Fix triggerer CrashLoopBackOff when json_logs is enabled

[safaehar]

What

TriggerRunnerSupervisor._process_log_messages_from_subprocess primes itself by calling airflow.sdk.log.configure_logging() with no arguments. json_output defaults to False, so this call reconfigures structlog globally and installs the text WriteLogger factory — overwriting the bytes BytesLogger factory that startup set up when [logging] json_logs = True.

The stdout/stderr forwarders (_create_log_forwarder → forward_to_log) are already wrapped with the JSON (bytes) processor chain but bind their underlying logger lazily. As soon as a trigger subprocess writes to stdout/stderr — e.g. an import-time DeprecationWarning from a provider trigger that imports a heavy client such as KubernetesPodTrigger (kubernetes) or S3KeyTrigger (boto3) — the lazy bind resolves against the now-text factory, and WriteLogger.msg does message + "\n" on bytes produced by the JSON renderer:

TypeError: can't concat str to bytes
  File ".../structlog/_output.py", line 217, in msg
    self._write(message + "\n")

This crashes the TriggerRunnerSupervisor.run loop and the triggerer enters CrashLoopBackOff. It only manifests when json_logs is enabled and the triggerer actually runs a trigger whose subprocess emits to stdout/stderr — idle triggerers and those running only quiet triggers (DateTimeTrigger, etc.) never reach forward_to_log, which is why the crash looks intermittent across deployments.

Fix

Pass json_output from the [logging] json_logs config (the same conf.getboolean("logging", "json_logs", fallback=False) used elsewhere, e.g. airflow/logging_config.py) so the global structlog factory stays consistent with the rest of the process. This matches the already-hardcoded logging_processors(json_output=True) a few lines below.

Tests

Adds a parametrized regression test asserting _process_log_messages_from_subprocess calls configure_logging(json_output=<json_logs>) for both True and False.

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[Copilot]

Pull request overview

Fixes a triggerer CrashLoopBackOff that occurs when [logging] json_logs = True by ensuring the triggerer’s subprocess log-message processor reconfigures structlog with a json_output value that matches the Airflow json_logs setting (preventing a bytes-renderer/text-logger mismatch). Adds a targeted regression test and a user-facing newsfragment.

Changes:

• Pass json_output=conf.getboolean("logging", "json_logs", fallback=False) to airflow.sdk.log.configure_logging() when priming _process_log_messages_from_subprocess.
• Add a parametrized unit regression test asserting configure_logging(json_output=<json_logs>) for both True and False.
• Add an airflow-core bugfix newsfragment describing the triggerer crash and fix.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
airflow-core/src/airflow/jobs/triggerer_job_runner.py	Aligns structlog reconfiguration with [logging] json_logs to prevent bytes/text logger factory mismatch during subprocess log forwarding.
airflow-core/tests/unit/jobs/test_triggerer_job.py	Adds a regression test ensuring the generator priming path calls configure_logging with json_output matching json_logs.
airflow-core/newsfragments/68584.bugfix.rst	Documents the user-visible triggerer CrashLoopBackOff bugfix.

[SameerMesiah97]

Looks good. Just one nit.

[hussein-awala]

Change looks good, LGTM once the newsfragment is removed

[github-actions]

Backport successfully created: v3-3-test

Note: As of Merging PRs targeted for Airflow 3.X
the committer who merges the PR is responsible for backporting the PRs that are bug fixes (generally speaking) to the maintenance branches.

In matter of doubt please ask in #release-management Slack channel.

Status	Branch	Result
✅	v3-3-test