In 2011 the hotness was "puppet", coming from cfengine, so I spent time learning puppet, it's quirks and desired ways of working.
Then I "grew" into using Chef instead, being similar but very different.
Then I went to a company that had to start fresh, in a predominantly Windows environment, I tried "round-hole, square-peg"-ing chef into the situation. That failed and I found myself working with SaltStack (as its windows story, while slow, was workable).
Then Ansible became the defacto standard. For a long time I felt like I had stalled as an engineer because I did not pick up Ansible.
I returned to industry never having acquired those skills, but now almost nobody is using Ansible, it's all kubernetes, helm and if you're really new: NIX.
For 6 years I used SaltStack and felt like I wasn't growing, because the treadmill kept going without me. Turns out, I never needed it, I could just jump on the train whenever I needed.
See also: Linux administration pre vs post systemd. (and linux administration in general since everything is kubernetes based nowadays).
It probably depends on the place, I know projects that use Ansible, I know some that use Docker Swarm, I know some that also are either all in on Kubernetes or, quite the opposite, run in a VM or on bare metal somewhere.
Honestly, sometimes Ansible or even Docker Swarm or something like Docker Compose are nice to use because they’re a better fit for a problem than one of the “mainstream” solutions (e.g. Kubernetes is great but has complexity to manage, unless you can pay someone else to provide a cluster for you).
Sadly, none of that matters when you’re looking for a job and the latest mainstream technologies reign supreme then.
