Container Orchestration Concepts

Why Orchestration?

Running a few containers manually is manageable. Running dozens or hundreds across multiple servers requires automated orchestration — scheduling, scaling, networking, and self-healing.

Key Concepts

• Scheduling — deciding which node runs which container
• Scaling — adding/removing container instances based on demand
• Service discovery — containers finding each other by name
• Load balancing — distributing traffic across container instances
• Self-healing — automatically restarting failed containers
• Rolling updates — deploying new versions without downtime

Docker Swarm (Simple)

# Initialize swarm
docker swarm init

# Create a service with 3 replicas
docker service create --name web --replicas 3 -p 80:80 nginx

# Scale up
docker service scale web=5

# Rolling update
docker service update --image nginx:latest web

Kubernetes (Enterprise)

# Deploy with kubectl
kubectl create deployment web --image=nginx --replicas=3
kubectl expose deployment web --port=80 --type=LoadBalancer
kubectl scale deployment web --replicas=5

When to Use What

• Docker Compose — single server, development, small production
• Docker Swarm — simple multi-node, built into Docker
• Kubernetes — complex multi-node, enterprise features, steep learning curve