Trying out Forestry.io for page editing (Update: NetlifyCMS)
Interesting, at least
I think the basic free model works for what I need. I'm not even using it for any compilation or building; it's just committing changes made back to the GitLab repo, and that is doing it's own build/deploy as part of GitLab Pages. Forestry.io looks to support plenty of static site generators, and has extra features for Jekyll menus.
The editor is pretty decent, although a side-by-side markdown/preview would be nice, and I don't need to see the front matter all the time once it has been entered.
More advanced edits, and layout/style changes and such would all still need to be done in GitLab itself, but for basic blogging and what-not, looks like this will do fine.
Update (2017-Aug-15):
Looks like this is pretty easy, and able to update from anywhere. I was looking at something like Dillinger.io, but there is some work needed to get it to support GitLab
Update (2020-Aug-04):
Now I'm updating/editing the pages and posts using NetlifyCMS. Full post to come about that soon!