parallel.rb

#!/usr/bin/env ruby

# Run several commands for different directories at the same time and multiplex their output with color-coded app labels.
#
# Usage:
#
#     ruby parallel.rb "foo:$HOME/projects/foo:bundle exec rake db:migrate" "bar:$HOME/projects/bar:bundle exec rake db:migrate"
#
# The output will look something like this (but the prefix labels will have different colors):
#
#     foo     == 20170310111111 Foo: migrating ==============================================
#     foo     bla bla bla
#     foo     == 20170310111111 Foo: migrated (0.0000s) =====================================
#     bar     == 20170320222222 Bar: migrating ==============================================
#     bar     yada yada yada
#     bar     == 20170320222222 Bar: migrated (0.0000s) =====================================

require 'open3'

COLORS = {
  red:            '0;31',
  green:          '0;32',
  yellow:         '0;33',
  blue:           '0;34',
  magenta:        '0;35',
  cyan:           '0;36',
  bright_red:     '1;31',
  bright_green:   '1;32',
  bright_yellow:  '1;33',
  bright_blue:    '1;34',
  bright_magenta: '1;35',
  bright_cyan:    '1;36'
}

threads = []

use_rvm = ARGV.delete('--rvm')

ARGV.each_with_index do |command, index|
  (app, path, command) = command.split(':', 3)
  color = COLORS.values[index % COLORS.values.size]
  cmd = [
    "cd #{path}",
    use_rvm ? "rvm use $(cat .ruby-version)" : nil,
    command
  ].compact.join(' && ')
  cmd = "bash -lc #{cmd.inspect}".gsub(/\$/, "\\$")
  threads << Thread.new do
    (_, out, wait_thr) = Open3.popen2e(cmd)
    puts "\e[#{color}m#{app.ljust(18)[0...18]}\e[0m#{out.gets}" until out.eof?
    out.close
    code = wait_thr.value.exitstatus
    exit code unless code.zero?
  end
end

threads.each(&:join)