main.rb

# frozen_string_literal: true

require 'thor'
require 'git'
require 'fileutils'

# WIP WIP WIP
class Main
  class << self
    NAME = 'ruby'
    URI = "https://github.com/docker-library/#{NAME}.git"
    DIRECTORY = './tmp/'

    def clone_source
      Git.clone(URI, NAME, path: './tmp/', depth: 1)
    end

    def call
      begin
        FileUtils.remove_dir('./tmp')
      rescue StandardError
        Errno::ENOENT
      end
      clone_source
      Dir.chdir(File.join(DIRECTORY, NAME)) do
        Replace.new.in_project
      end

      Replace.new.root
    end
  end
end

# WIP WIP WIP
class Replace < Thor
  include Thor::Actions

  def in_project
    puts `cp '.travis.yml' '../../'`

    insert_into_file 'Dockerfile-slim.template',
                     "\t\tlibjemalloc-dev \\\n",
                     after: "libgdbm3 \\\n"

    insert_into_file 'Dockerfile-slim.template',
                     "\t\t--with-jemalloc \\\n",
                     after: "--enable-shared \\\n"

    append_file 'Dockerfile-slim.template', <<~RUBY
       # Sanity check for jemalloc
      RUN ruby -r rbconfig -e "abort 'jemalloc not enabled' unless RbConfig::CONFIG['LIBS'].include?('jemalloc')"
    RUBY

    puts `PATH="/usr/local/opt/coreutils/libexec/gnubin:$PATH" ./update.sh`
  end

  def root
    insert_into_file '.travis.yml',
                     <<~YAML,
                         - bundle install
                         - bundle exec ruby main.rb
                         - cd ./tmp/ruby/
                       #
                     YAML
                     after: "before_script:\n"

    # Only build slim builds for now
    comment_lines '.travis.yml', /VARIANT=/
    uncomment_lines '.travis.yml', /VARIANT=.*\/slim$/

    # Skip Ruby 2.6-rc until jemalloc fix is released
    comment_lines '.travis.yml', /VERSION=2\.6-rc/
  end
end

Main.call

# Test: cd tmp/ruby/; export VERSION=2.5 VARIANT=stretch/slim; cd "$VERSION/$VARIANT"; export slash='/'; image="jemalloc/ruby:${VERSION}-${VARIANT//$slash/-}"; docker build -t "$image" .