What is Fig ?

Fig http://fig.sh is a simple orchestration tool for managing multiple docker containers, now the company is acquired by docker.

Simple you write configuration in fig.yml file (source from https://github.com/larrycai/codingwithme-ansible/blob/master/fig.yml like

ansible:
  image: dockerfile/ansible
  volumes: 
   - /home/docker/codingwithme-ansible:/data
  links: 
   - haproxy
   - web1
   - web2
   - database
haproxy:
  image: larrycai/ubuntu-sshd
web1:
  image: larrycai/ubuntu-sshd
web2:
  image: larrycai/ubuntu-sshd
database:
  image: larrycai/ubuntu-sshd

Then execute fig run ansible, it will launch the docker container as you defined: sample above is to start 5 docker containers and enter into ansible container for testing.

Learn fig more in http://blog.docker.com/2014/08/getting-started-with-orchestration-using-fig

Problem for running environment

Before using the fig, you mostly need to install it, while if you check http://www.fig.sh/install.html, you will notice it only support OS X (with boot2docker 1.3) and other Linux system, you can’t install it in Windows (boot2docker env).

Also if you start to play with CoreOS, you will find it is difficult to install it as well, in official document, it recommends to use fleet (coreos tool) instead to manage docker service. Then you need to run fig2coreos, it is not so sweat for small things.

How can we solve it ?

TLDR;

docker run larrycai/fig

Using docker in docker for fig

The solution is not difficult actually, we can simple to have a fig container to run docker inside, surely it needs docker inside docker as well.

See Dockerfile

## docker run -v /var/run/docker.sock:/docker.sock -v <figapp>:/app larrycai/fig

FROM ubuntu:latest
MAINTAINER Larry Cai "larry.caiyu@gmail.com"
ENV REFREST_AT 20141015

RUN apt-get update && apt-get install -y curl make

RUN \
    curl -L https://get.docker.io/builds/Linux/x86_64/docker-latest -o /usr/local/bin/docker  && \
    chmod +x /usr/local/bin/docker && \
    
    # see http://www.fig.sh/install.html 
    curl -L https://github.com/docker/fig/releases/download/1.0.0/fig-`uname -s`-`uname -m`  -o /usr/local/bin/fig && \
    chmod +x /usr/local/bin/fig 
    
ENV DOCKER_HOST unix:///docker.sock

WORKDIR /app

# set initial command

ENTRYPOINT ["/usr/local/bin/fig"]
CMD ["-v"]

It will install latest docker inside, and also follow the fig installation to install 1.0.0 version as well

How to use it ?

As normally docker container, run it directly to see the fig help (which is default)

docker@boot2docker:~$ docker run larrycai/fig
Punctual, lightweight development environments using Docker.

Usage:
  fig [options] [COMMAND] [ARGS...]
  fig -h|--help
....

Now if I clone my codingwithme-ansible sample code locally into /home/docker (see fig.yml sample above), then I can run

docker@boot2docker:~/codingwithme-ansible$ docker run -it \
 -v /var/run/docker.sock:/docker.sock \
 -v /home/docker/codingwithme-ansible:/app \
 larrycai/fig run ansible

Then it will start web stack containers (haproxy/web/database) at once ( download needed docker image for first time) and run into ansible container

-v /var/run/docker.sock:/docker.sock is used to pass the docker daemon socket into docker container so docker inside can communicate outside to control docker.
-v /home/docker/codingwithme-ansible:/app is to share the host folder inside.

Remind

Just remind one thing, since those docker commands are run in host machine, please specify the absolute path in volumes, don’t use .

  volumes: 
   - /home/docker/codingwithme-ansible:/data

This is the only limitation for using fig docker container, I guess.

Summary

Now using fig docker image, you don’t need to install fig manually, this is core value for docker. And it works in Windows (boot2docker 1.3+)/CoreOS as well.

Enjoy.