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Worker Groups

Windmill allows you to run your scripts and flows on different machines with different specs. This is useful if you want to run some scripts on a GPU machine, or if you want to run some scripts on a machine with a lot of memory.

Individual scripts saved on a workspace and inline scripts of a flow can be assigned a custom worker group. By default, they are assigned the worker group that correspond to their languages.

Workers can be assigned to different worker groups at the same time. The default worker groups a worker is part of are:

  • dependency: Where dependency jobs are run.
  • deno: The default worker group for deno scripts.
  • python3: The default worker group for python scripts.
  • bash: The default worker group for bash scripts.
  • go: The default worker group for go scripts.
  • flow: The default worker group for executing flows modules outside of the script steps.
  • hub: The default worker group for executing hub scripts.

If you assign custom worker groups to all your workers, make sure that they cover all worker groups above, otherwise those jobs will never be executed.

You can customize the worker group of a worker by passing as env variable:


The default WORKER_TAGS of workers is deno,python3,bash,go,flow,hub,dependency.

The configuration above will make the workers accept only deno jobs and jobs with the light tag.

To make custom tags selectable from the UI, you need to pass the following env variable to the windmill server:


How to assign a custom worker group to a script‚Äč

For scripts saved on the script editor, select the corresponding worker group tag in the metadata section.

Worker group tag

For scripts inlined in the flow editor, select it in the module header:

Worker group tag

If no worker group is assigned to a script, it will be assigned the default worker group for its language.