Rocked

A thin wrapper to manage Docker containers. It just generates command line arguments to be passed to the docker client, based on the chosen command and loading the container configuration data from a manifest file, written in YAML format. So, instead of typing docker run --rm -t -i -e DATABASE_NAME=django_app -e DJANGO_SECRET_KEY --link db_postgres:db -v /home/myhro/projects/django-example:/app python-baseimage python manage.py shell every time you want to access the Django Shell, you would just type rocked run web.yml python manage.py shell, which produces the same result.

Dependencies

Its only dependencies are docopt and PyYAML, which can be installed either in a virtualenv or in a system-wide installation using pip:

pip install -r requirements.txt

Installation

As Rocked is not available on PyPI yet, you have to clone this repository and add its executable to anywhere on your $PATH, e.g.:

sudo git clone https://github.com/myhro/rocked.git /usr/local/lib/rocked
sudo ln -s /usr/local/lib/rocked/rocked.py /usr/local/bin/rocked

Then you can just use the rocked command:

[myhro@wheezy:~]$ rocked -h
Rocked, a thin wrapper to manage Docker containers.

Usage:
    rocked build [--no-cache] <file.yml>
    rocked kill <file.yml>
    rocked logs [-f] <file.yml>
    rocked run [--root] <file.yml> [--] [<command>...]
    rocked restart <file.yml>
    rocked start <file.yml>
    rocked status <file.yml>
    rocked stop <file.yml>
    rocked -h | --help

Options:
    -h --help   Show this screen.

Manifest

The manifest file is written in YAML format. This is the list of supported and required keys:

Key	Type	Description	Required
build	string	Directory where a Dockerfile to be built is located	no
command	string	Command to be executed on the container	no
environment	list	List of environment variables to be set	no
image	string	Name of the image	yes
links	list	List of other containers to be linked	no
name	string	Name of the container	yes
ports	list	List of ports to be published	no
user	string	User which will run commands instead of root	no
volumes	list	List of volumes to be mounted	no

Examples

Database container

Create a container based on the postgres image (tag 9.3), named db_postgres and mount a persistent volume to store PostgresSQL's data:

image: "postgres:9.3"
name: "db_postgres"
volumes:
    - "/var/lib/postgresql/docker:/var/lib/postgresql/data"

Start the container daemon:

[myhro@wheezy:~]$ rocked start db.yml

Web application container

Based on this Dockerfile...

RUN apt-get update
RUN apt-get install -y build-essential libpq-dev python-dev python-pip
ADD . /app
WORKDIR /app
RUN pip install -r requirements.txt

... and this manifest ...

image: "python-baseimage"
build: "."
command: "gunicorn -b 0.0.0.0:8000 django_app.wsgi"
environment:
    - "DATABASE_NAME=django_app"
    - "DJANGO_SECRET_KEY"
name: "web_djangoapp"
links:
    - "db_postgres:db"
ports:
    - "${GUNICORN_PORT}:8000"
volumes:
    - "${PROJECT_ROOT}:/app"

... build an image prepared to run a Django web application, then serve it using Gunicorn:

[myhro@wheezy:~]$ rocked build web.yml
Step 0 : FROM ubuntu:trusty
 ---> e54ca5efa2e9
(...)
Step 5 : RUN pip install -r requirements.txt
 ---> 6c13fc4515aa
Successfully built 8d2d8f4be123
[myhro@wheezy:~]$ rocked start web.yml

Note: environment variables, like ${GUNICORN_PORT} and ${PROJECT_ROOT} will be parsed when reading the manifest.

A note about the rocked run command

With the rocked run command, it's possible to run arbitrary commands in a temporary container, using the image specified on the manifest, like:

[myhro@wheezy:~]$ rocked run web.yml python manage.py migrate

But if the command contains dashes, it needs to be escaped with --, e.g.:

[myhro@wheezy:~]$ rocked run web.yml -- wc -l /etc/passwd

Otherwise it would be interpreted as an argument of Rocked itself.

License

MIT License