This action checks the syntax of your html files in the path that you provide.
It used html5validator and a docker image that I build from it found here.

For a help getting started check out the wiki.

The root path of the files you want to check.

The path to the config file.

Additional arguments to pass to html5validator.

Format for logging. Supported values: json, xml, gnu, text.

Log level to use. Supported values: DEBUG, INFO, WARNING. Default: Warning.

If to check css. Supported values: true, false. Default: false.

The exit code of the validation.

      uses: Cyb3r-Jak3/[email protected]
      with:
        root: tests/valid/

There is a log file that is automatically created. To retrieve it you need to use Github's upload artifact action after the validator action.

    - uses: actions/upload-artifact@v2
      with:
        name: log
        path: log.log