How to set up ruby on Docker - getting nokogiri error - ruby

Question

My Doc Dockerfile has FROM Ubuntu:18.04
I want to use ruby so i did
gem install bundler
However when I try to
bundle
I get an error with nokogiri
Installing nokogiri 1.10.2 with native extensions
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
current directory: /var/lib/gems/2.5.0/gems/nokogiri-1.10.2/ext/nokogiri
/usr/bin/ruby2.5 -r ./siteconf20190414-288-1mfprtc.rb extconf.rb
mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h
extconf failed, exit code 1
Gem files will remain installed in /var/lib/gems/2.5.0/gems/nokogiri-1.10.2 for inspection.
Results logged to /var/lib/gems/2.5.0/extensions/x86_64-linux/2.5.0/nokogiri-1.10.2/gem_make.out
An error occurred while installing nokogiri (1.10.2), and Bundler cannot continue.
Make sure that `gem install nokogiri -v '1.10.2' --source 'http://rubygems.org/'` succeeds before bundling.

Answer 1

You have a dependency called nokogiri that has external dependency, usually it's libxml and libxslt.
All you need to do is apt get install libxml2-dev libxslt1-dev
Here's a working example of a Ruby Dockerfile
FROM ruby:2.6.2
RUN apt-get update -qq && apt-get install -y build-essential
RUN apt-get install -y libxml2-dev libxslt1-dev
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app
COPY Gemfile* /usr/src/app/
RUN bundle install -j3
ADD . /usr/src/app
ENTRYPOINT ["bundle", "exec"]
CMD ["rails", "server"]