public-access-proxy: collect haproxy stats

hosts/containers/public-access-proxy/default.nix

@@ -3,6 +3,7 @@
 {
   imports = [
     ./proxy.nix
+    ./stats.nix
   ];
 
   networking.hostName = "public-access-proxy";
@@ -40,5 +41,4 @@
   networking.firewall.allowedTCPPorts = [ 80 443 ];
 
   system.stateVersion = "18.09";
-
 }

hosts/containers/public-access-proxy/haproxy-stats.rb

@@ -0,0 +1,43 @@
+#!/usr/bin/env ruby
+
+require 'socket'
+
+HOSTNAME = IO::readlines("/proc/sys/kernel/hostname").join.chomp
+INTERVAL = 60
+
+def read_stats
+  sock = UNIXSocket.new("/run/haproxy/haproxy-stats.sock")
+  sock.send "show stat\n", 0
+  data = sock.read()
+  sock.close
+
+  cols = []
+  results = []
+  data.lines.each do |line|
+    line.chomp!
+    if line =~ /^#\s*(.+)$/
+      cols = $1.split(/,/)
+    else
+      rec = {}
+      cols.zip(line.split(/,/)).each do |col,val|
+        rec[col] = val if val and not val.empty?
+      end
+      results << rec
+    end
+  end
+  results
+end
+
+loop do
+  read_stats.each do |rec|
+    pxname = rec['pxname']
+    svname = rec['svname']
+    rec.each do |key,val|
+      next if key == 'pxname' or key == 'svname' or not val =~ /^\d+$/
+
+      puts "PUTVAL \"#{HOSTNAME}/haproxy_#{pxname}-#{svname}/current-#{key}\" interval=#{INTERVAL} N:#{val}"
+    end
+  end
+
+  sleep INTERVAL
+end

hosts/containers/public-access-proxy/stats.nix

@@ -0,0 +1,14 @@
+{ pkgs, lib, ... }:
+{
+  c3d2.hq.statistics.enable = true;
+
+  services.collectd.plugins.exec = ''
+    Exec "collectd" "${pkgs.ruby}/bin/ruby" "${./haproxy-stats.rb}"
+  '';
+
+  # add a socket that is world-accessible
+  services.haproxy.config = ''
+    global
+      stats socket /run/haproxy/haproxy-stats.sock mode 666
+  '';
+}