Pods

One or more tightly coupled containers

A Pod wraps one or more containers that share a network address, can share volumes, and are always scheduled together on the same node. Most pods run one main container, sometimes with sidecars (log shippers, proxies) or init containers that run first. Pods are ephemeral: when one dies or its node fails it is not resurrected; a controller creates a new pod with a new IP. You rarely create pods directly; use a Deployment, StatefulSet, DaemonSet or Job to manage them.

Pods, Deployments, rollouts and jobs

Controllers manage pods for long-running services and run-to-completion tasks.

A pod with an init container and a sidecar

Not applied to a live cluster in this course; check field names against the API reference for your version.

apiVersion: v1
kind: Pod
metadata:
  name: web-debug
  labels: {app: web}
spec:
  initContainers:
  - name: wait-for-db
    image: busybox:1.36
    command: ["sh", "-c", "until nc -z db 5432; do sleep 2; done"]
  containers:
  - name: web
    image: ghcr.io/example/web:1.4.0
    ports: [{containerPort: 8080}]
  - name: log-shipper
    image: fluent/fluent-bit:3.0

Never rely on pod IPs

Pods come and go with new addresses; reach them through Services.

त्वरित जाँच: What happens to a pod when its node dies?

• It moves with the same IP
• It is gone; a controller creates a replacement pod with a new IP
• It is paused until the node returns
• The cluster stops