Using Jekyll docker image to build your site

Update: I no longer use Jekyll. I use Hugo now.

I usa Jekyll to build this site. Recently, I switched to Manjaro Linux which has ruby-3.0 by default, I could install Jekyll successfully using pacman but could not run it.

$ jekyll --help
/usr/lib/ruby/3.0.0/rubygems.rb:281:in `find_spec_for_exe': can't find gem jekyll (>= 0.a) with executable jekyll (Gem::GemNotFoundException)
	from /usr/lib/ruby/3.0.0/rubygems.rb:300:in `activate_bin_path'
	from /usr/bin/jekyll:23:in `<main>'

I don’t like to fight with installation process. And also I know very little about ruby. So I turned to docker which I have used in the past.

TLDR: Here is my Makefile. I execute the command make in the Github repository of this site to build and test this site.

JEKYLL_VERSION := 3.8

JEKYLL := docker run --rm \
	--volume="$(PWD):/srv/jekyll" \
	--volume="$(PWD)/vendor/bundle:/usr/local/bundle" \
	-p 4000:4000 \
	-it jekyll/jekyll:$(JEKYLL_VERSION) jekyll

all :
	$(JEKYLL) serve

If you are familiar with makefiles, you would notice the core command. You can directly run this command in bash. Note the small tweak since bash and make has different syntax for expanding variable: $(FOO) in Makefile is equivalent to $FOO or ${FOO} in bash.

$ docker run --rm \
	--volume="$PWD:/srv/jekyll" \
	--volume="$PWD/vendor/bundle:/usr/local/bundle" \
	-p 4000:4000 \
	-it jekyll/jekyll:3.8 jekyll serve

Option -p 4000:4000 binds port 4000 of docker container to localhost:4000. Without this option, http://localhost:4000 in your browser will not show any content. Option --volume="$(PWD)/vendor/bundle:/usr/local/bundle" to make sure that gems installed during the run process are not lost.