POC getting cpu% from cgroups

poc.py

#!/usr/bin/env python
# Usage:
#    curl -sL https://gist.githubusercontent.com/joemiller/d89002a0d169cbb977e735df20e4ebd7/raw/poc.py | python | sort -rnk3 | head -n10
# or with a different INTERVAL:
#    curl -sL https://gist.githubusercontent.com/joemiller/d89002a0d169cbb977e735df20e4ebd7/raw/poc.py | INTERVAL=60 python | sort -rnk3 | head -n10

import os
import time

def main():
    stats = {}
    interval = 10
    if os.getenv('INTERVAL'):
        interval = float(os.getenv('INTERVAL'))

    for cgroup in os.listdir('/sys/fs/cgroup/cpuacct/containers.slice'):
        if cgroup.startswith('containers-'):
            with open(os.path.join('/sys/fs/cgroup/cpuacct/containers.slice', cgroup, 'cpuacct.usage')) as f:
                val = f.read().strip()
                stats[cgroup] = {}
                stats[cgroup]['start'] = int(val)
                # get wallclock time in nanoseconds. in python3.7+ we can use time.time_ns() instead here
                stats[cgroup]['start_time'] = time.time()*(10**9)

    time.sleep(interval)
    end_time = time.time()*(10**9)

    for cgroup in os.listdir('/sys/fs/cgroup/cpuacct/containers.slice'):
        if cgroup.startswith('containers-'):
            with open(os.path.join('/sys/fs/cgroup/cpuacct/containers.slice', cgroup, 'cpuacct.usage')) as f:
                val = f.read().strip()
                if cgroup in stats:
                    stats[cgroup]['end'] = int(val)
                    stats[cgroup]['end_time'] = time.time()*(10**9)

    for cgroup in stats:
        cpu_ns = (stats[cgroup]['end'] - stats[cgroup]['start'])
        runtime_ns = (stats[cgroup]['end_time'] - stats[cgroup]['start_time'])
        percentage = (float(cpu_ns)/runtime_ns)
        print cgroup, cpu_ns, (percentage * 100)

if __name__ == '__main__':
    main()