Pods

A Pod is the smallest unit you can deploy and manage in Kubernetes. It holds one or more containers, storage, a network identity, and instructions on how the containers should run.

• Basic Unit of Deployment: Kubernetes does not run containers directly. It always runs them inside Pods.
• Multiple Containers (Optional): A Pod can run one container or several that work closely together (like a main app and a helper).
• Shared Resources: Containers in the same Pod share the same storage and network. They can talk to each other using localhost.
• Ephemeral: Pods are temporary. If a Pod fails, Kubernetes creates a new one instead of fixing the old one.

• Containers: One or more app containers running inside the Pod.
• Storage Volumes: Shared storage that all containers in the Pod can use.
• Networking: A Pod gets its own IP. Containers inside the Pod use localhost to talk to each other.
• PodSpec: This defines what the Pod should run, how much CPU or memory it needs, and how to check its health.

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

• apiVersion: Version of the Kubernetes API
• kind: Type of object being created (Pod)
• metadata: Name and labels for the Pod
• spec: Defines what containers run and how
• containers: List of container definitions within the Pod

• kubectl run nginx --image=nginx – Create a Pod using imperative command
• kubectl get pods – List all Pods
• kubectl describe pod nginx-pod – View detailed Pod info
• kubectl delete pod nginx-pod – Delete a Pod
• kubectl apply -f pod.yaml – Create a Pod from YAML file

• Each Pod gets a unique IP address
• Containers inside a Pod use localhost to communicate
• Pods communicate with other Pods via the Kubernetes network

• Pending: Pod is created but not running yet
• Running: Containers are active
• Succeeded: Containers exited successfully
• Failed: One or more containers failed
• Unknown: Kubernetes can’t get Pod status

• Shared Resources: Share storage and networking
• Sidecar Containers: Use helper containers like loggers or proxies
• Kubernetes Integration: Pods are the unit Kubernetes schedules, scales, and monitors

• Single-Container Pods: Most Pods run a single container
• Multi-Container Pods: Use when tightly coupled containers must run together, like:
  • A web server with a logging sidecar
  • A database with a backup sidecar