ALB

ALB distributes incoming traffic across multiple targets (see concepts below) in one or more AZ. It provides layer 7 (HTTP/HTTPS) load balancing and SSL offload with host- and path-based routing, sticky sessions, and SNI.

Note that whilst ALBs do not preserve source IPs, they do send the X-Forwarded-For, X-Forwarded-Proto, and X-Forwarded-Port proxy headers.

Concepts

• Listeners capture incoming traffic.
  • Optionally, they may also authenticate users through OIDC, or social or corporate IdPs Cognito.
• Target Groups represent sets of backends to forward the traffic to for processing.
• Health checks verify that a target within a Target Group is ready to serve traffic.
• Rules allow selectively matching requests for forwarding to Target Groups, redirecting, requiring authentication or sending a static response.
• Conditions allow matching traffic meeting configured criteria: Host header or request path.

Targets

Target groups can point at:

• EC2 instances, either manually or via Auto Scaling.
• IP addresses, either on AWS or external.
• Lambda functions
• ECS tasks

[ALB] Application Load Balancer [AWS] Amazon Web Services [AZ] Availability Zone [EC2]: Elastic Container Cloud

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Backlinks

• ELB (public)
• WAF (public)
• Classic (public)
• NLB (public)