Worker and runner events - Prefect

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`)

Related resources

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.

Related resources

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.

Related resources

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.

Related resources

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.

json

{
  "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"
}

</Expandable>

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

Related resources

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.