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Docker - 3 Quick Tips

Docker I'm reading and testing a bit about this new tool (Docker), and after some time I discovered some tips that I wanted to share with you guys.


1 - Check out other containers filesystems

Maybe for what you plan on installing inside a container, the default filesystem that Docker uses (AUFS), ins't the best choice. A pretty good example is a MySQL DB image, that has a problem already documented. But don't be alarmed, there is a workaround for this! You just need to change your Docker filesystem to Device Mapper.

2 - Debugging Containers With Nsenter

If you want to debug your containers, and don't feel very well installing a SSHD inside each container just to navigate inside it, then you should use Nsenter. This allow you to get a prompt inside your container that has a process initialized, and it doesn't hurt the Docker principle (one concern per container).

You can read more about this in here: If you run SSHD in your Docker containers, you're doing it wrong!

3 - Test things with Vagrant!

Had problem installing Docker in your machine? Or maybe you just want to test this new tool in a clean environment? That's easy, since the guys from Phusion created a base Vagrant image that has it's a kernel ready to install docker.

So all you have to do is

{lang="shell"} $ vagrant init phusion/ubuntu-12.04-amd64

And you'll have a Vagrantfile ready to go.

More info on this in here: Docker-friendly Vagrant base boxes

That's all, and have fun playing with Docker!