Workflow not running for Docker build?

I’ve added a workflow based on https://github.com/actions/starter-workflows/blob/master/ci/docker-image.yml but for some reason the build is failing, claiming that the syntax is invalid. It looks fine to me?

For a failing build, see https://github.com/gradescope/pdfium/pull/4/checks?check_run_id=416250917

Thanks!

I checked your workflow yml, it is in right syntax. Which language do you use? 

Can you try on: push without [] ? Will the error disappear?