fix(topology): preserve component failure details

[gwenaskell]

Summary

Preserve runtime errors returned by sources and sinks in topology task failures. Existing components that return only () still produce an opaque task error. Bind failures from TCP/UDP socket, syslog, and StatsD sources, and WebSocket server and Prometheus exporter sinks, now include their causes. Console encoding and write errors, Kafka and MQTT subscription errors, journald checkpoint open errors, and AMQP consumer errors also retain their causes.

Log string panic payloads in a structured panic field when a source, transform, or sink task panics. Concurrent transform child panics reach the same handler. The panic payload does not enter the log message or shutdown reason.

Example runtime log

With a TCP socket source named in whose port is already held by another listener, the topology emitted this line in the regression test on macOS:

2026-10-13T12:55:13.816424Z ERROR source{component_kind="source" component_id=in component_type=socket}: vector::topology: An error occurred that Vector couldn't handle: TCP bind failed: Address already in use (os error 48).

The OS error number and text vary by platform.

A remap transform named grok, fed the message foo=NaN, also demonstrates the structured panic field:

pattern = "%{data::keyvalue}"
.result = parse_groks!(.message, patterns: [pattern])

The topology emitted this line:

2026-10-13T13:07:04.603990Z ERROR transform{component_kind="transform" component_id=grok component_type=remap}: vector::topology: An error occurred that Vector couldn't handle: the task panicked and was aborted. panic="not a float: FloatIsNan"

This reproduction uses parse_groks!, which runs the Datadog Grok keyvalue filter. parse_grok! uses standard Grok, where %{LOGLEVEL:keyvalue} names a capture.

References

None.

Vector configuration

Regression tests build topologies with TCP/UDP socket, syslog, and StatsD sources, and WebSocket server and Prometheus exporter sinks, while another listener holds the configured address. A console sink unit test closes its output pipe to check that the sink retains the original I/O error.

How did you test this PR?

• cargo test --no-default-features --features sources-socket,sinks-socket,sinks-websocket_server,test-utils --lib topology::test::crash:: -- --nocapture --test-threads=1 (7 passed)
• cargo test -p vector --no-default-features --features sources-socket,sources-syslog,sources-statsd,sources-kafka,sources-mqtt,sources-journald,sources-amqp,sinks-socket,sinks-websocket_server,sinks-prometheus,test-utils --lib topology::test::crash:: -- --test-threads=1 (10 passed)
• cargo test --no-default-features --features sources-socket,sinks-socket,sinks-websocket_server,test-utils --lib topology::test::panic:: -- --nocapture (2 passed)
• cargo test --no-default-features --features sources-socket,sources-syslog,sinks-socket,sinks-websocket_server,test-utils --lib test_udp_syslog_bind_error_is_reported -- --nocapture (1 passed)
• cargo test -p vector --no-default-features --features sinks-console write_error_retains_cause -- --nocapture (1 passed)
• cargo test -p vector --no-default-features --features sinks-console sinks::console::sink::test::component_spec_compliance (1 passed)
• FEATURES=sources-socket,sinks-socket,sinks-websocket_server,test-utils make check-clippy
• FEATURES=sinks-console make check-clippy
• FEATURES=sources-socket,sources-syslog,sources-statsd,sources-kafka,sources-mqtt,sources-journald,sources-amqp,sinks-socket,sinks-websocket_server,sinks-prometheus,test-utils make check-clippy
• make check-clippy (all features)
• Blackhole, Sematext logs, and Humio metrics smoke tests with sinks-blackhole,sinks-humio,sinks-sematext,aws-core,test-utils (3 passed)
• Built Vector with sources-stdin,transforms-remap,sinks-console and ran the foo=NaN remap configuration above; verified the topology log includes the panic field
• make check-fmt
• make check-changelog-fragments
• make check-markdown

Does this PR include user facing changes?

• Yes. Added a changelog fragment.
• No.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-13T13:02:44.930330Z	0486b9a	New commits

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[datadoghq-integration]

More details

The completed static review found the error adapters consistent with existing failure and shutdown behavior. Detailed causes are retained, while panic payloads remain outside shutdown reasons.

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