05 Dec 2014

GitHub pages and Docker

You need to install Ruby, Jekyll and a lot of Ruby gems to test your blog on your machine. With Docker, you can eliminate these installations and run Jekyll in a fancy Docker container. I think, this method is far more simple (and elegant) than the manual way to install all the gems Jekyll needs.

Requirements:

1. a Linux machine with Docker installed,
2. a Docker image containing all Ruby gems installed,
3. fig installed on your host.

I found a great Docker image but I needed some more gems to be installed, so I extended it with some instructions:

FROM grahamc/jekyll

COPY Gemfile /tmp/
COPY Gemfile.lock /tmp/
RUN cd /tmp && bundle install

ENTRYPOINT ["jekyll"]

The base image creates a mount point at /src, so I can mount the source code of my site into the container. Accoring to the original author, we can start the container with the following command:

$ sudo docker run -d -v "$PWD:/src" -p 4000:4000 grahamc/jekyll serve

It’s a good feature, but we can go deeper and use fig to make it more comfortable.

Docker’s fig can describe your containers in a YAML file, so you don’t have to specify their parameters on every run. My fig.yml looks like this:

jekyll:
    build: .
    volumes:
        - .:/src
    ports:
        - "4000:4000"
    command: serve --watch

It says, build a Docker image from my Dockerfile, mount the current directory as /src into the container and create a port binding between the host and the container.

You have to bootstrap it first:

$ fig run jekyll build

Now, you can start your own Jekyll server with the following command:

$ fig up

And that’s all :)

References

• Fast, isolated development environments using Docker
• Dockerfile Reference

Till next time,
Tibor Benke at 23:00