I am new to jekyll, but I have built a site that is live, hosted on netlify.
Now I would like to use netlify deploy previews so I can test some changes without modifying the main public site. Such deploy previews are published at an url which I cannot predict. The url is available in an environment variable.
I can’t figure out how to get this url into my build. It needs to be in a _config.yml file, but I don’t know it in advance. I would like to override the site var in _config.yml on the jekyll build command line, but that doesn’t seem to be possible.