Blue-Green Deployments#

A blue-green deployment runs two identical production environments. One (blue) serves live traffic. The other (green) is idle or running the new version. When the green environment passes validation, you switch traffic from blue to green. If something goes wrong, you switch back. The old environment stays running until you are confident the new version is stable.

The fundamental advantage over rolling updates is atomicity. Traffic switches from 100% old to 100% new in a single operation. There is no period where some users see the old version and others see the new one.

Kubernetes Deployment Strategies#

Every deployment strategy answers the same question: how do you replace running pods with new ones without breaking things for users? The answer depends on your tolerance for downtime, risk appetite, and infrastructure complexity.

Rolling Update (Default)#

Rolling updates replace pods incrementally. Kubernetes creates new pods before killing old ones, keeping the service available throughout. This is the default strategy for Deployments.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web-api
spec:
  replicas: 4
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
      maxUnavailable: 1
  minReadySeconds: 10
  selector:
    matchLabels:
      app: web-api
  template:
    metadata:
      labels:
        app: web-api
    spec:
      containers:
      - name: web-api
        image: web-api:2.1.0
        readinessProbe:
          httpGet:
            path: /healthz
            port: 8080
          initialDelaySeconds: 5
          periodSeconds: 5

Key parameters:

Release Management Patterns#

Releasing software is more than merging to main and deploying. A disciplined release process ensures that every version is identifiable, every change is documented, every deployment is reversible, and failures are contained before they reach all users. This operational sequence walks through each phase of a production release workflow.

Phase 1 – Semantic Versioning#

Step 1: Adopt Semantic Versioning#

Semantic versioning (semver) communicates the impact of changes through the version number itself: MAJOR.MINOR.PATCH.