text: Running Metricbeat in a Container | Metricbeat Reference [5.1] | Elastic
  Metricbeat Reference [5.1] » Running Metricbeat in a Container
  If you have enabled cgroup reporting (an experimental feature) from the system process metricset, then you need to mount the host's cgroup mountpoints within the container. They need to be mounted inside the directory specified by the -system.hostfs CLI flag.