/sys/fs/cgroup

version: '3'
services:
  redis:
    image: redis
  datadog:
    build: datadog
    pid: host
    environment:
     - DD_API_KEY=${DD_API_KEY}
     - DD_SITE=datadoghq.com
    volumes:
     - /var/run/docker.sock:/var/run/docker.sock
     - /proc/:/host/proc/:ro
     - /sys/fs/cgroup:/host/sys/fs/cgroup:ro

/sys/, /sys/bus/usb/, /sys/fs/, /sys/class/net/, /sys/kernel/