How do I create docker image from an existing CentOS?

Question

I am new to docker.io and not sure if this is beyond the scope of docker. I have an existing CentOS 6.5 system. I am trying to figure out how to create a docker image from a CentOS Linux system I already have running. I would like to basically clone this existing system; so I can port it to another cloud provider. I was able to create a docker image from a base CentOS image but I want to basically clone my existing system and use docker.io going forward.

Am I stuck with creating a base CentOS from scratch and configure it for docker from there? This might be more of a VirtualBox/Vagrant thing, but am interested in docker.io.

Looks like I need to start with base CentOS and create a Dockerfile with all the addons I need... Think I'm getting there now....

Answer 1

Cloning a system that is up and running is certainly not what Docker is intended for. Instead, Docker is meant to develop your OS and server installation together with the app or service, making DevOps even more DevOpsy. By starting with a clean CentOS image, you will be sure to install only what you need for the service, and have everything under control. You actually don't want all the other stuff that might produce incompatibilities. So, the answer here is that you definitely should approach the problem here the other way around.