> Not trying to start a Docker vs. Ansible flame war
Don't worry, they serve very different purposes. You already probably know but Docker is for running applications in isolation, while Ansible is for provisioning and configuring hosts. For instance, you won't use Docker to harden sshd on your hosts but Ansible.
After figuring out Ansible work I started using it to manage several personal VPS machines and the various boxes at home.
I just used the Ansible docs, which are pretty good.
Just start a simple project with Ansible and have a look at the repositories using Ansible to install Docker and deploy containers on your host afterwards.
You may want to put some effort (not that much) into managing your credentials with Ansible Vault[0] and you can try your playbooks e.g. on a Vagrant Machine[1] before applying them to a real host.
Any tutorial will do for the beginning but you should always notice what version of Ansible you are using (vs. the one used in the tutorial) as features change and also there have been some changes to the syntax to improve readability of your playbooks.
How is docker container, running a process as unprivileged user with reduced capabilities security disaster? With Kubernetes you can even have network policy or service mesh with mTLS. Compare it to bunch of bare processes running on the same machine, lots of services listening on localhost, difficult updates due to different dependency version requirements by different software, requiring you do the manual, painful update only once a year. It may look bad at first, but container can be far more secure that common non-container environments. It's always matter of configuration and maintenance.
Don't worry, they serve very different purposes. You already probably know but Docker is for running applications in isolation, while Ansible is for provisioning and configuring hosts. For instance, you won't use Docker to harden sshd on your hosts but Ansible.