site.baseurl contains no value in circleCI

[jduss4]

Actual Behavior

Throughout the blog, people use {{site.baseurl}} in front of image paths. However, the value of site.baseurl is not set in _config.yml. Recently, during a CircleCI run, html-proofer reported 4 broken links. These links were broken because site.baseurl is empty.

(image alt: four errors from _site/2022/07/20/senior-executives-pt1/index.html with links similar to /2022/07/20/senior-executives-pt2)

Expected Behavior

The expected behavior is for html-proofer to be able to validate internal URLs in circleCI's environment while avoiding breaking functionality locally and in production.

Ideally, we would also document some of the additional config files, such as _config-blog.yml which have differing site.baseurl settings.

Steps to reproduce the behavior

• [ ] Prepend an internal link to another page of the 18F website with {{site.baseurl}}
• [ ] Make a PR and confirm the html-proofer step of CircleCI fails

This issue is done when

• [ ] Either {{site.baseurl}} is set appropriately or html-proofer running in a CICircle environment can check internal links through other means (perhaps a CLI flag or calling a different script from .circleci/config.yml )
• [ ] Internal links continue to work locally (both in docker and without) and in production
• [ ] Documentation has been added explaining how to use site.baseurl