Problem
When installing the new Kubernetes cluster collector (Checkmk 2.1), the following error appears (in the Kubernetes event logs)
Error: failed to start container "cadvisor": Error response from daemon: linux spec capabilities: Unknown capability to add: "CAP_CAP_SYS_PTRACE"
This happens when you are using older container runtime versions, which always add CAP_ to each capability drop.
This problem is fixed in Docker 19.03 and containerd 1.4.5
Solution
Change in the values.yaml under nodeCollector.cadvisor.securityContext:
capabilities: drop: - ALL add: ["SYS_PTRACE"]
(Remove the "CAP_")
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