I'm still using Docker Swarm in production, and it's great! You write Compose files (which are succinct compared with k8s), with an optional smattering of just a few extra functions (such as for configs and secrets). You can easily specify how many replicas you want, constrain them to certain nodes with labels, use health checks for auto restarts etc.

If you can write Compose files, you can do Docker Swarm - it's so wonderfully simple!

I am increasingly nervous about Swarm support staying in Docker though, and plan to at least look into Nomad for my next project.