What are the roles of Pod, Deployment, and Service in Kubernetes?

Pod

The smallest deployable unit in Kubernetes, containing one or more containers that share networking and storage.

• Containers in the same Pod share an IP address and localhost
• Pods are ephemeral — they don't auto-restart after crashing
• Avoid deploying Pods directly; use Deployments to manage them

Deployment

Manages the desired state of Pods, providing:

• Replica control: Maintains a specified number of Pod replicas
• Rolling updates: Gradually replaces old Pods to ensure zero-downtime updates
• Rollback: Quickly revert to a previous version

spec: replicas: 3 strategy: type: RollingUpdate rollingUpdate: maxUnavailable: 1 maxSurge: 1

Service

Provides a stable network endpoint so other services can discover and connect to Pods (since Pod IPs are dynamic).

Type	Description
ClusterIP	Accessible only within the cluster (default)
NodePort	Exposes via node IP + port
LoadBalancer	Integrates with cloud load balancers
ExternalName	Maps Service to an external DNS name

Relationship

Deployment → creates and manages Pods → Service uses Label Selectors to find Pods and route traffic