Fiddling with Fig

Although we are currently only using two containers, the command to boot both containers is quite long. Before introducing the third data only container, I want to simplify starting and stopping our containers. Fig is a tool to simplify this, with Fig you can describe your containers boot parameters and depedencies inside a configuration file using yaml syntax.

Fig can be installed using the following command

$ sudo pip install fig

or download it from GitHub. While writing this post Fig is being renamed by the docker team to Docker compose or Compose for short.

Looking at our current containers, the first container that contains PostgreSQL is started using the following command line

$ sudo docker run --name postgres -e POSTGRES_PASSWORD=mysecretpwd -e POSTGRES_USER=ghostdb 
  -v /home/kalkie/postgres:/var/lib/postgresql/data -d postgres

while the second container that contains Ghost is started using the following command line

$ sudo docker run -d -p 80:2368 -v /home/kalkie/ghostdata:/ghost-override --link postgres:postgres dockerfile/ghost

This is how the fig.yml configuration file looks like to boot both container

ghost:
  image: dockerfile/ghost
  links:
   - postgres
  ports:
   - "80:2368"
  volumes:
   - /home/kalkie/ghostdata:/ghost-override

postgres:
  image: postgres
  environment:
    POSTGRES_PASSWORD: mysecretpwd
    POSTGRES_USER: ghostdb
  volumes:
   - /home/kalkie/postgres:/var/lib/postgresql/data

The file is divided into two sections, ghost and postgres representing both containers.

ghost: The name of the instance of the container
image: The name of the docker image
links: To which container should this container link
ports: Defines the port mapping
volumes: Defines the volume mapping
postgres: The name of the other container
image: The name of the docker image
environment: Defines the environment variables to set
volumes: Defines the volume mapping

Basically the fig.yml contains all the parameters of the command line but structured differently.

Both containers can now be started using the command

$ sudo fig up

or in deamon mode

$ sudo fig up -d

which is a lot simpler then using the docker command line.

Next, we will be looking at centralizing the data of the Ghost and the PostgreSQL container using a data only container so that creating backups becomes easier.

SimpleTechture

IT Architecture should be Simple

Fiddling with Fig