Scheduler Logs

Each workflow maintains its own log of time-stamped events in the workflow log directory ($HOME/cylc-run/<workflow-id>/log/scheduler/).

The information logged here includes:

  • Event timestamps, at the start of each line

  • Workflow server host, port and process ID

  • Workflow initial and final cycle points

  • Workflow (re)start number (1 for the first play, 2 or more for restarts)

  • Task events (task started, succeeded, failed, etc.)

  • Workflow stalled warnings.

  • Client commands (e.g. cylc hold)

  • Job IDs.

  • Information relating to the remote file installation is contained in a separate log file, which can be found in $HOME/cylc-run/<workflow-id>/log/remote-install/.


Workflow log files are primarily intended for human eyes. If you need to have an external system to monitor workflow events automatically, use:

Rather than parse the log files.

Cylc Message

The Scheduler Log also records messages sent by cylc message allowing you to add custom messages to this log.

For example, if your task contained the following code:

cylc message -- "ERROR:some_function failed."

Your log should produce output similar to:

ERROR - [21491012T0410Z/mytask running job:01 flows:1] (received)some_function failed ERROR at 2023-04-14T11:36:35+01:00

Severity levels are the same as those used by Python’s logger:




  • INFO


Messages logged at “DEBUG” will only appear in the scheduler log if the workflow is played with cylc play --debug.