docs/source/user-guide/metrics.md

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# Ballista Scheduler Metrics

## Prometheus

Built with default features, the ballista scheduler will automatically collect and expose a standard set of prometheus metrics.
The metrics currently collected automatically include:

- _job_exec_time_seconds_ - Histogram of successful job execution time in seconds
- _planning_time_ms_ - Histogram of job planning time in milliseconds
- _failed_ - Counter of failed jobs
- _job_failed_total_ - Counter of failed jobs
- _job_cancelled_total_ - Counter of cancelled jobs
- _job_completed_total_ - Counter of completed jobs
- _job_submitted_total_ - Counter of submitted jobs
- _pending_task_queue_size_ - Number of pending tasks

**NOTE** Currently the histogram buckets for the above metrics are set to reasonable defaults. If the defaults are not
appropriate for a given use case, the only workaround is to implement a customer `SchedulerMetricsCollector`. In the future
the buckets should be made configurable.

The metrics are then exported through the scheduler REST API at `GET /api/metrics`. It should be sufficient to ingest metrics
into an existing metrics system by point your chosen prometheus exporter at that endpoint.