synapse/docs/metrics-howto.rst

How to monitor Synapse metrics using Prometheus

1. Install prometheus:

   Follow instructions at http://prometheus.io/docs/introduction/install/

2. Enable synapse metrics:

   Simply setting a (local) port number will enable it. Pick a port. prometheus itself defaults to 9090, so starting just above that for locally monitored services seems reasonable. E.g. 9092:

   Add to homeserver.yaml:

   metrics_port: 9092

   Also ensure that enable_metrics is set to True.

   Restart synapse.

3. Add a prometheus target for synapse.

   It needs to set the metrics_path to a non-default value:

   - job_name: "synapse"
     metrics_path: "/_synapse/metrics"
     static_configs:
       - targets:
           "my.server.here:9092"

   If your prometheus is older than 1.5.2, you will need to replace static_configs in the above with target_groups.

   Restart prometheus.

Standard Metric Names

As of synapse version 0.18.2, the format of the process-wide metrics has been changed to fit prometheus standard naming conventions. Additionally the units have been changed to seconds, from miliseconds.

New name	Old name
process_cpu_user_seconds_total	process_resource_utime / 1000
process_cpu_system_seconds_total	process_resource_stime / 1000
process_open_fds (no 'type' label)	process_fds

The python-specific counts of garbage collector performance have been renamed.

New name	Old name
python_gc_time	reactor_gc_time
python_gc_unreachable_total	reactor_gc_unreachable
python_gc_counts	reactor_gc_counts

The twisted-specific reactor metrics have been renamed.

New name	Old name
python_twisted_reactor_pending_calls	reactor_pending_calls
python_twisted_reactor_tick_time	reactor_tick_time