[AIRFLOW-5269] Reuse session in Scheduler Job from health endpoint

[kaxil]

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Jira

• My PR addresses the following Airflow Jira issues and references them in the PR title. For example, "[AIRFLOW-XXX] My Airflow PR"
  • https://issues.apache.org/jira/browse/AIRFLOW-5269

Description

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  Reuse session in Scheduler Job from health endpoint

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  Current tests cover it

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Code Quality

• Passes flake8

[Fokko]

I would remove the decorator from the whole /health endpoint:

class Airflow(AirflowBaseView):
    @expose('/health')
    @provide_session
    def health(self, session=None):
        """
        An endpoint helping check the health status of the Airflow instance,
        including metadatabase and scheduler.
        """

        payload = {
            'metadatabase': {'status': 'unhealthy'}
        }

        latest_scheduler_heartbeat = None
        scheduler_status = 'unhealthy'
        payload['metadatabase'] = {'status': 'healthy'}
        try:
            scheduler_job = jobs.SchedulerJob.most_recent_job(session=session)

            if scheduler_job:
                latest_scheduler_heartbeat = scheduler_job.latest_heartbeat.isoformat()
                if scheduler_job.is_alive():
                    scheduler_status = 'healthy'
        except Exception:
            payload['metadatabase']['status'] = 'unhealthy'

        payload['scheduler'] = {'status': scheduler_status,
                                'latest_scheduler_heartbeat': latest_scheduler_heartbeat}

        return wwwutils.json_response(payload)

We don't use the session anywhere in the function. This will only keep the session open inside the scope of the most_recent_job() function. WDYT @kaxil ?

[kaxil]

@Fokko Updated

[Fokko]

LGTM! 👍