How to implement zero-downtime deployments in Kubernetes

Rolling Updates

Kubernetes Deployments support rolling updates by default. As new Pods become ready, old Pods are terminated gradually, ensuring continuous availability.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web
spec:
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 0
      maxSurge: 1

Health Probes

Liveness and readiness probes prevent traffic from reaching Pods that are not ready:

readinessProbe:
  httpGet:
    path: /healthz
    port: 8080
  initialDelaySeconds: 5
  periodSeconds: 10

Pre-Stop Hooks and Graceful Shutdown

Add a preStop hook or handle SIGTERM in your application to finish in-flight requests before exiting. This prevents abrupt disconnections during scale-down or updates.

For packaging the application, how to create a Kubernetes Helm chart from scratch standardizes manifests. For monitoring rollout health, how to set up Kubernetes monitoring with Prometheus provides essential metrics.