Atomic host is a great technology for containerized applications. I like it especially on bare metal machines. In this post I will describe how to setup a simple Do-It-Yourself cluster consisting of three netbooted machines running docker over flannel. Flannel provides a NAT-less private network overlay. Through that network, application containers can easily reach any other containers within the cluster regardless of which machine they run on.
We use three machines called a1, a2, and a3. Let’s designate static IP addresses to them.
- a1: 192.168.99.51
- a2: 192.168.99.52
- a3: 192.168.99.53
We install atomic host OS on these machines via netboot from another host. Let’s call that host boothost. It holds all installation and configuration files. We set up an unattended installation and configuration using kickstart and cloud-init.