Posted On: Nov 28, 2022
We are excited to announce four new Elastic Load Balancing capabilities to further improve the availability of your applications. AWS provides multiple building blocks, like Regions and Availability Zones, so that you can design your applications to isolate your applications from different types of failures. Starting today, we are providing additional features that allow you to define how you want your applications to behave when failures occur as well as a feature to help you recover faster. These new capabilities include:
Application Load Balancer (ALB) Cross Zone Off: ALB now has the ability to turn off cross zone load balancing, similar to the existing capability on NLB. When enabled, ALB routes traffic to targets in the same Availability Zone (AZ) as the load balancer nodes. This capability enables customers to maintain zonal isolation of their application stacks, while still providing redundancy across multiple AZs. For details, see the ALB cross zone off feature documentation here.
Network Load Balancer (NLB) Health Check Improvements: NLB allows customers to define health check intervals, specify HTTP response codes that determine target health, and configure the number of consecutive health check responses before a target is either health or unhealthy. For details, see the NLB health check documentation here.
ALB and NLB Minimum Healthy Targets: Customers can now configure a threshold for the minimum number or percentage of healthy targets for ALB and NLB in an AZ. When the healthy target capacity drops below the specified threshold, the load balancer automatically stops routing to targets in the impaired AZ. For details, see the documentation here for ALB and here for NLB.
Zonal Shift for ALB and NLB [Preview]: Using Amazon Route 53 Application Recovery Controller’s zonal shift feature, you can recover from gray failures, like bad application deployments, by routing traffic away from a single impaired AZ. This feature is ideal for zonally architected applications using ALBs and NLBs that have cross-zone load balancing turned off. For details, read the launch blog, or see the Zonal Shift section of the documentation here.
There is no additional charge for using these features. ALB Cross Zone Off, NLB health check improvements, and ALB/NLB Min Healthy Targets features are now available in all commercial AWS Regions, and AWS GovCloud (US) Regions. The ALB and NLB zonal shift feature is available in preview in the AWS US West (Oregon), US East (Northern Virginia), US East (Ohio), Europe (Ireland), Europe (Frankfurt), Europe (Stockholm), Asia Pacific (Tokyo), Asia Pacific (Sydney), and Asia Pacific (Jakarta) Regions.
12/1/2022: In paragraph 4 the sentence "When the threshold is exceeded, the load balancer automatically stops routing to targets in the impaired AZ" is inaccurate so its been changed to "When the healthy target capacity drops below the specified threshold, the load balancer automatically stops routing to targets in the impaired AZ"