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Cgroups and Services on Docker for AWS

(Dveenstra) #1

Hey guys,

Been poking around “Docker for AWS,” which launches a Docker Engine in Swarm mode on moby linux instances via AWS cloudformation. I’ve been investigating how this setup works and there’s a couple things that there seems to be no documentation for.

For one, on this distro, I can see that cgroup limits for CPU are being enforced but there appears to be no corresponding entry under /sys/fs/cgroup on the filesystem. Also, I cannot find the command for the system services manager. According to the documentation I could find, rc-status should work to show me the managed services on the instance, but it seems to not be installed as far as I can tell. There is also a directory called /sys/fs/cgroup/systemd/, but I’m not sure it’s actually doing anything.

Does anyone have any insight on how this is all working under the hood? Or can point me in the direction of some documentation that covers these details?

Would greatly appreciate any insight.

For reference, here is the version info for the OS and docker engine.

Kernel Version: 4.9.75-moby
Operating System: Alpine Linux v3.5
Server Version: 17.12.0-ce