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Continuous Integration for Ruby

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Originally published at mcartoixa.me on ・8 min read

I have had to deal with a few projects in Ruby recently and I have tried to adapt my practices to this new environment. On a personal level this means less cognitive load when I have to come back to these projects months later, even more so because Ruby is far from my area of expertise. As it happens I have had quite some trouble implementing Continuous Integration because of (seemingly) conflicting conventions. But I have tried anyway:

A simple project

My website (which includes my blog) is in fact based on Ruby, as it is a Jekyll project hosted on GitHub Pages (for now). Granted, it is not a proper Ruby project (as Ruby is not required on the target server for instance) but I find it is a good introduction to the concepts and the tools involved.

The main elements of the project are:

The build file

I don’t think there is much choice here in the build tool to use in a Ruby environment, so Rake it is. Here is the whole file:

PROJECT_NAME ||= 'www.mcartoixa.me'
PROJECT_VERSION ||= '0.0.0'

import 'build/common.rake'

Alright, I cheated. I like to gather everything build related in a build\ folder and I did that here. But what we loose in straightforwardness we gain in consistency, because in a Rails project, where many tasks and targets are imported, I find this actually brings more readability to the project.

So, what’s in there? The build file defines the following targets (ie tasks in Rake speak), overall consistent with what we have seen in other technologies:

  • build:clean: cleans the build (the tmp\ directory).
  • build:compile: creates the static version of the website (using Jekyll), ready for deployment (in the tmp\obj\bin\ folder).
  • build:test: tests the project.
    • I want to check the links in my website using HTMLProofer. I could use a Jekyll plugin for this, but testing links proves rather time consuming and error prone (more on that later) and I would rather keep it out of my development workflow.
  • build:analyze: checks deprecation and configuration issues (using Jekyll).
  • build:package: creates a deployable archive of the static version of the website (in the tmp\out\bin\​ folder).
    • This is of little use right now as everything is handled by GitHub pages, including deployment, but this is partly a proof of concept. And I like the freedom of knowing I could host my website elsewhere at any moment.
  • build:build: shortcut for the combination of build:compile, build:test and build:analyze.
  • build:rebuild: shortcut for the combination of build:clean and build:build.
  • build:release: shortcut for the combination of build:clean, build:build, and build:package.

What’s remarkable here is the use of namespaces in the tasks names. Again, this proves useful (and consistent) in a Rails project. And so the description of the build:compile task is simply:

namespace 'build' do
  task 'compile' do
    sh 'jekyll', 'build', '-dtmp/obj/bin/', 'JEKYLL_ENV=production', '--strict_front_matter'
  end
end

The build:test task is slightly more complicated, but is in fact mainly HTMLProofer configuration:

require 'html-proofer'
namespace 'build' do
  task 'test' => %w[compile]
  task 'test' do
    options = {
      :allow_hash_href => true,
      :assume_extension => true,
      :check_favicon => true,
      :check_opengraph => true,
      :file_ignore => [
        /\/blog\/software-craftsmanship\/20[01]\d\//, # Do not check old blog posts
        /\/sections\//
      ],
      :root_dir => 'tmp/obj/bin/',
      :url_ignore => [
        'http://html5up.net', 'https://chrisbobbe.github.io/', # Included by the template
        'https://www.facebook.com/mathieu.cartoixa', # 404 only when checked...
        'https://www.linkedin.com/in/cartoixa/', 'https://www.linkedin.com/in/cartoixa/?trk=profile-badge' # 999 only when checked
      ]
    }
    HTMLProofer.check_directory('tmp/obj/bin/', options).run
  end
end

And then the build:package task requires an external package for the creation of the archive: the default PackageTask does not seem to support well the archiving of files outside the root of the project. This gives something like:

require 'zip'
namespace 'build' do
  namespace 'package' do
    PACKAGE_FILE = 'tmp/out/bin/www.mcartoixa.me-0.0.0.zip'
    file PACKAGE_FILE => %w[build:compile]
    file PACKAGE_FILE do
      FileUtils.mkdir_p('tmp/out/bin/')
      Zip::File.open(PACKAGE_FILE, Zip::File::CREATE) do |zf|
        Rake::FileList.new('tmp/obj/bin/**/*').each do |f|
          zf.add(f.delete_prefix('tmp/obj/bin/'), f)
        end
      end
    end

    task 'build' => PACKAGE_FILE
  end
  task 'package' => %w[package:build]
end

Please note here that one of the main features of a build tool is the ability to describe dependencies between targets. This is demonstrated here:

  • the build:package task depends on build:​package:build.
  • the build:​package:build task depends on the rule to build tmp/out/bin/www.cartoixa.me-0.0.0.zip.
  • the rule to build tmp/out/bin/www.mcartoixa.me-0.0.0.zip depends on build:compile (the static website needs to have been created before attempting to package it).This might seem a bit confusing to the newcomer but it is in fact very powerful (when used sensibly).

The last thing I would like to add here is that HTMLProofer is a fine tool but:

  • I still have to find a way for it not to complain when I just added a new blog post that it in fact does not exist (yet).
  • sometimes websites will fail because… reasons, and it should not prevent my own build from succeeding. I guess I should make sure that it only triggers warnings instead of errors.

