StatsD Monitoring

It's a bit hard to have the jailed process communicate with the parent.
This is a workaround and is really gross. Please forgive me.

monitor/.ruby-gemset

@@ -0,0 +1 @@
+tmate

monitor/.ruby-version

@@ -0,0 +1 @@
+ruby-1.9.3-p327

monitor/Gemfile

@@ -0,0 +1,3 @@
+source 'https://rubygems.org/'
+
+gem 'statsd-instrument'

monitor/Gemfile.lock

@@ -0,0 +1,10 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    statsd-instrument (1.5.0)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  statsd-instrument

monitor/monitor.rb

@@ -0,0 +1,35 @@
+#!/usr/bin/env ruby
+
+# It's a bit hard to have the jailed process communicate with the parent.
+# This is a workaround and is really gross. Please forgive me.
+
+require 'rubygems'
+require 'bundler'
+Bundler.require
+
+require 'logger'
+
+StatsD.server = 'monitor:8125'
+StatsD.logger = Logger.new(STDERR)
+StatsD.mode = 'production'
+
+loop do
+  server_count = 0
+  client_count = 0
+
+  Dir['/proc/*/cmdline'].map do |f|
+    if File.open(f).read =~ /^tmate-slave \[(.+)\] \((.+)\) (.+)$/
+      token = $1
+      role = $2
+      ip = $3
+
+      server_count += 1 if role == 'server'
+      client_count += 1 if role == 'client'
+    end
+  end
+
+  StatsD.gauge('tmate.server_count', server_count)
+  StatsD.gauge('tmate.client_count', client_count)
+
+  sleep 10
+end

tmate-slave.c

@@ -83,8 +83,8 @@ static void set_session_token(struct tmate_ssh_client *client,
 	memset(cmdline, 0, cmdline_end - cmdline);
 	sprintf(cmdline, "tmate-slave [%s] %s %s",
 		tmate_session_token,
-		client->ip_address,
-		client->role == TMATE_ROLE_SERVER ? "(server)" : "");
+		client->role == TMATE_ROLE_SERVER ? "(server)" : "(client)",
+		client->ip_address);
 }
 
 static char tmate_token_digits[] = "abcdefghijklmnopqrstuvwxyz"