Problem Description

In GitHub, after specifying a custom domain in Settings > Pages, the CNAME file gets deleted every time VuePress is deployed automatically using GitHub Actions.

Solution

According to VuePress documentation, there's a tip that says:

TIP

When you use a Custom Domain name, you MUST add the CNAME file into /docs/.vuepress/public folder (Create the folder if it isn't there). Otherwise, your CNAME file will always be removed with each deploy and never work.

So the correct approach is to create a file named CNAME inside the /docs/.vuepress/public directory. The content of the file should be your custom domain:

mycustomdomain.com

This way, when VuePress builds the site, the file will be copied to the /docs/.vuepress/dist directory, and GitHub will not delete the original CNAME during deployment.

Additionally, add the following CNAME setting in your .github/workflows/deploy.yml file:

# See the workflow documentation for more info
      # @see https://github.com/crazy-max/ghaction-github-pages
      - name: Deploy to GitHub Pages
        uses: crazy-max/ghaction-github-pages@v4
        with:
          # Deploy to the gh-pages branch
          target_branch: gh-pages
          # VuePress default output directory
          build_dir: docs/.vuepress/dist
        env:
          # @see https://docs.github.com/en/actions/reference/authentication-in-a-workflow#about-the-github_token-secret
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          CNAME: https://mycustomdomain.com/

All done!