Dalton Hubble f1f4cd6fc0 Inline Container Linux kubelet.service, deprecate kubelet-wrapper ... * Change kubelet.service on Container Linux nodes to ExecStart Kubelet inline to replace the use of the host OS kubelet-wrapper script * Express rkt run flags and volume mounts in a clear, uniform way to make the Kubelet service easier to audit, manage, and understand * Eliminate reliance on a Container Linux kubelet-wrapper script * Typhoon for Fedora CoreOS developed a kubelet.service that similarly uses an inline ExecStart (except with podman instead of rkt) and a more minimal set of volume mounts. Adopt the volume improvements: * Change Kubelet /etc/kubernetes volume to read-only * Change Kubelet /etc/resolv.conf volume to read-only * Remove unneeded /var/lib/cni volume mount Background: * kubelet-wrapper was added in CoreOS around the time of Kubernetes v1.0 to simplify running a CoreOS-built hyperkube ACI image via rkt-fly. The script defaults are no longer ideal (e.g. rkt's notion of trust dates back to quay.io ACI image serving and signing, which informed the OCI standard images we use today, though they still lack rkt's signing ideas). * Shipping kubelet-wrapper was regretted at CoreOS, but remains in the distro for compatibility. The script is not updated to track hyperkube changes, but it is stable and kubelet.env overrides bridge most gaps * Typhoon Container Linux nodes have used kubelet-wrapper to rkt/rkt-fly run the Kubelet via the official k8s.gcr.io hyperkube image using overrides (new image registry, new image format, restart handling, new mounts, new entrypoint in v1.17). * Observation: Most of what it takes to run a Kubelet container is defined in Typhoon, not in kubelet-wrapper. The wrapper's value is now undermined by having to workaround its dated defaults. Typhoon may be better served defining Kubelet.service explicitly * Typhoon for Fedora CoreOS developed a kubelet.service without the use of a host OS kubelet-wrapper which is both clearer and eliminated some volume mounts		2019-12-29 11:17:26 -08:00
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kubernetes	Inline Container Linux kubelet.service, deprecate kubelet-wrapper	2019-12-29 11:17:26 -08:00