout.log/node-stderr.lognext to the node's state directory, so the node can never block on a full pipe and its output survives for diagnosis,TENZIR_NODE_STDOUT_LOG/TENZIR_NODE_STDERR_LOG, so tests can include node context in their own failure output, andThe pumps own and close their streams: closing a piped stream from another thread while a reader is blocked on it deadlocks on the stream's reader lock.
📚 Docs PR: tenzir/content#116