In my previous post I told about switching from Fedora to CentOS. Most of the software was pretty easy to set up, and if something was missing, it was quite convenient to just to ./configure; make; make install. But some things were just not that easy. For example the generation of this web site.

Jekyll is written on Ruby. Ok, so I installed ruby, but the version was too old! So no luck there. I didn’t feel like compiling the Ruby from sources, so I did something else: I created by blogging environment as Docker container.

Idea is this: I maintain the web site repository on the host system, and edit the source files there with Emacs. Then I have the Jekyll dev site running in the container, and when I’m happy with my blog post, I just push the sources from the host system and close down the container.

This is my Dockerfile:

FROM debian

RUN apt-get update && \
    apt-get -y install \
    	    ruby \
	    ruby-dev \
	    build-essential \
	    rsync \
	    python \
	    ssh \
	    git \

RUN groupadd jarkko -g 1000
RUN useradd -rm -d /home/jarkko -s /bin/bash -g jarkko -u 1000 jarkko

USER jarkko
WORKDIR /home/jarkko

RUN gem install --user bundle jekyll
RUN echo 'export PATH=/home/jarkko/.gem/ruby/2.5.0/bin:$PATH' \
            > /home/jarkko/.bashrc
VOLUME /home/jarkko/.gem

RUN mkdir website
WORKDIR /home/jarkko/website

I run the container like this:

docker run --rm --name blog -p 4000:4000 \
    -v blog_gems:/home/jarkko/.gem  \
    -v /home/jarkko/dev/bitbucket/website:/home/jarkko/website:Z \
    -u jarkko -it debian-blog bash

Some notes:

  • There’s a Docker volume for .gem, because I don’t want to re-install all the gems every time I start the container
  • The repository is shared with SELinux flag (:Z) because I run the Docker with SELinux
  • I run bash interactively, so I can do things like this:
jarkko@26a82303f5d9:~/website$ bundle exec jekyll serve --host=
Configuration file: /home/jarkko/website/_config.yml
            Source: /home/jarkko/website
       Destination: /home/jarkko/website/_site
 Incremental build: disabled. Enable with --incremental
                    done in 2.687 seconds.
 Auto-regeneration: enabled for '/home/jarkko/website'
    Server address:
  Server running... press ctrl-c to stop.
      Regenerating: 2 file(s) changed at 2019-08-11 15:55:11
                    ...done in 2.404816922 seconds.

Now when I edit my blog post draft in the Emacs, Jekyll dev environment running inside the container works just like it would running on the host.