deployment-strategies

name	deployment-strategies
description	Use when choosing or implementing a deployment strategy — provides Blue-Green, Canary, Rolling, and Feature Flag patterns with DORA metrics impact analysis. Extends the pipeline-designer agent. Also triggers on: re-run, update, revise, supplement.
metadata	{"category":"harness","harness":"20-cicd-pipeline","agent_type":"general-purpose"}

Deployment Strategies — Pipeline Deployment Pattern Reference

Reference for deployment strategies with DORA metrics impact analysis, rollback procedures, and implementation guides.

Strategy Comparison

Strategy	Downtime	Risk	Rollback Speed	Resource Cost	Best For
Recreate	Yes	High	Slow	Low	Non-critical, simple apps
Rolling	No	Medium	Medium	Low	Stateless apps, gradual rollout
Blue-Green	No	Low	Instant	High (2x infra)	Zero-downtime critical apps
Canary	No	Very Low	Fast	Medium	High-traffic apps, risk aversion
Feature Flags	No	Minimal	Instant	Low	Complex feature releases

Blue-Green Deployment

BLUE (current prod) → GREEN (new version)
Load balancer switch: blue → green
Rollback: switch back to blue (< 1 min)

GitHub Actions pattern:

- name: Deploy to Green
  run: |
    kubectl set image deployment/app-green app=${{ env.IMAGE_TAG }}
    kubectl rollout status deployment/app-green

- name: Switch Traffic to Green
  run: |
    kubectl patch service app-lb -p '{"spec":{"selector":{"slot":"green"}}}'
    echo "Traffic switched to green"

Canary Deployment

10% → 25% → 50% → 100% (with health checks at each step)
Rollback: route 100% back to stable

GitHub Actions pattern with manual approval gates:

- name: Canary 10%
  run: kubectl apply -f k8s/canary-10.yaml

- name: Wait for approval to increase to 25%
  uses: trstringer/manual-approval@v1
  with:
    secret: ${{ github.TOKEN }}
    approvers: ops-team
    minimum-approvals: 1

DORA Metrics Impact

Strategy	Deployment Frequency	Lead Time	MTTR	Change Failure Rate
Recreate	↓ (fear of downtime)	No change	↑ (slow rollback)	High
Rolling	→	No change	Medium	Medium
Blue-Green	↑ (no downtime fear)	↓ (fast verify)	↓ (instant rollback)	Low
Canary	↑↑ (safe to deploy more)	No change	↓↓ (catch early)	Very Low
Feature Flags	↑↑ (decouple deploy/release)	↓↓ (deploy anytime)	↓↓ (flag off)	Very Low

Rollback Procedures

Blue-Green Rollback

# Instant: switch load balancer back to blue
kubectl patch service app-lb -p '{"spec":{"selector":{"slot":"blue"}}}'

Canary Rollback

# Route all traffic back to stable
kubectl delete deployment app-canary

Feature Flag Rollback

# Disable flag (no deployment needed)
launchdarkly feature-flag update my-feature --enabled false