Short answer: you can’t change the hook signature—Prefect will only pass

flow

,

flow_run

, and

state

. But you can still access deployment context from inside the hook. Ways to get deployment info in an on_completion hook (Prefect 3.x): - From the runtime context: -

prefect.runtime.deployment

exposes

id

,

name

,

version

,

parameters

(None/empty if not running from a deployment) -

prefect.runtime.flow_run

exposes run fields like

id

,

name

,

parameters

, etc. - Docs: Runtime context, runtime.deployment API, runtime.flow_run API - From the

flow_run

argument: -

flow_run.deployment_id

,

flow_run.deployment_version

, plus other metadata fields - If you need to pass extra, custom data to the hook: - Pre-bind it when registering the hook (via

functools.partial

) - Or stash it during the flow run and read it in the hook (same process only) References for hooks: State-change hooks, Flow decorator and hooks API Examples - Access deployment context directly in the hook

from prefect import flow
from prefect.runtime import deployment

def on_complete(flow, flow_run, state):
    # Via runtime context (works only if triggered from a deployment)
    print("Deployment name:", deployment.name)
    print("Deployment id:", deployment.id)
    # Via flow_run object
    print("Deployment id from flow_run:", flow_run.deployment_id)
    print("Deployment version from flow_run:", flow_run.deployment_version)

@flow(on_completion=[on_complete])
def my_flow():
    ...

- Pass extra configuration to the hook

from functools import partial
from prefect import flow

def notifier(flow, flow_run, state, team="data-eng"):
    print(f"[{team}] Flow {flow.name} finished in state {state.name}")

@flow(on_completion=[partial(notifier, team="mlops")])
def my_flow():
    ...

- Stash data during the run for the hook to read later (same process)

from prefect import flow
from prefect.context import get_run_context

def on_complete(flow, flow_run, state):
    cfg = flow_run.context.get("hook_cfg", {})
    print("Hook cfg:", cfg)

@flow(on_completion=[on_complete])
def my_flow():
    ctx = get_run_context()
    ctx.flow_run.context["hook_cfg"] = {"alert_level": "critical"}
    ...

If you can share which “deployment context” fields you need (e.g., name, id, parameters, work pool/queue), I can suggest the most direct access pattern.

Yes—while the hook signature can’t be changed (it only receives

flow

,

flow_run

,

state

), you can get the deployment name inside the hook. Fast path (when running from a deployment):

from prefect.runtime import deployment

def on_complete(flow, flow_run, state):
    dep_name = deployment.name  # None if not running via a deployment
    print("Deployment name:", dep_name)

Robust path (fallback to the API if needed):

from prefect.runtime import deployment

async def on_complete(flow, flow_run, state):
    name = deployment.name
    if not name and flow_run.deployment_id:
        from prefect.client.orchestration import get_client
        async with get_client() as client:
            dep = await client.read_deployment(flow_run.deployment_id)
            name = dep.name
    print("Deployment name:", name)

Docs: - State-change hooks - Runtime context - runtime.deployment API