#!/usr/bin/perl -w
# -*- perl -*-

=head1 NAME

docker_cpu - Munin plugin to monitor docker container CPU usage.

=head1 APPLICABLE SYSTEMS

Should work on any Linux system that has docker support.

=head1 CONFIGURATION

Root privilege required to execute docker command.

1. Create a new file named "docker" inside the folder /etc/munin/plugin-conf.d/
2. Docker file content:

 [docker_cpu]
 user root

=head1 MAGIC MARKERS

 #%# family=auto
 #%# capabilities=autoconf

=head1 VERSION

 v.0.1

=head1 AUTHOR

Copyright (C) 2015 Samuel Cantero <scanterog at gmail dot com>

=head1 LICENSE

GPLv3

=cut

my $docker=`which docker`;

if ( defined $ARGV[0] and $ARGV[0] eq "autoconf" ) {
   if ($docker) {
      print "yes\n";
      exit 0;
   }
   else{
      print "no (Docker has not been found)\n";
      exit 0;
   }
}

$docker =~ s/\s+$//;

my @containers = split "\n" , `$docker ps --no-trunc=true`;
my $result;

for my $i (1 .. $#containers)
{
   my @fields = split / +/, $containers[$i];
   my $id = $fields[0];
   my $name = $fields[$#fields];
   my $label = $name;
   # manage container name containing arithmetic operators and dots. E.g, my-container.
   $name =~ s/[-\+*\/\.]/_/g;
   # truncate container name with "," character.
   $name =~ s/,.*//g;
   # prefix if container starts with 0-9
   $name =~ s/^([0-9])/c$1/;
   if (open(my $file, '<', "/sys/fs/cgroup/cpuacct/docker/$id/cpuacct.usage"))
   {
      my $total_cpu_ns = <$file>;
      $total_cpu_ns =~ s/\s+$//;
      close $file;
      if (open($file, '<', "/sys/fs/cgroup/cpuacct/docker/$id/cpuacct.usage_percpu"))
      {
         my @ncpu = split / /, <$file>;
         close $file;
         push @result, {'name'=>$name, 'label'=>$label, 'total_cpu_ns'=>$total_cpu_ns, 'ncpu'=>$#ncpu};
      }
   }
   elsif (open($file, '<', "/sys/fs/cgroup/system.slice/docker-$id.scope/cpu.stat"))
   {
      # handle cpu stats with cgroup v2
      # hexdump -C /sys/fs/cgroup/system.slice/docker-01fc4fa4d6cf7ad66efabc818dd1d99cc51fd8cebf6ba2345988b145029df09a.scope/cpu.stat
      # 00000000  75 73 61 67 65 5f 75 73  65 63 20 32 35 37 36 33  |usage_usec 25763|
      # 00000010  37 34 31 0a 75 73 65 72  5f 75 73 65 63 20 32 30  |741.user_usec 20|
      # 00000020  37 34 31 35 37 37 0a 73  79 73 74 65 6d 5f 75 73  |741577.system_us|
      # 00000030  65 63 20 35 30 32 32 31  36 33 0a 6e 72 5f 70 65  |ec 5022163.nr_pe|
      # 00000040  72 69 6f 64 73 20 30 0a  6e 72 5f 74 68 72 6f 74  |riods 0.nr_throt|
      # 00000050  74 6c 65 64 20 30 0a 74  68 72 6f 74 74 6c 65 64  |tled 0.throttled|
      # 00000060  5f 75 73 65 63 20 30 0a                           |_usec 0.|
      # 00000068
      my $total_cpu_ns = <$file>;
      $total_cpu_ns =~ s/^usage_usec ([0-9]+).*/$1/;
      $total_cpu_ns *= 1000;
      close $file;
      if (open($file, '<', "/sys/fs/cgroup/system.slice/docker-$id.scope/cpuset.cpus.effective"))
      {
         # hexdump -C /sys/fs/cgroup/system.slice/docker-5915a2718628754f9185a052b96c4ac4249692269ad03c54f9037cd9e530f93c.scope/cpuset.cpus.effective
         # 00000000  30 2d 31 31 0a                                    |0-11.|
         # 00000005
         #
         # docker run --cpuset-cpus 0,2,3,5,6,7,8 --rm bash sleep 60
         # 00000000  30 2c 32 2d 33 2c 35 2d  38 0a                    |0,2-3,5-8.|
         # 0000000a
         my $cpus = <$file>;
         $cpus =~ s/\s+$//;
         close $file;
         my $ncpu = 0;
         for $c (split /,/, $cpus)
         {
            @cpu_range = split /-/, $c;
            if ($#cpu_range == 0)
            {
               $ncpu += 1;
            }
            else
            {
               $ncpu += $cpu_range[1] - $cpu_range[0] + 1;
            }
         }
         push @result, {'name'=>$name, 'label'=>$label, 'total_cpu_ns'=>$total_cpu_ns, 'ncpu'=>$ncpu};
      }
   }
}

if (defined $ARGV[0] and $ARGV[0] eq "config")
{
   my $nanoSecondsInSecond=1000000000;
   my $graphlimit = 1;
   foreach(@result){
      if ($$_{'ncpu'} || 1 > $graphlimit){
         $graphlimit = $$_{'ncpu'};
      }
   }
   $graphlimit = $graphlimit * 100;
   print "graph_title Docker container CPU usage\n";
   print "graph_args --base 1000 -r --lower-limit 0 --upper-limit $graphlimit\n";
   print "graph_vlabel %\n";
   print "graph_scale no\n";
   print "graph_period second\n";
   print "graph_category virtualization\n";
   print "graph_info This graph shows docker container CPU usage.\n";

   foreach(@result)
   {
      print "$$_{'name'}.label $$_{'label'}\n";
      print "$$_{'name'}.draw LINE2\n";
      print "$$_{'name'}.min 0\n";
      print "$$_{'name'}.type DERIVE\n";
      print "$$_{'name'}.cdef $$_{'name'},$nanoSecondsInSecond,/\n";
   }
   exit 0;
}

# Note: Counters/derive need to report integer values.

foreach(@result)
{
   $tcpu = ($$_{'total_cpu_ns'}*100); #to percentage
   print "$$_{'name'}.value $tcpu\n";
}

# vim:syntax=perl