add NetUsage module for Linux, reading from /sys/class/net/$interface/statistics

lib/Core/Linux/NetUsage.pm

+package Core::Linux::NetUsage;
+
+use strict;
+use warnings;
+
+use base 'Resmon::Module';
+
+use POSIX qw(strftime);
+use Time::HiRes qw(gettimeofday usleep);
+
+use Resmon::ExtComm qw(run_command cache_command);
+
+=pod
+
+=head1 NAME
+
+Core::Linux::NetUsage - Linux network interface throughput stats
+
+=head1 SYNOPSIS
+
+ Core::Sample {
+     check_name : interface => arg1
+ }
+
+=head1 DESCRIPTION
+
+This module obtains network usage statistics on a Linux machine
+by reading the /proc filesystem (like netstat and ifconfig do). 
+
+=head1 CONFIGURATION
+
+=over
+
+=item check_name
+
+Description only, non-normative.
+
+=item interface
+
+The interface to obtain statistics for, like C<eth0>. Defaults to
+C<eth0> if not specified.
+
+=back
+
+=head1 METRICS
+
+=over
+
+=item rx_bytes
+
+Count, in bytes, of packets received on the interface.
+
+=item tx_bytes
+
+Count, in bytes, of packets sent on the interface.
+
+=back
+
+=cut
+
+sub new {
+    my ($class, $check_name, $config) = @_;
+    my $self = $class->SUPER::new($check_name, $config);
+
+    bless($self, $class);
+    return $self;
+}
+
+sub handler {
+    my $self = shift;
+    my $config = $self->{config};
+    my $interface = $config->{interface};
+    print "I have ${interface}\n";
+
+    my $stats = get_network_statistics_for($interface);
+    return $stats;
+};
+
+
+sub get_network_statistics_for {
+  my ($interface) = @_;
+
+  my $dir = "/sys/class/net/$interface/statistics";
+
+  my $stats = {};
+  my @stats = qw/rx_bytes tx_bytes/;
+  for my $stat (@stats) {
+    $stats->{$stat} = do {
+      open my $fh, '<', "${dir}/${stat}" or die "${dir}/${stat}: $!";
+      local $/;
+      <$fh>;
+    };
+    chomp $stats->{$stat};
+  }
+
+  return $stats;
+}
+
+1;