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.

Building a Kubernetes Deployment Pipeline: From Code Push to Production#

A deployment pipeline connects a code commit to a running container in your cluster. This operational sequence walks through building one end-to-end, with decision points at each phase and verification steps to confirm the pipeline works before moving on.

Phase 1 – Source Control and CI#

Step 1: Repository Structure#

Every deployable service needs three things alongside its application code: a Dockerfile, deployment manifests, and a CI pipeline definition.

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:

Canary Deployments Deep Dive#

A canary deployment sends a small percentage of traffic to a new version of your application while the majority continues hitting the stable version. You monitor the canary for errors, latency regressions, and business metric anomalies. If the canary is healthy, you gradually increase its traffic share until it handles 100%. If something is wrong, you roll back with minimal user impact.

Why Canary Over Rolling Update#

A standard Kubernetes rolling update replaces pods one by one until all pods run the new version. The problem is timing. By the time you notice a bug in your monitoring dashboards, the rolling update may have already replaced most or all pods. Every user is now hitting the broken version.