Is there a way to automatically run docker system prune -af after a workflow completes

[b-gonzalez]

When I run a workflow with Nektos Act, it creates a bunch of docker images. After the workflow completes, I can either manually delete these images using Docker Desktop or run docker system prune -af. Is there a way I can run docker system prune -af after the workflow completes or delete the images created in the workflow run some other automated way?

[starkmarkus]

I would be a little careful with docker system prune -af, because that is global Docker cleanup, not just cleanup for this one act run. It can remove images/containers/build cache that were created by other projects too.

If you still want that behavior, the simplest approach is probably to wrap act in a shell script, for example:

#!/usr/bin/env bash
set -e
act "$@"
docker system prune -af

or, if you want cleanup even when the workflow fails:

#!/usr/bin/env bash
set +e
act "$@"
status=$?
docker system prune -af
exit $status

That said, I think a safer built-in feature would be an act option to clean only the containers/images/networks created for that run, or to label all act-created Docker resources so users can prune only those labels afterwards.

Something like this would be much safer than a global prune:

docker image prune -af --filter "label=act"
docker container prune -f --filter "label=act"
docker network prune -f --filter "label=act"

assuming act applied a consistent label to the resources it creates.

So today I would use a wrapper script if you really want automatic cleanup, but I would avoid recommending docker system prune -af as a default because it affects the whole Docker daemon. A scoped cleanup option or consistent Docker labels would be the better long-term solution.

[b-gonzalez]

Thanks for the info. I will update my process.

[starkmarkus]

Glad that helped.

Just to summarize the practical answer for anyone finding this later: I do not think there is currently a built-in “run docker system prune -af after each act workflow” option.

The simplest automation is to wrap act yourself, for example:

#!/usr/bin/env bash
set +e
act "$@"
status=$?
docker system prune -af
exit "$status"

The important caveat is that docker system prune -af is a global Docker cleanup. It can remove unused Docker resources from other projects too, not only resources created by this act run.

So the safer recommendation is:

• use a wrapper script if you really want automatic cleanup;
• avoid global prune if you share the Docker daemon with other work;
• prefer a future scoped cleanup mechanism if act adds one, e.g. labels on act-created Docker resources and pruning only those labels.

Since this answered the original question, it may be useful to mark the answer as accepted so future readers can find the resolution more easily.