I have some cgroups-managed services (actually running in docker). To fairly schedule some resource-demanding tasks, containerized services need to know it exact (as far as possible) resource usage. I've decided to read this metrics from cgroups.
But there is a problem. I known two ways to access cgroup data from docker container.
Mount cgroups directly from the inside of container. To accomplish that, I need to give CAP_SYS_ADMIN capability to container. I think this is too hard-boiled way to only read resource usage metrics.
Use docker volume, pointing to host cgroups mountpoint. This solution more or less appropriate, but I'am lookin' more elegant way.
I am not an "kernel-guy" and not familiar with kernel sources and documentation, so I am able to ask noob's question.
Is there any kernel interface which allows me to read cgroups metrics without mounting cgroups filesystem?
The only interface you get in the user space is by mounting cgroups or from the /proc/<pid>/cgourps, (but only limited to the cgroups a process belongs to). If you are looking for a syscall() for reading cgroups data, its not available IMU. Docker requires cgroups services (cgconfig, cgred, etc)to be running, therefore its would require you to mount the cgroups.