Chapter 16: Deployment & Operations Patterns

Metadata Card

Prerequisites: Chapter 14 (Microservices Patterns)
Estimated Time: 40 minutes
Core Difficulty: Intermediate
Completion Milestone: Understand common deployment strategies and release patterns

Your Progress

Engines are running, data is consistent. But every release requires 30 seconds of pipeline downtime — users see "System under maintenance." One time you misconfigured a pipe parameter, bringing down the entire production line.

You're afraid to upgrade, but the workshop master wants 20 iterations a day.

You need a technique to swap parts without stopping the machine. Your Task

Blue/Green, Canary, Feature Flags, Sidecar, Ambassador — patterns for zero-downtime deployment.

Required reading: Blue/Green, Canary, Feature Flags Selective: Sidecar, Ambassador Advanced: Chaos Engineering basics

First Layer: Blue/Green Deployment

Two identical environments. Blue runs current version (production). Green runs new version. Switch traffic instantly.

bash

# Switch to green
sed -i 's/server green.*/server green:8080 weight=1;/' nginx.conf
nginx -s reload
# Rollback: one command

Second Layer: Canary Release

Gradually shift traffic. Start with 1%, observe, then 5%, 20%, 100%. Requires monitoring comparison between canary and baseline.

Third Layer: Feature Flags

Control feature enablement through code conditions, not deployments. Allows progressive rollouts, A/B testing, instant rollback.

java

if (featureFlags.isEnabled("new-scoring-algorithm")) {
    return newAlgorithm(match);
}
return oldAlgorithm(match);

Fourth Layer: Sidecar & Ambassador

Sidecar: a helper container running alongside the main container (log collector, monitoring agent). Ambassador: a network proxy sidecar handling retry, timeout, circuit breaking.

Common Pitfalls: Blue/Green double infrastructure cost, canary without automated success/failure criteria, feature flag accumulation, no instant rollback capability.

Traveler's Notes

Deployment patterns control the riskiest operation — code changes. Blue/Green enables instant switching, Canary provides brakes while moving, Feature Flags decouple deployment from enablement, Sidecar/Ambassador put infrastructure capability beside your service.

Next: Event-Driven Architecture (Chapter 17).