Zero-Downtime CI/CD for 100K+ Daily Requests with Blue-Green Deployments

Building a Zero-Downtime CI/CD Pipeline: Blue-Green Deployments for 100K+ Daily Requests

This article details how a GitHub Actions + Docker + Blue-Green deployment strategy achieved zero downtime for a push notification service handling 100,000+ daily requests. The implementation avoids partial outages, ensures in-flight request completion, and enables instant rollbacks.

Why This Matters

Traditional deployment strategies like rolling updates or canary releases introduce partial downtime or infrastructure complexity. For services with long-running processes (e.g., BullMQ workers) or strict uptime requirements, Blue-Green deployments eliminate these risks. This approach guarantees zero downtime by maintaining two identical environments and switching traffic via Nginx in under 10ms. The cost of downtime for high-traffic systems can be catastrophic, making this method essential for production-grade reliability.

Key Insights

• “150+ deployments with 0 user-reported issues (6 months of production use)”
• “Multi-stage Dockerfiles reduce image size by 3.4x, improving security and build speed”
• “GitHub Actions used for CI/CD, enabling zero-maintenance pipelines with native GitHub integration”

Working Example

# Dockerfile: Multi-Stage Build
# ============= Stage 1: Build =============
FROM node:22-alpine AS builder
WORKDIR /app
COPY package*.json ./
RUN npm install
COPY . .
RUN npm run build
# ============= Stage 2: Runtime =============
FROM node:22-alpine AS runner
WORKDIR /app
COPY --from=builder /app/dist ./dist
COPY --from=builder /app/package*.json ./
RUN apk add --no-cache curl && npm install --only=production
EXPOSE 3002
CMD ["node", "dist/main"]

# docker-compose.yml: Health Checks for Blue-Green
services:
  messaging-blue:
    build: .
    env_file: .env
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost:3002/health/live"]
      interval: 10s
      timeout: 5s
      retries: 5
      start_period: 20s

# deploy-messaging.sh: Blue-Green Switch Logic
# ...
sudo sed -i "s/server localhost:3011;/server localhost:3012;/" /etc/nginx/conf.d/messaging.goodtv.co.kr.conf
sudo nginx -s reload
# ...

Practical Applications

• Use Case: High-traffic push notification service with 100K+ daily requests using Blue-Green deployments
• Pitfall: Overlooking health checks can lead to premature container switches and 502 errors during deployment

References:

• https://dev.to/sangwoo_rhie/zero-downtime-blue-green-deployment-with-github-actions-docker-multi-stage-builds-and-nginx-695