Recover from UDS socket loss by making BadSocketError retryable#330
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Recover from UDS socket loss by making BadSocketError retryable#330joshuay03 wants to merge 1 commit into
BadSocketError retryable#330joshuay03 wants to merge 1 commit into
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UDSConnection raises BadSocketError when sendmsg_nonblock hits ECONNREFUSED, ECONNRESET, or ENOENT, but Connection#write's retry list did not include it, so the socket was never closed and every subsequent send failed the same way for the lifetime of the process. Introduce Connection::RetryableError and make BadSocketError inherit from it. Connection#write now closes and reconnects before retrying.
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BadSocketError retryable
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Pull request overview
This PR makes UDS socket failures recoverable by introducing a Connection::RetryableError base class, making UDSConnection::BadSocketError inherit from it, and teaching Connection#write to retry (close + reconnect) when that error occurs—preventing long-lived “wedged” sockets after a Datadog Agent restart.
Changes:
- Add
Datadog::Statsd::Connection::RetryableErrorand retry it inConnection#write. - Make
Datadog::Statsd::UDSConnection::BadSocketErrorinherit fromRetryableError(so UDS send failures trigger reconnect). - Update UDS specs to assert successful retry/close behavior and adjust telemetry/logging expectations; add changelog entry.
Reviewed changes
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Show a summary per file
| File | Description |
|---|---|
| lib/datadog/statsd/connection.rb | Introduces RetryableError and retries it in #write by closing and reconnecting once. |
| lib/datadog/statsd/uds_connection.rb | Makes BadSocketError retryable by inheriting from RetryableError. |
| spec/statsd/uds_connection_spec.rb | Converts previously pending/negative cases into assertions for retry, close-on-reconnect, logging, and telemetry. |
| spec/integrations/connection_edge_case_spec.rb | Updates integration coverage to assert the new retry/close behavior and logging for UDS edge cases. |
| CHANGELOG.md | Documents the UDS recovery bugfix under “Unreleased” and adds reference links. |
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We ran into this at @buildkite when the Datadog Agent restarted on one of our nodes: every
Datadog::Statsdinstance in our Ruby process stayed wedged on the dead socket fd and dropped custom metrics until the app restarted.UDSConnection#send_messagewrapsErrno::ECONNREFUSED,Errno::ECONNRESET, andErrno::ENOENTasBadSocketError, butConnection#write's retry list did not include it, so the socket was never closed.This PR introduces
Connection::RetryableError, makesBadSocketErrorinherit from it, and adds it to the retry list. The existing TODO inUDSConnection#send_messageand the# FIXME: BadSocketError is not correctly caught by Connection class to retrynotes in the UDS specs already recommended this shape; the previouslypending: trueand "does not correctly retry" specs flip to positive assertions.