Docker is a slick container based virtualization platform that allows you to run “images,” with minimal overhead. There are many different images available, from full blown OS’s, such as Ubuntu or CentOS, to web apps like WordPress or Ghost. The possibilities are endless, and because resource usage is minimal, you can really do a lot with little resources. You can install docker on all of the major linux distributions, as well as windows. I works fine in a virtual machine, or VPS. I will be installing Docker on a CentOS 7 VM, running on an ESXi hypervisor.
Lets Get Started
I’m assuming you already have your operating system installed, you are sitting at a command prompt. Installation and configuration is very easy on CentOS 7. By default, CentOS uses firewalld. Docker and firewalld do not get along nicely. Docker creates iptables rules directly for access to running containers, and if firewalld is refreshed or restarted, all of the iptables rules docker initiated get wiped by firewalld. So, we will disable firewalld and install the classic iptables functionality. Here are the steps involved:
- Install Docker
- Disable firewalld
- Install iptables configuration scripts
- Download Ghost Docker image and run
First, we will go ahead and install Docker. To do this only requires a single, simple command.
# sudo yum install docker
Let’s set up Docker to start at boot time.
# sudo chkconfig docker on
There will be a handful of dependencies, nothing out of the ordinary. If you are already running as root, you can omit the sudo. Next, we need to get firewalld stopped, removed, and iptables configuration scripts installed.