Operations & Maintenance

ArangoSync is a distributed system with a lot different components. As with any such system, it requires some, but not a lot of operational support.

What means are available to monitor status

All of the components of ArangoSync provide means to monitor their status. Below you’ll find an overview per component.

• Sync master & workers: The arangosync servers running as either master or worker, provide:
  • A status API, see arangosync get status. Make sure that all statuses report running.
    For even more detail the following commands are also available: arangosync get tasks, arangosync get masters & arangosync get workers.
  • A log on the standard output. Log levels can be configured using --log.level settings.
  • A metrics API GET /metrics. This API is compatible with Prometheus. Sample Grafana dashboards for inspecting these metrics are available.
• ArangoDB cluster: The arangod servers that make up the ArangoDB cluster provide:
  • A log file. This is configurable with settings with a log. prefix. E.g. --log.output=file://myLogFile or --log.level=info.
  • A statistics API GET /_admin/statistics

What to look for while monitoring status

The very first thing to do when monitoring the status of ArangoSync is to look into the status provided by arangosync get status ... -v. When not everything is in the running state (on both datacenters), this is an indication that something may be wrong. In case that happens, give it some time (incremental synchronization may take quite some time for large collections) and look at the status again. If the statuses do not change (or change, but not reach running) it is time to inspects the metrics & log files.
When the metrics or logs seem to indicate a problem in a sync master or worker, it is safe to restart it, as long as only 1 instance is restarted at a time. Give restarted instances some time to “catch up”.

‘What if …’

Please consult the troubleshooting section for detailed descriptions of what to do in case of certain problems, and how and what information to provide to support so they can assist you best when needed.

Metrics

ArangoSync (master & worker) provide metrics that can be used for monitoring the ArangoSync solution. These metrics are available using the following HTTPS endpoints:

• GET /metrics: Provides metrics in a format supported by Prometheus.
• GET /metrics.json: Provides the same metrics in JSON format.

Both endpoints include help information per metrics.

Note: Both endpoints require authentication. Besides the usual authentication methods these endpoints are also accessible using a special bearer token specified using the --monitoring.token command line option.

Consult the monitoring section for sample output of the metrics endpoints.