Kubelet

kubelet process in Kubernetes is responsible for running containers on the node

• Configuration: /etc/kubernetes/kubelet.conf
• Logs:
  • /var/log/kubelet.log
  • GKE: gcloud logging read projects/your-project/logs/kubelet
• Port: kubelet listen on port 10250

• Installation Ubuntu: snap install kubelet --classic (snap stop kubelet.daemon or snap start kubelet.daemon)

Commands

systemctl start snap.kubelet.daemon.service
systemctl stop snap.kubelet.daemon.service

snap start kubelet.daemon
Started.
systemctl status snap.kubelet.daemon.service

Networking

The Container Network Interface (CNI) plugin is selected by passing kubelet the --network-plugin=cni

Logs

[kubelet-check] The HTTP call equal to 'curl -sSL http://localhost:10248/healthz' failed with error: Get http://localhost:10248/healthz: dial tcp 127.0.0.1:10248: connect: connection refused.

E1122 21:44:49.860990    2153 remote_runtime.go:334] "ContainerStatus from runtime service failed" err="rpc error: code = DeadlineExceeded desc = context deadline exceeded" containerID="54f47d9bd75961b31d996d3e1d01d366467750e8b2d9b21af2f528ed2eead846"

• NodeHasDiskPressure
• EvictionThresholdMet
• NodeHasInsufficientMemory
• rebooted

Related terms

• Liveness probe: (livenessProbe)
• Readiness probe: (readinessProbe)
• systemctl stop snap.kubelet.daemon.service
• kubectl describe pods | grep Unhealthy
• Kubelet Container Runtime Interface (CRI)
• systemctl status kubelet
• gcloud logging read projects/yourproject/logs/kubelet
• Kubernetes controller manager
• Conditions: kubelet is posting ready status. AppArmor enabled
• --kubelet-insecure-tls
• MemoryPressure
• kubectl get events Starting kubelet

cloud-node-lifecycle-controller

• Node-pressure Eviction
• kind: KubeletConfiguration
• oom_score_adj

Activities

• CKA v1.15: Understand LivenessProbes and ReadinessProbes

News

• 05/2022 Kubernetes 1.24: dockershim removed from kubelet

See also

• kubelet, Pod Lifecycle Event Generator (PLEG), Kubelet conditions, /etc/kubernetes/kubelet.conf, /var/log/kubelet.log, Kubelet Container Runtime Interface (CRI), crictl, context deadline exceeded, E1122, E1124, Starting kubelet, NodeHasDiskPressure, NodeHasInsufficientMemory, rebooted, Node-pressure Eviction, Kubelet logs, manager: kubelet
• Kubernetes Components, kube-proxy, kube-scheduler, kube-apiserver, kubelet, kubectl, kubeadm, Kubernetes controller manager, Kubernetes controllers, Kubernetes Addons, Kubernetes Topology Manager