Yes — you can do this on a self-hosted Prefect server using an automation that listens for the

prefect.flow-run.Completed

event and then runs a deployment. The basic pattern is: 1. A flow run finishes and enters

Completed

2. Prefect emits the

prefect.flow-run.Completed

event 3. An automation catches that event 4. The automation runs another deployment Important: automations trigger deployments, not ad hoc raw flow functions. So the “new run” should come from a deployment you want to launch. Example automation YAML:

yaml
name: rerun-on-completion
enabled: true

trigger:
  type: event
  posture: Reactive
  expect:
    - prefect.flow-run.Completed
  match_related:
    prefect.resource.name: "my-flow"
    prefect.resource.role: "flow"
  threshold: 1
  within: 0

actions:
  - type: run-deployment
    source: selected
    deployment_id: "YOUR_DEPLOYMENT_ID"

Then create it with:

bash
prefect automation create --from-file automation.yaml

I verified the CLI exists: -

prefect automation

-

prefect automation create --from-file ...

A few notes: If you want the flow to trigger itself again You can point

deployment_id

at the same deployment. That will create a loop, so be careful — it will keep launching new runs every time one completes. If you want flow A to trigger flow B Set the

deployment_id

to flow B’s deployment. If you only want this for one specific upstream deployment You can filter more narrowly using related deployment info instead of just the flow name. A common setup is:

yaml
name: chain-flow-runs
enabled: true

trigger:
  type: event
  posture: Reactive
  expect:
    - prefect.flow-run.Completed
  match_related:
    prefect.resource.name: "upstream-flow"
    prefect.resource.role: "flow"
  threshold: 1
  within: 0

actions:
  - type: run-deployment
    source: selected
    deployment_id: "DOWNSTREAM_DEPLOYMENT_ID"

Useful docs: - Automations concepts - Event triggers - Creating automations - Chaining deployments with events If you want, I can also help you write the exact automation YAML for: - rerunning the same deployment, or - triggering a different deployment after completion.

Yes — the way to distinguish which deployment produced the completed flow run is to filter on the related deployment resource, not just on the flow-run state. In Prefect, a

prefect.flow-run.Completed

event is about the flow run, but that event also includes related resources like: - the flow - the deployment - possibly work pool, tags, etc. So if your flow has two deployments, you want your automation trigger to say: - event must be

prefect.flow-run.Completed

- and one of the related resources must be the specific deployment you care about Use

match_related

for that. Example trigger JSON:

json
{
  "type": "event",
  "posture": "Reactive",
  "expect": ["prefect.flow-run.Completed"],
  "match": {
    "prefect.resource.id": "prefect.flow-run.*"
  },
  "match_related": {
    "prefect.resource.id": "prefect.deployment.YOUR_DEPLOYMENT_ID"
  },
  "threshold": 1,
  "within": 0
}

You can also filter by deployment name instead of ID:

json
{
  "type": "event",
  "posture": "Reactive",
  "expect": ["prefect.flow-run.Completed"],
  "match": {
    "prefect.resource.id": "prefect.flow-run.*"
  },
  "match_related": {
    "prefect.resource.name": "my-specific-deployment"
  },
  "threshold": 1,
  "within": 0
}

Why the UI feels limited The UI’s simple form often only exposes the state/event selector. To target a specific deployment, you usually need to switch to the custom JSON/YAML-style trigger config and add

match_related

. So your automation should be: - Trigger:

prefect.flow-run.Completed

- Filter:

match_related

on the upstream deployment - Action:

run-deployment

for the downstream flow’s deployment Example full automation YAML:

yaml
name: upstream-deployment-a-completed
enabled: true

trigger:
  type: event
  posture: Reactive
  expect:
    - prefect.flow-run.Completed
  match:
    prefect.resource.id: prefect.flow-run.*
  match_related:
    prefect.resource.id: prefect.deployment.UPSTREAM_DEPLOYMENT_ID
  threshold: 1
  within: 0

actions:
  - type: run-deployment
    source: selected
    deployment_id: DOWNSTREAM_DEPLOYMENT_ID

A couple practical tips: - Best filter:

prefect.resource.id

with the full deployment ID, since names can change - Good enough sometimes:

prefect.resource.name

if you want something easier to read - If you only use flow-level matching, both deployments of that flow can trigger it How to find the upstream deployment ID: - in the deployment page/details in the UI - or via

prefect deployment ls

If you want, I can help you write the exact JSON/YAML for your two deployments if you share: - upstream deployment name - downstream deployment name

Yes — here are the relevant Prefect docs/source-backed references for using

match_related

to filter on a deployment related to a flow-run event: Docs - Event triggers — explains

match

vs

match_related

for event triggers - Creating automations — shows how automations are defined with event trigger fields - Chaining deployments with events — relevant pattern for triggering one deployment from another deployment’s events Source / implementation -

prefect.events.schemas.automations.EventTrigger

— this is the trigger schema that includes

match

and

match_related

-

prefect.events.schemas.events.ResourceSpecification

— this is the resource matching structure used for those fields If you want the most direct wording, the key concept is: -

match

filters the primary resource for the event -

match_related

filters related resources included with the event For a

prefect.flow-run.Completed

event: - the primary resource is the flow run - the deployment is a related resource So filtering a specific upstream deployment is done with

match_related

, e.g.:

yaml
match_related:
  prefect.resource.id: prefect.deployment.<deployment-id>

If you'd like, I can also give you a copy-paste quote from the relevant doc section formatted for an internal note or PR comment.