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thecrumb.com - Under the hood: Docker

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In the past I’ve had Pelican installed locally. This isn’t difficult but when I occasionally reformat my maching setting things up again is sort of a pain. It’s 2019 - how about we use a container!

While there were some Pelican images on Docker hub the install is so simple I just created my own:

FROM bitnami/minideb:latest

# Update & add prerequisites
RUN install_packages \
  python \
  python-dev \
  python-pip \
  python-setuptools \
  git \ 
  build-essential

ADD requirements.txt requirements.txt
RUN pip install --upgrade pip 
RUN pip install -r requirements.txt

WORKDIR /project

CMD ["make", "devserver"]

Lets step through this. First we need an image. I used this ‘minideb’ from Bitnami. It’s not as small as Alpine but it’s a familiar Debian system so I don’t have to worry about weird package managers, etc. And since this is local I really don’t care about image size anyway.

This minideb also has a ‘install_packages’ command built in which does a few nice things for you automatically:

  • Install the named packages, skipping prompts etc.
  • Clean up the apt metadata afterwards to keep the image small.
  • Retrying if apt fails.

Nice!

So we install all the requirements for running Pelican: Python, Git and some build tools.

Then we copy over a pip requirements file from my blog files and use pip to actually install Pelican and a few other things:

beautifulsoup4
cssmin
markdown
pelican
webassets

Next we define a directory in the image and run the Pelican command ‘make devserver’ which will serve my local files and rebuild things if I change a file.

Now we need to run this container.

I can never remember all the port and volume flags so I just created a simple script:

 #!/bin/bash 

 wd=$(pwd)
 docker rm -f thecrumb/pelican
 docker run \
 --rm \
 --name pelicanbox \
 -p 80:8000 \
 -v $wd/git/.gitconfig:/root/.gitconfig \
 -v $wd/ssh:/root/.ssh \
 -v ~/www/thecrumb:/project \
 -it thecrumb/pelican

So this will run Docker, set the ports, copy over some git and ssh things and finally create a volume mapped to my local files where I have my actual blog content - www/thecrumb. Now Pelican can build with my content.

Running that will serve up my blog locally at localhost. And I can edit files and my content will be regenerated.

jim@jim:/mnt/Files/www/thecrumb$ ./start-docker.sh 
pelican -lr content -o output -s pelicanconf.py 
-> Modified: content, settings, theme, [static]images. re-generating...

So now we have Pelican containerized. I store the dockerfile and start-docker.sh in the root of my blog so it’s under version control.

Now I can craft a blog post and view it locally.

In the next post I’ll go over how I get my files to the server via GitLab CI.