Jekyll-feed combined feeds

I wanted to add support for an atom feed for this site, but my use of Jekyll is a bit unconventional and so jekyll-feed couldn’t quite do what I needed. I needed a way to generate a single feed from multiple collections. This was requested by a few people on GitHub but it doesn’t seem to have been implemented so I thought I would have a go.

You can find my fork with this feature at https://forgejo.zacjw.com/zac/jekyll-feed

Use of the new feature is pretty simple. Here’s an excerpt of this site’s _config.yml:

feed:
  combined_feeds:
    all_posts:
      collections:
        blog:
        projects:
          except:
            is_top_level: true

This also shows off that I added a filtering feature to the combined feeds since I needed a way to exclude certain project posts from the feed. I’ve not tried upstreaming this yet (I feel like the filtering feature is pretty niche so they might not accept it), but maybe I’ll do that at some point.