Debugging GitHub Workflow actions

Recently the publish workflow action failed with an obscure error. Attempts to replicate the exact workflow in a local Ubuntu Vagrant machine failed, probably due to slightly different setups. Replication of the GitHub actions locally is not possible.

That leaves debugging the action as it runs.

Info:

• https://github.community/t/debugging-github-actions-locally-or-ssh-to-workspace/16974
• https://github.com/marketplace/actions/debugging-with-tmate

Preparation:

• add the installation of tmate to the github workflow just before the problematic step
• if necessary change the scheduling frequency to something easier to work with
• commit and push the changes
• commit and push another change in a file not in the .github directory to trigger the new workflow (and activate the new schedule)

Debug:

• wait for the build to run
• open the action and check the steps that are executed
• when tmate executes it will print a command in the console like ssh <random number>.tmate.io
• copy the command and paste and execute it in a Terminal window
• you are now ssh-ed into the running build and you can debug the problem

Final steps:

• remove the tmate step
• fix the schedule
• commit and push the workflow file
• fix the problem
• commit and push the problem to activate the new version of the workflow (and fix the problem)