Listener rules for your Application Load Balancer - Elastic Load Balancing

Listener rules for your Application Load Balancer

The listener rules for your Application Load Balancer determine how it routes requests to targets. When a listener receives a request, it evaluates the request against each rule in priority order, starting with the lowest numbered rule. Each rule includes conditions to be met and the actions to perform when the conditions for the rule are met. This flexible routing mechanism allows you to implement sophisticated traffic distribution patterns, support multiple applications or microservices behind a single load balancer, and customize request handling based on your application's specific requirements.

Rule basics

  • Each rule consists of a priority, one or more actions, and one or more conditions.

  • Each rule action has a type and the information required to perform the action.

  • Each rule condition has a type and the information required to evaluate the condition.

  • When you create a listener, you define actions for the default rule. The default rule can't have conditions. If none of the conditions for the other rules are met, then the action for the default rule is performed.

  • Rules are evaluated in priority order, from the lowest value to the highest value. The default rule is evaluated last. You can't change the priority of the default rule.

  • Each rule must include exactly one of the following actions: forward, redirect, or fixed-response, and it must be the last action to be performed.

  • Each rule other than the default rule can optionally include one of the following conditions: host-header, http-request-method, path-pattern, and source-ip. It can also optionally include one or both of the following conditions: http-header and query-string.

  • You can specify up to three comparison strings per condition and up to five per rule.

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