Target groups for your Gateway Load Balancers - Elastic Load Balancing

Target groups for your Gateway Load Balancers

Each target group is used to route requests to one or more registered targets. When you create a listener, you specify a target group for its default action. Traffic is forwarded to the target group that's specified in the listener rule. You can create different target groups for different types of requests.

You define health check settings for your Gateway Load Balancer on a per target group basis. Each target group uses the default health check settings, unless you override them when you create the target group or modify them later on. After you specify a target group in a rule for a listener, the Gateway Load Balancer continually monitors the health of all targets registered with the target group that are in an Availability Zone enabled for the Gateway Load Balancer. The Gateway Load Balancer routes requests to the registered targets that are healthy. For more information, see Health checks for your target groups.

Routing configuration

Target groups for Gateway Load Balancers support the following protocol and port:

  • Protocol: GENEVE

  • Port: 6081

Target type

When you create a target group, you specify its target type, which determines how you specify its targets. After you create a target group, you cannot change its target type.

The following are the possible target types:

instance

The targets are specified by instance ID.

ip

The targets are specified by IP address.

When the target type is ip, you can specify IP addresses from one of the following CIDR blocks:

  • The subnets of the VPC for the target group

  • 10.0.0.0/8 (RFC 1918)

  • 100.64.0.0/10 (RFC 6598)

  • 172.16.0.0/12 (RFC 1918)

  • 192.168.0.0/16 (RFC 1918)

Important

You can't specify publicly routable IP addresses.

Registered targets

Your Gateway Load Balancer serves as a single point of contact for clients, and distributes incoming traffic across its healthy registered targets. Each target group must have at least one registered target in each Availability Zone that is enabled for the Gateway Load Balancer. You can register each target with one or more target groups.

If demand increases, you can register additional targets with one or more target groups in order to handle the demand. The Gateway Load Balancer starts routing traffic to a newly registered target as soon as the registration process completes.

If demand decreases, or you need to service your targets, you can deregister targets from your target groups. Deregistering a target removes it from your target group, but does not affect the target otherwise. The Gateway Load Balancer stops routing traffic to a target as soon as it is deregistered. The target enters the draining state until in-flight requests have completed. You can register the target with the target group again when you are ready for it to resume receiving traffic.

Target group attributes

The following are the target group attributes:

deregistration_delay.timeout_seconds

The amount of time for Elastic Load Balancing to wait before changing the state of a deregistering target from draining to unused. The range is 0-3600 seconds. The default value is 300 seconds.

Deregistration delay

When you deregister an instance, the Gateway Load Balancer stops creating new connections to the instance. The Gateway Load Balancer uses connection draining to ensure that in-flight traffic completes on the existing connections. If the deregistered instance stays healthy and an existing connection is not idle, the Gateway Load Balancer can continue to send traffic to the instance. To ensure that existing connections are closed, you can verify that the instance is unhealthy before you deregister it, or you can periodically close client connections.

The initial state of a deregistering target is draining. By default, the Gateway Load Balancer changes the state of a deregistering target to unused after 300 seconds. To change the amount of time that the Gateway Load Balancer waits before changing the state of a deregistering target to unused, update the deregistration delay value. We recommend that you specify a value of at least 120 seconds to ensure that requests are completed.

New console

To update the deregistration delay value using the new console

  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.

  2. On the navigation pane, under LOAD BALANCING, choose Target Groups.

  3. Choose the name of the target group to open its details page.

  4. On the Group details page, in the Attributes section, choose Edit.

  5. On the Edit attributes page, change the value of Deregistration delay as needed.

  6. Choose Save changes.

Old console

To update the deregistration delay value using the old console

  1. Open the Amazon EC2 console at https://console.aws.amazon.com/ec2/.

  2. On the navigation pane, under LOAD BALANCING, choose Target Groups.

  3. Select the target group.

  4. Choose Description, Edit attributes.

  5. Change the value of Deregistration delay as needed, and then choose Save.

To update the deregistration delay value using the AWS CLI

Use the modify-target-group-attributes command.