ECS Networking and Load Balancing

Networking is fundamental to running containers in production. Your tasks need to receive traffic, communicate with each other, access databases, and connect to the internet — all securely. This lesson covers ECS networking modes, load balancer integration, service discovery, and network architecture patterns.

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ECS Network Modes

ECS supports several network modes, each with different trade-offs:

awsvpc Mode (Recommended)

Every task gets its own Elastic Network Interface (ENI) with a private IP address from your VPC. This is the default for Fargate and the recommended mode for EC2 as well.

VPC (10.0.0.0/16)
├── Subnet A (10.0.1.0/24)
│   ├── Task 1 — ENI → 10.0.1.15
│   └── Task 2 — ENI → 10.0.1.22
└── Subnet B (10.0.2.0/24)
    ├── Task 3 — ENI → 10.0.2.8
    └── Task 4 — ENI → 10.0.2.31

Advantages:

• Each task has its own security group
• Full VPC networking features (flow logs, NACLs)
• Simplified port mapping — no port conflicts
• Same networking model as EC2 instances

Consideration: Each ENI consumes an IP address from your subnet. For large deployments, ensure your subnets have enough IP addresses.

bridge Mode (EC2 Only)