kube-controller-manager

• Manages various controllers in Kubernetes

• Controllers are responsible for verifying and responding when nodes, containers or endpoints go down. They make decisions to bring up new resources in such cases.

• The controllers are continuously watching the status of the pod (watch status)

• The controllers act to solve a failure situation (remediate situation)

Controllers

Node Controller

• Monitors the state of nodes
• Node Monitor Period = 5s: Check status of nodes every 5s
• Node Monitor Grace Period = 40s: Wait 40s before marking it unreachable
• Pod Eviction Timeout = 5m: Wait 5m before before considering a node dead and moving the pods to a healthy node

Replication Controller

• It's an older technology and has been replaced by replicaset
• Assure the desired number of containers are running
• The replication controller spans across multiple nodes in the cluster

Endpoints Controller

• Populates the endpoints objects (joins services & pods)

Service Account & Token Controller

• Creates default accounts and API Access for new namespaces

Cloud Controller

• Cloud-specific control logic
• On-Premise Kubernetes clusters won't have this component

Other controllers

• Controllers are enabled on the --controllers parameter

• By default enables all-by-default controllers

• List of all controllers

• attachdetach
• bootstrapsigner
• clusterrole-aggregation
• cronjob
• csrapproving
• csrcleaner
• csrsigning
• daemonset
• deployment
• disruption
• endpoint
• garbagecollector
• horizontalpodautoscaling
• job
• namespace
• nodeipam
• nodelifecycle
• persistentvolume-binder
• persistentvolume-expander
• podgc
• pv-protection
• pvc-protection
• replicateset
• replicationcontroller
• resourcequota
• root-ca-cert-publisher
• route
• service
• serviceaccount
• serviceaccount-token
• statefulset
• tokencleaner
• ttl
• ttl-after-finished