Posted On: Feb 8, 2021

Application Load Balancer (ALB) now supports Application-based cookie stickiness. This new feature helps customers ensure that clients connect to the same load balancer target for the duration of their session using application cookies. This enables customers to achieve a consistent client-server experience with greater controls such as the flexibility to set custom cookie names and criteria for client-target stickiness within a target group.

Prior to this launch, ALB supported duration-based stickiness to maintain client-server affinity with a cookie generated automatically by the ALB. With this launch, customers can now choose to use a custom application cookie set at the target group level to enforce stickiness between client and targets. It gives the user additional controls around the duration for which stickiness is enabled. It also allows users to maintain stickiness across load balancers that are chained together.

To use this feature on your ALB, choose Application-based stickiness as the stickiness type for your target group. Once enabled, ALB will pick the target for the first request based on the chosen load-balancing algorithm and use the cookie set by the target to ensure that the subsequent requests from the client remain stuck to the same healthy target. The ALB uses active health checks to monitor the health of targets and re-establishes stickiness with new healthy targets based on the chosen load-balancing algorithm in case of unhealthy targets.

Application Cookie Stickiness is available for existing and new ALBs at no extra charge in all AWS Regions. To learn more, please refer to the ALB documentation.