Lightweight Docker experience on OSX

At the moment Docker runs only on Linux. On OSX you have to setup a VM with Linux installed on it in order to use it. The most popular approach is by using Vagrant but this VirtualBox abstraction seems heavy. There is another, more lightweight way of interacting with a VM on OSX using great boot2docker project. It spins up a small Linux distribution (called Tiny Core Linux) which runs from RAM, weights around 24 MB and boots in 5-6 seconds.

In this article I’ll guide through all necessary steps to create more lightweight Docker experience on OSX.

Install Docker client build for OSX

curl -o docker http://get.docker.io/builds/Darwin/x86_64/docker-latest
chmod +x ./docker
mv docker ~/bin
export DOCKER_HOST=localhost

docker version
Client version: 0.7.6
Go version (client): go1.2
Git commit (client): bc3b2ec
2014/02/05 16:19:18 dial unix /var/run/docker.sock: no such file or directory

We are getting an error because there is no Docker daemon listening on the socket. We will fix that in a moment by using the daemon that sits on the VM.

Install boot2docker

curl https://raw.github.com/steeve/boot2docker/master/boot2docker > boot2docker
chmod a+x boot2docker
mv boot2docker ~/bin/boot2docker

Initialize the VM and then start it

boot2docker init
[2014-02-01 16:22:12] Creating VM boot2docker-vm
...

boot2docker up
[2014-02-01 16:22:52] Starting boot2docker-vm...
[2014-02-01 16:23:12] Started.

Check if you can ssh into it (password is tcuser)

boot2docker ssh

Export DOCKER_HOST as localhost so local Docker OSX client can communicate with the socket on the VM

export DOCKER_HOST=localhost

Run docker version to check if it works.

docker version
Client version: 0.7.6
Go version (client): go1.2
Git commit (client): bc3b2ec
Server version: 0.7.6
Git commit (server): bc3b2ec
Go version (server): go1.2

Let’s pull our first image and try to run it

docker pull zaiste/postgresql
Pulling repository zaiste/postgresql
…

docker run -d zaiste/postgresql
docker ps
CONTAINER ID        IMAGE                      COMMAND                CREATED             STATUS              PORTS                    NAMES
daffafef1a96        zaiste/postgresql:latest   /bin/su postgres -c    14 minutes ago      Up About a minute   0.0.0.0:5432/tcp   insane_turing

You can also build a Docker client yourself. For that you will need Go installed on your system. For OSX the easiest way is to get it using Homebrew.

brew install go

go get -v github.com/dotcloud/docker/docker
...
mv tmp/bin/docker ~/bin/

Hopefully, those steps will make your interactions with Docker on OSX simpler and more productive.