Components of a load balancers

Components of a AWS load balancers

• Listener
• Rules
• Actions

Listener

A process that checks for incoming traffic based on your configuration and reacts based on the rules

• Listens on a specific port (e.g., 80 or 443) for incoming traffic.
• Configurations
  • Protocol
  • Port
  • TLS termination

Each listener must have at least one default rule.

https://docs.aws.amazon.com/elasticloadbalancing/latest/application/load-balancer-listeners.html#listener-rules

Rules

• Rules will get attached to a load balancer
• Each rule has a priority and priority determines the order in which rules get executed.
• Each rule can have a target group

Action

• https://docs.aws.amazon.com/elasticloadbalancing/latest/application/load-balancer-listeners.html#rule-action-types
• redirect, forward, fixed response…
• A rule can have a list of actions. These are executed in order.

// Top to bottom
// valid
{
  "Actions": [
    { "Type": "authenticate-cognito", ... },
    { "Type": "forward", ... }
  ]
}
 
// invalid
{
  "Actions": [
    { "Type": "redirect", ... },
    { "Type": "forward", ... }
  ]
}
 

Target group

• targets in the target group can be in different AZs