How to monitor Unicorn and Puma unix socket queues with statsd

socket_stats_logger

#!/bin/bash

# Logs the queued and active stats from the application's sockets and posts to statsd

while true; do

  proc_lines=`cat /proc/net/unix`

  for file in /home/deploy/myapp/tmp/sockets/*.sock; do
    # /proc/net/unix lines are of the format:
    # Num       RefCount Protocol Flags    Type St Inode Path
    #
    # A queued connection (02) looks like:
    # 0000000000000000: 00000003 00000000 00000000 0001 02     0 /path/to/socket.sock
    #
    # An active connection (03) looks like:
    # 0000000000000000: 00000003 00000000 00000000 0001 03 132727691 /path/to/socket.sock
    queued=`echo "$proc_lines" | grep "02 \+[0-9]\+ \+$file" | wc -l`
    active=`echo "$proc_lines" | grep "03 \+[0-9]\+ \+$file" | wc -l`

    name=`basename $file .sock`

    echo -n "myapp.socket.$name.queued.g:$queued|g" > /dev/udp/localhost/8125
    echo -n "myapp.socket.$name.active.g:$active|g" > /dev/udp/localhost/8125
  done

  sleep 1
done

upstart.conf

description "Monitor the app's socket stats and send to statsd"
start on runlevel [2345]
stop on runlevel [!2345]

setuid app
setgid app

respawn

exec socket_stats_logger