Kubernetes Management

A few main commands to interact with clusters:

• Create resources: kubectl create secret generic <name> --from-literal=key=valCopied!, kubectl create configmap <name> --from-literal=key=valCopied!
• Get resources: kubectl get podsCopied!, kubectl get servicesCopied!, kubectl get deploymentsCopied!
• Describe resources: kubectl describe pod <pod-name>Copied! (shows detailed events and state)
• Logs: kubectl logs <pod-name> -fCopied! (follow logs)
• Execute command: kubectl exec -it <pod-name> -- /bin/bashCopied!
• Apply manifest: kubectl apply -f <filename>.yamlCopied!
• Delete resource: kubectl delete -f <filename>.yamlCopied! or kubectl delete pod <pod-name>Copied!
• Context/Namespace: kubectl config get-contextsCopied!, kubectl config use-context <name>Copied!, kubectl get pods -n <namespace>Copied!

k9s: Terminal UI for Kubernetes

For a more productive experience, I highly recommend using k9s. It provides a terminal-based UI to manage your clusters, view logs, shell into pods, and more, without typing long kubectl commands.

Manifest Examples

Secret

Used to store sensitive data like passwords or tokens.

yamlCopy
apiVersion: v1
kind: Secret
metadata:
  name: my-secret
type: Opaque
data:
  username: YWRtaW4= # base64 for "admin"
  password: bXlwYXNzd29yZA== # base64 for "mypassword"

ConfigMap

Used for non-sensitive configuration data.

yamlCopy
apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  APP_COLOR: 'blue'
  API_URL: 'https://api.example.com'

Pod

The smallest deployable unit. Usually managed by Deployments.

yamlCopy
apiVersion: v1
kind: Pod
metadata:
  name: nginx-pod
  labels:
    app: nginx
spec:
  containers:
    - name: nginx
      image: nginx:latest
      ports:
        - containerPort: 80

Deployment

Manages a set of identical Pods, providing declarative updates and scaling.

yamlCopy
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - name: nginx
          image: nginx:1.21
          ports:
            - containerPort: 80

Service (ClusterIP)

Exposes the Pods on an internal IP within the cluster.

yamlCopy
apiVersion: v1
kind: Service
metadata:
  name: nginx-internal
spec:
  selector:
    app: nginx
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
  type: ClusterIP

Service (LoadBalancer)

Exposes the Service externally using a cloud provider's load balancer.

yamlCopy
apiVersion: v1
kind: Service
metadata:
  name: nginx-external
spec:
  selector:
    app: nginx
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
  type: LoadBalancer

Job

Creates one or more Pods and ensures that a specified number of them successfully terminate.

yamlCopy
apiVersion: batch/v1
kind: Job
metadata:
  name: hello-job
spec:
  template:
    spec:
      containers:
        - name: hello
          image: busybox
          command: ['echo', 'Hello Kubernetes Job!']
      restartPolicy: Never
  backoffLimit: 4

CronJob

Runs Jobs on a time-based schedule.

yamlCopy
apiVersion: batch/v1
kind: CronJob
metadata:
  name: hello-cronjob
spec:
  schedule: '*/1 * * * *'
  jobTemplate:
    spec:
      template:
        spec:
          containers:
            - name: hello
              image: busybox
              command: ['echo', 'Hello from CronJob!']
          restartPolicy: OnFailure