Controller is a process that continuously monitor the state of various components within the system and work towards bringing the whole system to the desired functionin state

Node Controller check the status of the node via the kube-apiserver every five seconds (that way it can monitor the health of the node)

If node stop send heartbeat it wait 40 seconds before marking it unreachble

Eviction - it give the node 5m to comeback up, if it doesn’t, it removes the PODs assigned to that node and provisions them on the healthy ones if the PODs are part of a replica set

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Replication Controller - responsible of monitoring the status of replica set and ensuring that the desired number of PODs are available at all times within the set.

Other Controllers

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Kubernetes-Controller-Manager will pack them in a single package or process.

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