snapd

  1. Bug #1664638
  2. Comment #0

Comment 0 for bug 1664638

Revision history for this message
George Kraft (cynerva) wrote : Need an interface to access cgroups

Working on creating a confined snap for kubelet. We're seeing a lot of errors trying to open files relating to cgroups:

/proc/self/cgroup
/sys/fs/cgroup/cpu,cpuacct/cpu.shares
/sys/fs/cgroup/cpu,cpuacct/cpu.cfs_period_us
/sys/fs/cgroup/cpu,cpuacct/cpu.cfs_quota_us
/sys/fs/cgroup/memory/memory.limit_in_bytes
/sys/fs/cgroup/memory/memory.soft_limit_in_bytes
/sys/fs/cgroup/blkio
/sys/fs/cgroup/memory
/sys/fs/cgroup/cpuset

The last three result in a hard failure of kubelet. There may be other files as well.

Based on snappy-debug output, it looks like it's opening these files with the "r" flag, but I imagine it may need write access to some of these as well. I'm not sure.

For some context, kubelet is the main process that runs on each node in a Kubernetes cluster. Its main purpose is to orchestrate Docker containers, and it looks like it's using cgroups for tight control over the utilization of hardware resources.