Progressive Delivery — Canary, Blue-Green and Feature Flags

DevOps Intermediate

Progressive Delivery — Canary, Blue-Green and Feature Flags¶

Progressive DeliveryCanaryBlue-GreenFeature Flags 6 min read

Progressive delivery strategies. Canary with metrics, blue-green with rollback and feature flags.

Canary with Automated Analysis¶

apiVersion: flagger.app/v1beta1
kind: Canary
metadata:
  name: api-server
spec:
  targetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: api-server
  analysis:
    interval: 1m
    threshold: 5
    maxWeight: 50
    stepWeight: 10
    metrics:
      - name: request-success-rate
        thresholdRange:
          min: 99
        interval: 1m
      - name: request-duration
        thresholdRange:
          max: 500
        interval: 1m

Blue-Green with Argo Rollouts¶

apiVersion: argoproj.io/v1alpha1
kind: Rollout
metadata:
  name: api-server
spec:
  replicas: 5
  strategy:
    blueGreen:
      activeService: api-active
      previewService: api-preview
      autoPromotionEnabled: false
      prePromotionAnalysis:
        templates:
          - templateName: smoke-tests
      scaleDownDelaySeconds: 300

Feature Flags¶

from unleash_client import UnleashClient

client = UnleashClient("http://unleash:4242/api", "app")
client.initialize_client()

if client.is_enabled("new-checkout-flow", {"userId": user.id}):
    return new_checkout(order)
else:
    return legacy_checkout(order)

# Strategies:
# - Boolean toggle (on/off)
# - Percentage rollout (10% → 50% → 100%)
# - User segment (beta users, region)
# - A/B testing

When to Use What¶

• Canary — infrastructure changes, new service versions
• Blue-Green — database migrations, breaking changes
• Feature Flags — business logic, A/B tests, runtime control
• Combination — canary + feature flag = maximum control

Summary¶

Progressive delivery minimizes the blast radius of changes. Combine canary, blue-green and feature flags as needed.

Need Help with Implementation?¶

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