Styjun

I have a Rails app I am deploying in Docker containers via Ansible. My app includes three containers so far:

• A Docker volume container (created with docker volume create --name dbdata)


• A Postgres container (with volumes_from dbdata)


• The Rails app container (which links to the postgres container)

My deploy playbook is working, but I had to run the docker volume create command on the server via SSH. I'd love to do that via Ansible, so I could deploy a fresh instance of the app onto an empty container.

Is there a way to run docker volume create via Ansible, or is there some other way to do it? I checked the docs for the Ansible Docker module but it doesn't look like they support volume create yet. Unless I'm missing something?

Here's one option, using the command module.

- hosts: localhost
 tasks:
 - name: check if myvolume exists
 command: docker volume inspect myvolume
 register: myvolume_exists
 failed_when: false

 - name: create myvolume
 command: docker volume create --name myvolume
 when: myvolume_exists|failed

We first check if the volume exists by using docker volume inspect. We save the result of that task in the variable myvolume_exists, and then we only create the volume if the inspect task failed.

You can now use -v argument to create named volumes, from man page of docker run:

If you supply a name, Docker creates a named volume by that name.

 - name: Run mariadb
 docker_container:
 name: mariadb-container
 image: mariadb
 env:
 MYSQL_ROOT_PASSWORD: "secret-password"
 MYSQL_DATABASE: "db"
 MYSQL_USER: "user"
 MYSQL_PASSWORD: "password"
 ports:
 - "3306:3306"
 volumes:
 - mariadb-data:/var/lib/mysql

mariadb-data is a named volume which was automatically created by docker:

$ docker volume inspect mariadb-data
[
 
 "Name": "mariadb-data",
 "Driver": "local",
 "Mountpoint": "/var/lib/docker/volumes/mariadb-data/_data",
 "Labels": null,
 "Scope": "local"
 
]

You can manage docker volumes with Ansible's own docker_volume module. New in version 2.4.