Yes — you can configure it in your project config file, but not in

prefect.yaml

. For Prefect 3.x,

PREFECT_WORKER_WEBSERVER_PORT

is a runtime setting for the worker process. That means it’s read from Prefect’s settings system when the worker starts, not from deployment config in

prefect.yaml

. You have a few valid options: Environment variable

bash
export PREFECT_WORKER_WEBSERVER_PORT=9090
prefect worker start --pool my-pool --with-healthcheck

Project

prefect.toml

toml
[worker.webserver]
port = 9090

Also supported: -

.env

- active Prefect profile via

prefect config set

-

pyproject.toml

Important distinction: -

prefect.yaml

= deployment/project orchestration config -

PREFECT_WORKER_WEBSERVER_PORT

= worker process setting So if you're asking whether it must be in the shell script/environment that starts the worker: not necessarily. It can live in

prefect.toml

instead. But it does need to be available through Prefect settings at worker startup. Relevant docs: - Settings reference - Workers If you want, I can also show exactly how

prefect.yaml

and

prefect.toml

should coexist in the same project.