run_serf.rb

#!/usr/bin/env ruby

ip = `ip addr | grep eth0 | grep inet | awk '{print $2}' | cut -f1 -d"/"`

pid_file = "/var/run/serf.pid"

if File.exists? pid_file
  pid = File.read pid_file
  Process.kill "INT", pid rescue nil
end

pid = fork do
  File.open(pid_file, "w+") { |f| f.write Process.pid.to_s }
  exec "serf agent -role=app -bind=#{ip} -event-handler='user:deploy=/srv/app/deploy.rb'"
end

sleep 2

retries = 5

while retries > 0
  serf_join_err = `serf join #{ENV["SERF_HOST"]}`
  break if $?.exitstatus == 0
  retries -= 1
end

if retries == 0
  abort "Could not 'serf join' because #{serf_join_err}"
  exit $?.exitstatus
else
  Process.wait pid
end