Send a percentage of traffic to a new version with the Gateway API

Approach

Run the stable and canary versions as separate Deployments and Services, and split traffic with weighted backendRefs in an HTTPRoute. Change weights step by step while watching error rates.

Solution

apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata: {name: shop}
spec:
  parentRefs: [{name: public-gateway, namespace: infra}]
  hostnames: [shop.example.com]
  rules:
    - backendRefs:
        - {name: web-stable, port: 80, weight: 90}
        - {name: web-canary, port: 80, weight: 10}

Pitfalls

• Sticky sessions or caches that mix versions in one user journey unexpectedly.
• Database changes that the stable version can't handle.

Variations

• Header-based routing (matches: headers) to send internal users to the canary first.
• Argo Rollouts or Flagger to automate weights based on metrics.

Further reading: Gateway API: traffic splitting