Progressive Delivery: Beyond Rolling Updates
- Risk Mitigation: Progressive Delivery techniques (Canary, Blue-Green) reduce the impact of faulty deployments by gradually exposing new versions to users.
- Automated Rollbacks: Tools like Argo Rollouts integrate with observability platforms (Prometheus/Datadog) to automatically detect issues and trigger rollbacks before user impact.
- Canary Deployments: Route a small percentage of traffic to a new version, gradually increasing it based on health checks and metrics.
- Blue-Green Deployments: Maintain two identical environments (blue and green) and instantly switch traffic between them for rapid, low-risk deployments and rollbacks.
A standard Kubernetes Deployment only supports basic Rolling Updates. If you deploy a bug, it will roll out to 100% of your users unless you manually stop it.
Progressive Delivery uses automation to reduce the "Blast Radius" of a bad release.
1. Canary Deployments
A Canary rollout sends a tiny fraction of traffic to the new version, analyzes its health, and then slowly increases the weight.
Argo Rollout: Canary
2. Argo Rollouts
The most popular tool for this is Argo Rollouts. It introduces a new resource kind: Rollout (a drop-in replacement for Deployment).
The Analysis Phase
Unlike standard K8s, Argo doesn't just check if the Pod is "Ready". It can talk to Prometheus or Datadog to ask:
- "Is the 500-error rate increasing?"
- "Is the average latency higher than v1?"
If the answer is YES, Argo automatically Rolls Back the version before it ever reaches 100% of users.
3. Blue-Green Deployments
Alternatively, you can use Blue-Green:
- Blue: The current live version.
- Green: The new version (idling, receiving no traffic).
- Switch: Once Green is fully tested, the Service/Ingress instantly flips 100% of traffic to Green.
- Instant Undo: If something is wrong, flip back to Blue.
Summary
Progressive Delivery turns "Deployment Day" into a non-event. Computers handle the risk, while humans just watch the dashboard.