app.ru

require 'rack'
require 'rack/server'

class HelloWorld
  def response
    [200, {}, ['Hello World']]
  end
end

class HelloWorldApp
  def self.call(env)
    HelloWorld.new.response
  end
end

run HelloWorldApp

Gemfile

source "https://rubygems.org"

gem 'puma'
gem 'rack'

script.sh

function cyclepuma {
  sleep 5
  cluster_pid=$1
  echo "cluster pid: $cluster_pid"

  while $(kill -s 0 $cluster_pid); do
    curl "http://localhost:9292"
    sleep 5
    echo "decrement"
    kill -s TTOU $cluster_pid # decrement
    sleep 5
    echo "increment"
    kill -s TTIN $cluster_pid # increment
  done

  echo "puma is dead"
}

echo "== starting puma in background"
puma app.ru -t 1:1 -w 5 --preload --debug &
pumapid=$!
echo "preparing to kill puma"
cyclepuma $pumapid

kill -9 $pumapid