Common Deployment Strategies with Kubernetes

✡️ Recreate Deployment
Replaces the old version with the new one by terminating all old pods before starting new ones.

When to Use:
➤ Use when zero downtime isn’t critical and a clean slate of application state is required. Not so common.

Kubernetes Implementation:
➤ Set strategy.type to Recreate in the deployment manifest.

✡️ Rolling Deployment
Gradually replaces old instances with new ones without downtime.

When to Use:
➤ Use when high availability is essential and gradual rollouts are needed to prevent downtime. This is the most common strategy.

Kubernetes Implementation:
➤ Default strategy in Kubernetes.
➤ Controlled by maxSurge and maxUnavailable parameters in the deployment spec.

✡️ Blue-Green Deployment
Involves two environments (Blue for current, Green for new). Traffic switches to Green after testing, with easy rollback to Blue.

When to Use:
➤ When quick, risk-free rollback is needed if the new release fails.
➤ For critical applications requiring stability and controlled validation before going live.

Kubernetes Implementation:
➤ Maintain separate deployments for Blue and Green environments.
➤ Use Kubernetes services to route traffic between the two environments.

✡️ Canary Deployment
Gradually rolls out the new version by directing a small percentage of traffic to the canary while the rest goes to the stable version.

When to Use:
➤ Test new features with real traffic before a full rollout.
➤ Ideal for feature flags and gradual rollouts to minimize user impact and catch issues early.

Kubernetes Implementation:
➤ Use multiple replica sets with a smaller number of canary pods.
➤ Leverage Ingress, service meshes (Istio/Linkerd), or Argo CD for gradual rollouts.