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Application Load Balancer

A load balancer that functions at the application layer (Layer 7), allowing for advanced routing based on HTTP headers and paths.

AbbreviationALB
Categorycloud

Overview

An Application Load Balancer (ALB) operates at the seventh layer of the Open Systems Interconnection (OSI) model. After the load balancer receives a request, it evaluates the listener rules in priority order to determine which rule to apply, and then selects a target from the target group for the rule action.

Key Features

  • Path-based Routing: Route traffic based on the URL path (e.g., /api vs /images).
  • Host-based Routing: Route traffic based on the host header (e.g., app.example.com vs api.example.com).
  • Support for Containers: Ideal for microservices and container-based applications (e.g., Amazon ECS).
  • WebSockets Support: Allows for long-lived TCP connections.

Use Cases

  • Microservices architectures.
  • Modern web applications requiring granular traffic control.
  • Applications using HTTP/2 or gRPC.

Related Terms

Elastic Load BalancingNetwork Load Balancer