Kubernetes Pods

A Pod is the smallest deployable unit in Kubernetes. It wraps one or more containers that share a network namespace and storage volumes.

Pod vs Container

A Pod is not a container — it is a wrapper around one or more containers. Containers in the same pod:

Share the same IP address and port space
Can communicate via localhost
Share mounted volumes

Most pods run a single container. Multi-container pods are used for sidecar patterns (e.g., a log shipper alongside the main app).

Minimal Pod Spec

apiVersion: v1
kind: Pod
metadata:
  name: my-app
  labels:
    app: my-app
spec:
  containers:
    - name: my-app
      image: nginx:1.25
      ports:
        - containerPort: 80

Apply it:

kubectl apply -f pod.yaml

Pod Lifecycle Phases

Phase	Meaning
`Pending`	Accepted but not yet scheduled or image not yet pulled
`Running`	At least one container is running
`Succeeded`	All containers exited with code 0
`Failed`	At least one container exited with non-zero code
`Unknown`	Node communication lost

Resource Requests and Limits

Always set these to help the scheduler and protect other workloads:

resources:
  requests:
    memory: "64Mi"
    cpu: "250m"
  limits:
    memory: "128Mi"
    cpu: "500m"

requests — minimum guaranteed resources
limits — maximum allowed before throttling (CPU) or OOM kill (memory)

Common kubectl Commands for Pods

# List pods in current namespace
kubectl get pods

# Detailed pod info (events, conditions, IP)
kubectl describe pod my-app

# View logs
kubectl logs my-app
kubectl logs my-app --previous       # logs from last crashed container

# Open a shell inside the container
kubectl exec -it my-app -- /bin/sh

# Delete a pod
kubectl delete pod my-app

# Watch pod status changes live
kubectl get pods -w

Liveness and Readiness Probes

livenessProbe:
  httpGet:
    path: /health
    port: 8080
  initialDelaySeconds: 10
  periodSeconds: 5

readinessProbe:
  httpGet:
    path: /ready
    port: 8080
  initialDelaySeconds: 5
  periodSeconds: 3

liveness — restart the container if this fails
readiness — remove the pod from service endpoints until this passes

Why Pods Are Ephemeral

Never rely on a pod’s IP address or local file system. Pods can be rescheduled to different nodes at any time. Use:

Services for stable network access
PersistentVolumes for durable storage
Deployments to manage pod lifecycle (not raw pods)

In practice, you almost never create bare pods — you create Deployments, which manage pods for you.