[jeltz]

Every great journey must have an end. As far as I understand Cirrus CI was struggling due to Github Actions eating their market. Cirrus CI was in my opinion much better than Github Actions but it is hard to compete with a bundled solution.

[esafak]

What was good about it? It looks pretty ordinary to me: https://cirrus-ci.org/features/

[anarazel]

Ability to trivially use custom VM images was quite nice. The amount of CI time spent installing dependencies or copying a cache of installed stuff is nontrivial. Particularly for Windows the time difference is often very substantial. But even for plain Linux, there's no point in apt-get update && apt-get install the same set of things in every run (when using containers, cirrus could build them in-demand too, with little notational overhead).

Defaulting to throw-away-VMs for everything is also the right choice for something where the threat model includes attackers submitting patches/PRs. I'll never understand why folks were ok with just container separation for that (and often have no separation in runners).

[a1o]

It gives a better docker based experience and it also has measurements of memory and cpu usage to help you dimension things quickly.

[jeltz]

Much better UX for viewing logs, more supported platforms. Github Actions in particular is also very unstable.