Infrastructure events - Prefect

Infrastructure events cover block loading, deployment pull step execution, workspace resource transfers, and infrastructure status tracking from integration packages. For more on blocks, see Blocks.

Block events

`prefect.block.{type}.loaded`

Emitted when a block is loaded from the server. The {type} portion is the block type slug (for example, prefect.block.slack-webhook.loaded or prefect.block.s3-bucket.loaded).

Resource

Label	Description
`prefect.resource.id`	`prefect.block-document.{uuid}`
`prefect.resource.name`	Block document name

Related resources

Resource ID pattern	Role	When present
`prefect.block-type.{slug}`	`block-type`	Always

Payload

This event has no payload.

<Note> Block subclasses can override the `_event_method_called_resources()` method to customize the resource and related resources for their events. </Note>

Deployment pull step events

`prefect.flow-run.pull-step.executed`

Emitted when a deployment pull step completes successfully during flow run infrastructure setup.

Resource

Label	Description
`prefect.resource.id`	`prefect.flow-run.{uuid}`

Related resources

Resource ID pattern	Role	When present
`prefect.deployment.{uuid}`	`deployment`	When the deployment is known

Payload

The payload contains the serialized step definition (the step's fully qualified name and its input parameters as defined in prefect.yaml).

`prefect.flow-run.pull-step.failed`

Emitted when a deployment pull step fails during flow run infrastructure setup.

Workspace transfer events

`prefect.workspace.transfer.started`

Emitted when a workspace-to-workspace resource transfer begins (via prefect transfer).

Resource

Label	Description
`prefect.resource.id`	`prefect.workspace.transfer.{uuid}`
`prefect.resource.name`	Description of the transfer direction (for example, `local → cloud/my-workspace`)

Related resources

This event has no related resources.

Payload

Field	Type	Description
`source_profile`	string	Name of the source Prefect profile
`target_profile`	string	Name of the target Prefect profile
`source_url`	string	API URL of the source
`target_url`	string	API URL of the target
`total_resources`	integer	Total number of resources to transfer

`prefect.workspace.transfer.completed`

Emitted when a workspace transfer completes.

Resource

Same as prefect.workspace.transfer.started.

Related resources

This event has no related resources.

Payload

Field	Type	Description
`source_profile`	string	Name of the source Prefect profile
`target_profile`	string	Name of the target Prefect profile
`source_url`	string	API URL of the source
`target_url`	string	API URL of the target
`total_resources`	integer	Total number of resources transferred
`succeeded`	integer	Number of resources transferred successfully
`failed`	integer	Number of resources that failed to transfer
`skipped`	integer	Number of resources skipped

Integration infrastructure events

The following events are emitted by Prefect integration packages to track infrastructure status changes during flow run execution. Each requires the respective integration package to be installed.

Docker events (prefect-docker)

The Docker worker emits events when container status changes during flow run execution.

`prefect.docker.container.{status}`

Emitted when a Docker container's status changes. Events are chained using the follows field to track status progression.

Status variants

Event name	Description
`prefect.docker.container.created`	Container has been created
`prefect.docker.container.running`	Container is running
`prefect.docker.container.paused`	Container is paused
`prefect.docker.container.restarting`	Container is restarting
`prefect.docker.container.removing`	Container is being removed
`prefect.docker.container.exited`	Container has exited
`prefect.docker.container.dead`	Container is in a dead state

Resource

Label	Description
`prefect.resource.id`	`prefect.docker.container.{container-id}`
`prefect.resource.name`	Container name

Related resources

Resource ID pattern	Role	When present
`prefect.flow-run.{uuid}`	`flow-run`	When available from worker configuration
`prefect.flow.{uuid}`	`flow`	When available
`prefect.deployment.{uuid}`	`deployment`	When available
`prefect.work-pool.{uuid}`	`work-pool`	When the worker is attached to a work pool
Worker resource	`worker`	Always (the worker that manages the container)

Payload

This event has no payload.

`prefect.docker.container.creation-failed`

Emitted when a Docker container fails to be created. Same resource and related resources as prefect.docker.container.{status}.

Kubernetes events (prefect-kubernetes)

The Kubernetes observer emits events when pod phase changes are detected for pods labeled with prefect.io/flow-run-id.

`prefect.kubernetes.pod.{phase}`

Emitted when a Kubernetes pod transitions to a new phase. Events use deterministic IDs based on the pod UID, phase, and restart count for deduplication. Events within 5 minutes of each other are chained using the follows field.

