This component adds some useful controllers, operators and extensions to the `kube-system` namespace.
Quorum
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This is a simple set of pods, with a PodDisruptionBudget (PDB) of 1, which will be scheduled on control-plane hosts and prevents them from being drained e.g. during a update by accident. It's mainly there since one can not put PDBs on static pods. It's built to integrate nicely with the system-upgrades component.
Descheduler
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The descheduler is supposed to help rebalancing workload after updates and alike, since small clusters will otherwise run with quite unbalanced pods. The descheduler should rebalance workload, keeping each CPU a bit cooler and this way reduce potential noise as well as the risk for all workload when a single node fails.
Metrics-server
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The metrics-server is the standard component to provide basic pod metrics that can be used for vertial and horizontal pod autoscaling. Mainly here for completeness and insights using `kubectl top pods`.
Nice to knows
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-`kubeadm` doesn't provide proper certificates for the kubelet by default, which makes metrics-server require `--kubelet-insecure-tls` until one fixes the certificates.
- One has to explicitly enable `--authentication-token-webhook` for `kubeadm`-installed clusters in order to allow access to the metrics endpoint for metrics-server.
- One can't put PDBs on either daemonsets nor static-pods, therefore one requires a deployment to keep a quorum for e.g. etcd.
