config.ru

# config.ru

run Proc.new { |env| ['200', {'Content-Type' => 'text/html'}, ['get rack\'d']] }

Gemfile

# frozen_string_literal: true

source "https://rubygems.org"

git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }

# gem "rails"

gem "puma", "~> 3.12"
gem "guard-puma", "~> 0.5.0"
gem "guard", "~> 2.15"

Gemfile.lock

GEM
  remote: https://rubygems.org/
  specs:
    coderay (1.1.2)
    ffi (1.9.25)
    formatador (0.2.5)
    guard (2.15.0)
      formatador (>= 0.2.4)
      listen (>= 2.7, < 4.0)
      lumberjack (>= 1.0.12, < 2.0)
      nenv (~> 0.1)
      notiffany (~> 0.0)
      pry (>= 0.9.12)
      shellany (~> 0.0)
      thor (>= 0.18.1)
    guard-compat (1.2.1)
    guard-puma (0.5.0)
      guard (~> 2.14)
      guard-compat (~> 1.2)
      puma (~> 3.6)
    listen (3.1.5)
      rb-fsevent (~> 0.9, >= 0.9.4)
      rb-inotify (~> 0.9, >= 0.9.7)
      ruby_dep (~> 1.2)
    lumberjack (1.0.13)
    method_source (0.9.2)
    nenv (0.3.0)
    notiffany (0.1.1)
      nenv (~> 0.1)
      shellany (~> 0.0)
    pry (0.12.2)
      coderay (~> 1.1.0)
      method_source (~> 0.9.0)
    puma (3.12.0)
    rb-fsevent (0.10.3)
    rb-inotify (0.9.10)
      ffi (>= 0.5.0, < 2)
    ruby_dep (1.5.0)
    shellany (0.0.1)
    thor (0.20.3)

PLATFORMS
  ruby

DEPENDENCIES
  guard (~> 2.15)
  guard-puma (~> 0.5.0)
  puma (~> 3.12)

BUNDLED WITH
   1.17.1

Guardfile

guard 'puma', :port => 4000 do
  watch('Gemfile.lock')
end