Automatic Target Weights in Application Load Balancer optimizes traffic distribution to backend targets based on their health, improving application availability by reducing load on impaired targets until they recover.

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<p>The article discusses a new feature called Automatic Target Weights (ATW) for the Application Load Balancer (ALB) service on AWS. ATW uses a new routing algorithm to optimize the amount of traffic sent to each target based on health information.</p>
<p>Specifically, the article covers:</p>
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<li>ATW adjusts traffic based on implicit health information like 5XX errors and connection errors, in addition to health checks</li>
<li>It detects and reduces traffic to anomalous targets that are partially failed, even if health checks pass</li>
<li>ATW can surface anomalous targets using CloudWatch metrics or automatically mitigate impact by reducing traffic</li>
<li>If targets recover, ALB gradually increases traffic back to normal levels</li>
<li>ATW is enabled by configuring the "weighted random" load balancing algorithm</li>
<li>It is available in all commercial AWS regions and AWS GovCloud (US) regions</li>
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Application Load Balancer increases application availability with Automatic Target Weights

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