I'm jumping from a local docker-compose building, to a production environment, in which I have 4 vps. The first (the manager) is the one with the least resources. The other 3 have the same and are biggers (the workers). I decided to use docker swarm, to manage these infrastructure. My doubt is, Should I be concerned about which host x container is running on? Or this is a bad concept of mine? I mean, is the docker swarm meant for me to abstract from the underlying nodes, and create the services and containers trusting that docker will manage the resources successfully?
Answer is... both! The goal is to let Docker Swarm manage things for you as much as possible, but also add constraints in order for your application to deploy on the hardware that matches best its requirements.
For example, if you have a reverse proxy and machine learning models, you might want to deploy your reverse proxy on a CPU optimized server, and your machine learning models on a memory optimized instance.
You need to label your nodes properly, and then add constraints so that services are only deployed to the nodes that match your labels. For example in the example above you could add 2 labels: reverse-proxy and ml.
I am explaining how to do this more precisely in this article in case you're interested: https://juliensalinas.com/en/container-orchestration-docker-swarm-nlpcloud/