The script file

Having managed to run an instance of Redmine on Windows Server 2012 and IIS, I figured Ruby was a cross-platform technology. In reality I have since experienced that many dependencies that require native compilation are poorly (or not at all) maintained: running a Rails application with MariaDB and Redis connections is a nightmare (when possible at all).

Disclaimer aside (no build.bat then), the gist of the build.sh file is simply (using Bundler here):

if bundle check > /dev/null; then
  bundle clean
else
  bundle install --standalone --clean
fi

bundle exec rake build:${TASK}

The CI configuration file

We need a CI platform that runs MacOS or Linux, so Travis CI will do just fine. Once again, having dealt with all the difficulties in the build file, the .travis.yml is just:

before_install:
- gem install bundler
install:
- bundle install --standalone --clean --jobs=3 --retry=3
script:
- bundle exec rake build:release

A more complete project

This is where the trouble really begins. Having tried to apply the same principles to a more complex Rails project I came against difficulties that seem hard to overcome. This may be because of my lack of knowledge of the environment itself, but it might also be because of conflicting conventions. I have the sense for instance that everything is done to allow the developer to achieve everything (and anything) from the command line. This might mean many things like:

  • you don’t have to work in another directory, and in fact you should not. It seems quite a hassle (compared to Javascript for instance) to handle a copy of the source code elsewhere where you retrieve only production dependencies for packaging purposes.
  • some tools have memory. Bundler will remember your current environment (development, production) for instance.
  • worse, the so called Deployment Mode will explicitely screw up your development environment.

Hard to run your build locally with these features!… This is not intended as a rant though, and if you have some insight on how to reconcile both worlds: please share.

Though I cannot share a real and complete project here I can show Rakefile elements that can be of some use:

  • how to run Ruby to check your source files syntax (this goes in the build:compile target):
SOURCE_FILES = Rake::FileList.new('.ruby-*', 'config.ru', 'Gemfile*', 'Rakefile', 'app/ **/*', 'bin/** /*', 'config/ **/*', 'db/** /*', 'lib/ **/*', 'public/** /*', 'vendor/**/*') do |fl|
  fl.exclude(/^config\/app_parameters.yml$/)
  fl.exclude(/\.log$/)
end
RUBY_FILES = Rake::FileList.new(SOURCE_FILES.dup.to_a.select do |path|
  path.ends_with?('.rb')
end) do |fl|
  fl.exclude(/^vendor\//)
end

namespace 'build' do
  rule '.rb.log' => [
    proc { |tn| tn.gsub(/\.rb\.log$/, '.rb').sub(/tmp\/obj\//, '') }
  ] do |t|
    FileUtils.mkdir_p(File.dirname(t.name))
    ruby "-wc #{t.source} > #{t.name}"
  end
  task 'compile' => RUBY_FILES.gsub(/\.rb$/, '.rb.log').sub(/^/, 'tmp/obj/')
end

We define rules for *.rb.log files that will be generated by running Ruby on the corresponding *.rb file and storing the output. The task we define then depends on the generation of those files.

  • how to run Reek on your Ruby files (this creates a reek target):
require 'reek/rake/task'
Reek::Rake::Task.new do |t|
  t.config_file = '.reek.yml'
  t.source_files = RUBY_FILES
  t.reek_opts = '-s --force-exclusion --no-progress'
end
  • how to run Rubocop on your Ruby files (this creates a rubocop target):
require 'rubocop/rake_task'
RuboCop::RakeTask.new(:rubocop) do |t|
  t.formatters = ['clang', ['html', '-o', 'tmp/rubocop-results.html']]
  t.patterns = RUBY_FILES
end

As I wrote before, should you choose to use static analysis tools such as Reek and/or Rubocop (and you should), you should do it as soon as possible in the life of your project in order to avoid to have hundreds of warnings to correct at once…

Packaging proves the more challenging because when you are generating assets as part of the build (like minified Javascript files for instance), then you have to create file lists after those files have been generated (target assets:precompile in a Rails project). This gives something like:

require 'rake/packagetask'
PACKAGED_FILES = Rake::FileList.new(SOURCE_FILES.dup) do |fl|
  fl.exclude(/^app\/assets\//)
end
namespace 'build' do
  namespace 'package' do
    pt = Rake::PackageTask.new('my_application', '0.0.0') do |t|
      t.need_tar_gz = true
      t.package_dir = 'tmp/obj/bin/'
      t.package_files = PACKAGED_FILES
    end

    file pt.package_dir_path + '/public/assets' => %w[assets:precompile]
    file pt.package_dir_path + '/public/assets' do
      pt.package_files = pt.package_files + Rake::FileList.new('public/assets/**/*')
    end

    task 'build' => pt.package_dir_path + '/public/assets'
    task 'build' => %w[package]
    task 'build' do
      FileUtils.mkdir_p('tmp/out/bin/')
      FileUtils.mv(File.join(pt.package_dir, pt.tar_gz_file), 'tmp/out/bin/')
    end
  end
  task 'package' => %w[package:build]
end

The whole build kind of works when specifying specific command lines in the CI configuration (again this cannot be part of the local build):

bundle install --standalone=test --deployment
RAILS_ENV=test bundle exec rake build:release

Not ideal as we will be packaging with test dependencies as well (things like capybara or RSpec Rails). But hey: work in progress.

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