Listener Rule Extension

This module provides an ECS Service Extension that registers your service with an application load balancer by way of listener rules.

Rules added via this extension are automatically prioritized in the load balancer by default. The automatic prioritization starts at a number (default: 1) and increases by a step value (default: 5) for each rule added that doesn't have an explicit priority.

Get Started

To add this module to your project, install @wheatstalk/ecs-service-extension-listener-rules with either yarn or npm:

# Yarn
yarn add @wheatstalk/ecs-service-extension-listener-rules

# NPM install
npm install @wheatstalk/ecs-service-extension-listener-rules

Example Usage

You may expose your service by adding listener rules to an existing Application Load Balancer listener. To accomplish this, you must set up your service description and then add a new ListenerRulesExtension:

serviceDescription.add(new ListenerRulesExtension({
  listener, // Your IApplicationListener
  rules: [
    // Serve requests for 'www.example.com'
    ListenerRulesExtension.hostHeader('www.example.com'),
    // Redirect '*.example.com' to 'www.example.com'
    ListenerRulesExtension.hostHeaderRedirect('*.example.com', {
      host: 'www.example.com',
    }),
    // Serve requests on a subpath '/somepath'
    ListenerRulesExtension.pathPattern('/somepath'),
    // Redirect the path '/redirect' to 'aws.amazon.com'
    ListenerRulesExtension.pathPatternRedirect('/redirect', {
      host: 'aws.amazon.com',
    }),
  ],
}));

Choosing Priorities

If you have specific requirements for ALB priorities, you may set the rule priorities in either of two ways:

• Provide a priorityStart to the extension props
• Provide a priority option for a specific rule

Priority examples

serviceDescription.add(new ListenerRulesExtension({
  listener, // Your IApplicationListener
  priorityStart: 10000, // Starting priority number (default is `1`)
  priorityStep: 5, // Step size for automatic numbering (default is `5`)
  rules: [
    // Serve requests for 'www.example.com' - will be priority 10000
    ListenerRulesExtension.hostHeader('www.example.com'),
    // Register the wildcard host header with the priority 39999
    ListenerRulesExtension.hostHeader('*.example.com', {
      priority: 39999,
    }),
  ],
}));

Note on JSII Support

This module won't support JSII until ECS Service Extensions introduces support for JSII.