Overview of Kubernetes Components and Plugins

Kubernetes (K8s) Components K8s clusters consist of core components, including Master and Worker nodes, which manage and run applications. The Master runs the API server, scheduler, etc., while Workers run kubelet and the container runtime.

Plugins extend K8s functionality. Examples include Network Plugins (e.g., Calico, Flannel), Volume Plugins (e.g., GlusterFS, NFS), and Ingress Plugins (e.g., Traefik, HAProxy) that provide networking, storage, and external traffic support.

Kubernetes DNS is a core component that resolves DNS queries for services and endpoints, enabling applications to access external resources via stable DNS names. It updates records automatically when services change.

Example commands for DNS:

kubectl run dns-example --image=dnsutils --restart=Never

kubectl exec -ti dns-example nslookup myservice.mydomain.com

cat <

dig myservice.mydomain.com

Kubernetes Dashboard provides a graphical UI to view and manage cluster objects (nodes, pods, services, deployments) and supports monitoring, alerts, and auto‑completion.

kubectl proxy

kubectl get pods --namespace default

kubectl edit pods mypod --namespace=default

kubectl logs mypod --namespace=default

Heapster is a monitoring plugin that collects CPU, memory, and network metrics, sending them to tools like InfluxDB or Grafana.

helm install stable/heapster --name heapster

kubectl top pods

kubectl top pods --all-namespaces

heapster rules create rule.yml

Ingress Controller forwards external traffic into the cluster using Ingress resources, supporting load balancing and SSL termination.

helm install stable/nginx-ingress

cat <

curl https://example.com/

Kubelet runs on each node as a daemon, receiving tasks from the API server, creating and destroying pods, and monitoring pod status.

cat <

kubectl set image my-pod=my-image

kubectl delete pod my-pod

Container Runtime (Docker or compatible runtimes) provides the low‑level virtualization layer for K8s, handling image management, container execution, networking, and storage.

docker ps

docker pull <image>

docker images

docker run <image>

Network Plugin manages network connectivity on nodes. Types include Overlay (Flannel, Calico), Underlay, and CNI plugins.

helm install stable/flannel-crd --name flannel-crd

helm install stable/flannel --set network-plugin=flannel-crd --version=v0.9.1

kubectl get pods --output=jsonpath='{range .items[*]}{.status.podIP}{end}'

ip route show table local

dig @<pod-ip> <host>

Volume Plugin provides persistent storage for pods, supporting NFS, GlusterFS, AWS EBS, etc.

cat <

cat <

kubectl cp source-pod:/path/to/data destination-pod:/path/to/data

Ingress Plugin (e.g., NGINX, Traefik) enables external access, SSL, load balancing, and URL rewriting.

helm install stable/nginx-ingress

cat <

kubectl patch secret example-secret -p '{"data":{"tls.crt":"$(cat cert.pem | base64 | tr -d '\n')","tls.key":"$(cat key.pem | base64 | tr -d '\n')"}}'

curl https://example.com/

Other Plugins such as Job, CronJob, Scheduler, and Autoscaler extend Kubernetes functionality for batch processing, scheduled tasks, pod placement, and automatic scaling.

cat <

cat <

helm install stable/scheduler --name scheduler-example

kubectl autoscale deployment example-deployment --min=1 --max=5