Kubernetes Rolling Update Strategy Guide

💡 Quick Answer: deployments

The Problem

This is one of the most searched Kubernetes topics with thousands of monthly searches. A comprehensive, production-ready guide prevents hours of trial and error.

The Solution

Rolling Update Configuration

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web-app
spec:
  replicas: 10
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 2              # Create 2 extra pods during update
      maxUnavailable: 1        # Remove at most 1 old pod at a time
  minReadySeconds: 10          # Wait 10s after Ready before continuing
  revisionHistoryLimit: 5      # Keep 5 old ReplicaSets for rollback

maxSurge vs maxUnavailable

Rollback

# Check rollout status
kubectl rollout status deployment/web-app

# View history
kubectl rollout history deployment/web-app
kubectl rollout history deployment/web-app --revision=3

# Rollback to previous
kubectl rollout undo deployment/web-app

# Rollback to specific revision
kubectl rollout undo deployment/web-app --to-revision=2

# Pause / Resume (canary-style)
kubectl rollout pause deployment/web-app
# Inspect new pods...
kubectl rollout resume deployment/web-app

Update Triggers

# Update image
kubectl set image deployment/web-app app=my-app:v2

# Update env var (triggers rollout)
kubectl set env deployment/web-app LOG_LEVEL=debug

# Restart without changes (force new pods)
kubectl rollout restart deployment/web-app

# Apply manifest changes
kubectl apply -f deployment.yaml

graph LR
    A[10 pods v1] -->|maxSurge=2| B[12 pods: 10 v1 + 2 v2]
    B -->|v2 Ready| C[11 pods: 9 v1 + 2 v2]
    C -->|Continue| D[...]
    D --> E[10 pods v2]
    F[Problem detected] -->|rollout undo| G[Back to v1]

Frequently Asked Questions

What triggers a rolling update?

Changes to .spec.template (container image, env vars, resources, labels). Changes to replicas, strategy, or metadata do NOT trigger a rollout.

maxSurge=0 and maxUnavailable=0?

Invalid — at least one must be >0. Otherwise the deployment can’t make progress (can’t add new pods AND can’t remove old pods).

Best Practices

• Start with the simplest configuration that solves your problem
• Test in staging before production
• Use kubectl describe and events for troubleshooting
• Document team conventions for consistency

Key Takeaways

• This is fundamental Kubernetes operational knowledge
• Follow established conventions and recommended labels
• Monitor and iterate based on real production behavior
• Automate repetitive tasks to reduce human error