Discussion on: How to create a Kubernetes cluster on Alpine Linux

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Firstly, thanks for writing this up.

I haven't much luck with getting kubelet up running on Alpine 3.12 (ppc64le)

$ /usr/bin/kubelet --bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf --config=/var/lib/kubelet/confi
g.yaml --resolv-conf=/run/systemd/resolve/resolv.conf

would fail with following output:

F0627 15:23:40.684395   24145 kubelet.go:1383] Failed to start ContainerManager failed to initialize top level QOS containers: failed to update top level Burstable QOS cgroup : failed to set supported cgroup subsystems for cgroup [kubepods burstable]: failed to find subsystem mount for required subsystem: pids

I would really appreciate if you could give me guidance on what the failure might be.

Many thanks in advance

P/S: I have no issue with setting up kubelet running under Ubuntu.

Trung Lê • Jun 28 '20 • Edited

I manage to resolve this issue by adding cgroup_enable=pids to the grub boot command:

# file: /etc/default/grub
- GRUB_CMDLINE_LINUX_DEFAULT="modules=sd-mod,usb-storage,ext4 nomodeset quiet rootfstype=ext4"
+ GRUB_CMDLINE_LINUX_DEFAULT="modules=sd-mod,usb-storage,ext4 nomodeset quiet rootfstype=ext4 cgroup_enable=pids"

This issue does not occur on x86_64 architecture and seems to me only impact ppc64le. I am investigating if it is related to the fact that CONFIG_CGROUP_PIDS is not enabled in the linux-lts kernel.

Trung Lê • Jun 29 '20 • Edited

FYI I've lodged a new Merge Request to enable CONFIG_CGROUPS_PIDS for linux-lts ppc64le (3.12-stable). This would address the issue at its root and users won't have to explicitly declare the cgroup_enable=pids in /etc/default/grub anymore.

$ cat /proc/cgroups 
#subsys_name    hierarchy   num_cgroups enabled
cpuset  2   1   1
cpu 3   1   1
cpuacct 4   1   1
memory  5   1   1
devices 6   1   1
freezer 7   1   1
net_cls 8   1   1
perf_event  9   1   1
pids    10  1   1 # <-- HERE IT IS :D