Liveness monitor for ruby programs

checker.rb

# Have your health checker execute this
require './liveness_monitor'

puts LivenessMonitor.new.status

liveness_monitor.rb

require 'socket'

class LivenessMonitor
  attr_accessor :port

  def initialize(port = 5678)
    @port = port
  end

  def start(callback)
    Thread.new do
      server = TCPServer.new 5678

      while session = server.accept
        session.puts callback.call
        session.close
      end
    end
  end

  def status
    server = TCPSocket.new 'localhost', 5678
    out = ''

    while line = server.gets
      out += line
    end
    server.close
    out
  end
end

server.rb

require './liveness_monitor'

# Probably you put this in an initializer, where the checker
# is actually inspecting some kind of heatbeat, or at the very least
# an indication that the program has fully started

# Maybe return '' for healthy, and an error message otherwise?
checker = ->{ "Hello world! The time is #{Time.now}" }
LivenessMonitor.new.start(checker)

# This stuff just keeps the program running, pretend its your real workload
puts 'server started'

while input = gets
  puts "Did you just say '#{input.strip}'?"
end