act Is it possible to validate workflows with act, without running them?

Act version

act version 0.2.75

Feature description

Hi there!

First of all, congrats for putting together this awesome tool!

I would like to be able to validate the workflows (for syntax errors) in CI/CD. Would act allow this? I checked act --help but I could not see any flag for validation or such.

thanks!!

Mar 27 '25 06:03 mm-chia

I would like to be able to validate the workflows (for syntax errors) in CI/CD. Would act allow this?

You can use dry run mode of act or use https://github.com/rhysd/actionlint

Mar 27 '25 09:03 panekj

I think --list is better, than dryrun due to open bugs and concerning test coverage in act.

If you mean the basic schema validation I added last year.

Mar 27 '25 12:03 ChristopherHX

Thanks for your input!

I've tried act --list but the command lists the workflows, without doing any validation on them (or so it seems). I broke the yaml format, I put wrong values for events.. but act is still happy with it :) act --dryrun also ignores any issues with event names, and other things, it doesn't seem to be doing much validation either - it happily runs with broken schema :)

I need a tool that will validate the github workflows for syntax/schema, so we can catch any issues at pull request time. Do you know if any official tool from Github, for this purpose? I've spent quite a bit of time searching, but I couldn't find one..

I did try actionlint, but it has some issues (false positives), so I can't really use it as it is now.. Their repository has over 100 issues opened, but I'm not sure how much activity on it .. I also tried github-workflow-validator, but this one has a long standing issue with glob validation, so that's also a deal breaker :(

Mar 27 '25 15:03 mm-chia

I broke the yaml format, I put wrong values for events.. but act is still happy with it :)

To comply with the GitHub Action spec we cannot use the strict schema

Our source of the schema (The official GitHub Actions Extension) has errors and would reject valid workflows in strict mode re https://github.com/nektos/act/pull/2524

If the previous v0.2.74 would report your change as error before execution, then I could create an --validate --strict flag that might do just what you want using the disabled strict validation

Mar 27 '25 17:03 ChristopherHX

Yes, that command will probably do the trick, if implemented. Thanks for the great feedback!

Mar 28 '25 06:03 mm-chia