Worker and runner events

Worker events track the lifecycle of worker processes and the flow runs they execute. Runner events cover flow run cancellation by locally-served deployments. For more on workers, see Workers.

Worker events

`prefect.worker.started`

Emitted when a worker process starts polling for work.

Resource

Label	Description
`prefect.resource.id`	`prefect.worker.{type}.{name-slug}`
`prefect.resource.name`	Worker name
`prefect.version`	Prefect SDK version
`prefect.worker-type`	Worker type (for example, `kubernetes`, `process`, `docker`)

Resource ID pattern	Role	When present
`prefect.work-pool.{uuid}`	`work-pool`	When the worker is attached to a work pool

Payload

This event has no payload.

`prefect.worker.stopped`

Emitted when a worker process shuts down. Uses the follows field to link back to the corresponding started event.

Resource

Same as prefect.worker.started. Same as prefect.worker.started.

Payload

This event has no payload.

`prefect.worker.submitted-flow-run`

Emitted when a worker submits a flow run for execution on infrastructure.

Resource

Same as prefect.worker.started.

Resource ID pattern	Role	When present
`prefect.flow-run.{uuid}`	`flow-run`	Always
`prefect.flow.{uuid}`	`flow`	Always
`prefect.deployment.{uuid}`	`deployment`	When triggered by a deployment
`prefect.work-pool.{uuid}`	`work-pool`	When attached to a work pool
`prefect.tag.{tag}`	`tag`	One entry per tag

Payload

This event has no payload.

`prefect.worker.executed-flow-run`

Emitted when a worker finishes executing a flow run (regardless of outcome). Uses the follows field to link back to the corresponding submitted-flow-run event.

Resource

Same as prefect.worker.started. Same as prefect.worker.submitted-flow-run, with additional labels on the flow-run related resource:

Additional label	Description
`prefect.infrastructure.identifier`	Infrastructure-specific identifier for the execution (for example, process PID)
`prefect.infrastructure.status-code`	Exit status code of the infrastructure process

Payload

This event has no payload.

Show Example: worker executed a flow run

{
  "occurred": "2026-03-31T18:35:00.000000Z",
  "event": "prefect.worker.executed-flow-run",
  "resource": {
    "prefect.resource.id": "prefect.worker.kubernetes.my-k8s-worker",
    "prefect.resource.name": "my-k8s-worker",
    "prefect.version": "3.6.0",
    "prefect.worker-type": "kubernetes"
  },
  "related": [
    {
      "prefect.resource.id": "prefect.flow-run.e3755d32-cec5-42ca-9bcd-af236e308ba6",
      "prefect.resource.name": "crimson-fox",
      "prefect.resource.role": "flow-run",
      "prefect.infrastructure.identifier": "my-job-abc123",
      "prefect.infrastructure.status-code": "0"
    },
    {
      "prefect.resource.id": "prefect.work-pool.c3d4e5f6-a7b8-9012-cdef-123456789012",
      "prefect.resource.name": "my-k8s-pool",
      "prefect.resource.role": "work-pool"
    }
  ],
  "id": "d4e5f6a7-b890-1234-5678-9012abcdef34",
  "follows": "c3d4e5f6-a7b8-9012-cdef-123456789012"
}

Runner events

`prefect.runner.cancelled-flow-run`

Emitted when a runner cancels a flow run that was being served locally via flow.serve() or the Runner API.

Resource

Label	Description
`prefect.resource.id`	`prefect.runner.{name-slug}`
`prefect.resource.name`	Runner name
`prefect.version`	Prefect SDK version

Resource ID pattern	Role	When present
`prefect.deployment.{uuid}`	`deployment`	When the flow run was triggered by a deployment
`prefect.flow.{uuid}`	`flow`	When the flow is known
`prefect.flow-run.{uuid}`	`flow-run`	Always
`prefect.tag.{tag}`	`tag`	One entry per tag from the flow run and deployment

Payload

This event has no payload.

API Reference

​Worker events

​prefect.worker.started

​Resource

​Related resources

​Payload

​prefect.worker.stopped

​Resource

​Related resources

​Payload

​prefect.worker.submitted-flow-run

​Resource

​Related resources

​Payload

​prefect.worker.executed-flow-run

​Resource

​Related resources

​Payload

​Runner events

​prefect.runner.cancelled-flow-run

​Resource

​Related resources

​Payload

Worker events

`prefect.worker.started`

Resource

Related resources

Payload

`prefect.worker.stopped`

Resource

Related resources

Payload

`prefect.worker.submitted-flow-run`

Resource

Related resources

Payload

`prefect.worker.executed-flow-run`

Resource

Related resources

Payload

Runner events

`prefect.runner.cancelled-flow-run`

Resource

Related resources

Payload