ELB team is happy to announce that we just launched a new Target Failover feature that provides an option to define flow handling behavior for AWS Gateway Load Balancer. Using this option, customers can now rebalance existing flows to a healthy target, when the target fails or deregisters. This helps reduce failover time when a target becomes unhealthy, and also allows customers to gracefully patch or upgrade the appliances during maintenance windows.
Launch Details:
This feature uses the existing ELB API/Console and provides new attributes to specify the flow handling behavior. You can use the existing modify-target-group-attributes API to define flow handling behavior using the two new attributes target_failover.on_unhealthy and target_failover.on_deregistration.
This feature does not change the default behavior and existing GWLBs are not affected.
The feature is available using API and AWS Console.
The feature is available in all commercial, GovCloud, and China regions. It will be deployed in ADC regions at a later date based on demand.
Customers should evaluate the effect of enabling this feature on availability and check with their third-party appliance provider documentation.
AWS appliance partners should consider taking following actions - (a) Partners should validate whether rebalancing existing flows to healthy target has implications on their appliance as it will start receiving the flow midway, i.e. without getting the TCP SYN. (b) Update public documentation on how this feature will affect their appliance. (c) Partner may use this capability to improve stateful flow handling on their appliances.