pbot/applets/pbot-vm/host/bin/vm-watchdog

#!/usr/bin/env perl

# File: vm-watchdog
#
# Purpose: Monitors pbot-vm cpu usage. Resets vm to snapshot if cpu exceeds
# threshold limits.

# SPDX-FileCopyrightText: 2021 Pragmatic Software <pragma78@gmail.com>
# SPDX-License-Identifier: MIT

use warnings;
use strict;

use Proc::ProcessTable;
use IO::Socket;

my $SLEEP      = 15;
my $MAX_PCTCPU = 25;
my $QEMU       = 'qemu-system-x86';
my $DOMAIN     = 'pbot-vm';

my $last_pctcpu = 0;

sub reset_vm {
  print "Resetting vm\n";
  system("virsh snapshot-revert $DOMAIN 1");
  print "Reset vm\n";
}

while (1) {
  my $t = Proc::ProcessTable->new(enable_ttys => 0);

  foreach my $p (@{$t->table}) {
    if ($p->fname eq $QEMU and $p->cmndline =~ m/guest=\Q$DOMAIN\E/) {
      # $p->pctcpu never updates? so we use top instead.
      my $pctcpu = `top -b -n 1 -p $p->{pid} | tail -n 1 | awk '{print \$9}'`;
      $pctcpu =~ s/^\s+|\s+$//g;
      print scalar localtime, " :: Got $DOMAIN qemu pid: $p; using $pctcpu cpu\n" if $pctcpu > 0;

      if ($pctcpu >= $last_pctcpu and $last_pctcpu >= $MAX_PCTCPU) {
        reset_vm;
        $last_pctcpu = 0;
      } else {
        $last_pctcpu = $pctcpu;
      }
    }
  }
  sleep $SLEEP;
}