Datadog custom agent check to get the number of processes on a linux machine

custom_checkvalue.py

from checks import AgentCheck
from datadog_checks.base.utils.subprocess_output import get_subprocess_output

# Get number of processes from `vmstat`
class NumProcessesCheck(AgentCheck):
  def check(self, instance):
    out, err, retcode = get_subprocess_output(['vmstat', '1', '2'], self.log, raise_on_empty_output=True)
    lines = out.strip().split("\n")
    last_line = lines[-1]
    words = list(filter(None, last_line.split(" ")))
    first_word = words[0]
    num_threads = int(first_word)
    self.gauge('custom.num_scheduled_threads', num_threads)