Phase variants

Event name	Description
`prefect.kubernetes.pod.pending`	Pod is in the Pending phase
`prefect.kubernetes.pod.running`	Pod is in the Running phase
`prefect.kubernetes.pod.succeeded`	Pod completed successfully
`prefect.kubernetes.pod.failed`	Pod terminated with an error
`prefect.kubernetes.pod.unknown`	Pod is in an unknown state
`prefect.kubernetes.pod.evicted`	Pod was evicted from the node

Resource

Label	Description
`prefect.resource.id`	`prefect.kubernetes.pod.{uid}`
`prefect.resource.name`	Pod name
`kubernetes.namespace`	Kubernetes namespace
`kubernetes.reason`	Eviction reason (only for evicted pods)

Related resources

Resource ID pattern	Role	When present
`prefect.flow-run.{uuid}`	`flow-run`	Always (from `prefect.io/flow-run-id` pod label)
`prefect.deployment.{uuid}`	`deployment`	When `prefect.io/deployment-id` pod label is set
`prefect.flow.{uuid}`	`flow`	When `prefect.io/flow-id` pod label is set
`prefect.work-pool.{uuid}`	`work-pool`	When `prefect.io/work-pool-id` pod label is set
Worker name	`worker`	When `prefect.io/worker-name` pod label is set (includes `prefect.worker-type: kubernetes`)

Payload

This event has no payload.

json

{
  "occurred": "2026-03-31T18:30:00.000000Z",
  "event": "prefect.kubernetes.pod.running",
  "resource": {
    "prefect.resource.id": "prefect.kubernetes.pod.a1b2c3d4-e5f6-7890-abcd-ef1234567890",
    "prefect.resource.name": "prefect-flow-run-abc123",
    "kubernetes.namespace": "prefect"
  },
  "related": [
    {
      "prefect.resource.id": "prefect.flow-run.e3755d32-cec5-42ca-9bcd-af236e308ba6",
      "prefect.resource.role": "flow-run"
    },
    {
      "prefect.resource.id": "prefect.work-pool.c3d4e5f6-a7b8-9012-cdef-123456789012",
      "prefect.resource.role": "work-pool"
    },
    {
      "prefect.resource.id": "my-k8s-worker",
      "prefect.resource.role": "worker",
      "prefect.worker-type": "kubernetes"
    }
  ],
  "id": "b890c123-4567-89ab-cdef-0123456789ab",
  "follows": "a7890123-bcde-f456-7890-123456789abc"
}

</Expandable>

AWS ECS events (prefect-aws)

The ECS observer emits events when ECS task status changes are detected via SQS for tasks tagged with prefect.io/flow-run-id.

`prefect.ecs.task.{status}`

Emitted when an ECS task transitions to a new status. Events use the AWS EventBridge event UUID for deterministic tracking. Events within 5 minutes of each other are chained using the follows field.

Status variants

Event name	Description
`prefect.ecs.task.provisioning`	Task resources are being provisioned
`prefect.ecs.task.pending`	Task is waiting to be placed on a container instance
`prefect.ecs.task.activating`	Task is being activated
`prefect.ecs.task.running`	Task is running
`prefect.ecs.task.deactivating`	Task is being deactivated
`prefect.ecs.task.stopping`	Task is being stopped
`prefect.ecs.task.deprovisioning`	Task resources are being deprovisioned
`prefect.ecs.task.stopped`	Task has stopped
`prefect.ecs.task.deleted`	Task has been deleted

Resource

Label	Description
`prefect.resource.id`	`prefect.ecs.task.{task-id}`
`ecs.taskArn`	Full ECS task ARN
`ecs.clusterArn`	ECS cluster ARN (when available)
`ecs.taskDefinitionArn`	ECS task definition ARN (when available)

Related resources

Resource ID pattern	Role	When present
`prefect.flow-run.{uuid}`	`flow-run`	Always (from `prefect.io/flow-run-id` task tag)
`prefect.deployment.{uuid}`	`deployment`	When `prefect.io/deployment-id` task tag is set
`prefect.flow.{uuid}`	`flow`	When `prefect.io/flow-id` task tag is set
`prefect.work-pool.{uuid}`	`work-pool`	When `prefect.io/work-pool-id` task tag is set
Worker name	`worker`	When `prefect.io/worker-name` task tag is set (includes `prefect.worker-type: ecs`)

Payload

This event has no payload.