Update the target group health settings for your Network Load Balancer - Elastic Load Balancing
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Update the target group health settings for your Network Load Balancer

By default, Network Load Balancers monitor the health of targets and route requests to healthy targets. However, if the load balancer doesn't have enough healthy targets, it automatically sends traffic to all registered targets (fail open). You can modify the target group health settings for your target group to define the thresholds for DNS failover and routing failover. For more information, see Target group health.

Console
To update the target group health settings

  1. Open the Amazon EC2 console at https://console.amazonaws.cn/ec2/.

  2. In 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 Attributes tab, choose Edit.

  5. Expand Target group health requirements.

  6. For Configuration type, we recommend that you choose Unified configuration, which sets the same threshold for both DNS failover and routing failover.

  7. For Healthy state requirements, do one of the following:

    • Choose Minimum healthy target count, and then enter a number from 1 to the maximum number of targets for your target group.

    • Choose Minimum healthy target percentage, and then enter a number from 1 to 100.

  8. The informational text indicates whether cross-zone load balancing is enabled for the target group. If cross-zone load balancing is disabled, you can enable it to ensure that you have enough capacity. Under Target selection configuration, update Cross-zone load balancing.

    The following text indicates that cross-zone load balancing is disabled:

    Healthy state requirements apply to each zone independently.

    The following text indicates that cross-zone load balancing is enabled:

    Healthy state requirements apply to the total targets across all applicable zones.

  9. Choose Save changes.

Amazon CLI
To update the target group health settings

Use the modify-target-group-attributes command. The following example sets the healthy threshold for both unhealthy state actions to 50%.

aws elbv2 modify-target-group-attributes \
    --target-group-arn target-group-arn \
    --attributes \
      "Key=target_group_health.dns_failover.minimum_healthy_targets.percentage,Value=50" \
      "Key=target_group_health.unhealthy_state_routing.minimum_healthy_targets.percentage,Value=50"
CloudFormation
To modify target group health settings

Update the AWS::ElasticLoadBalancingV2::TargetGroup resource. The following example sets the healthy threshold for both unhealthy state actions to 50%.

Resources:
  myTargetGroup:
    Type: 'AWS::ElasticLoadBalancingV2::TargetGroup'
    Properties:
      Name: my-target-group
      Protocol: TCP
      Port: 80
      TargetType: ip
      VpcId: !Ref myVPC
      TargetGroupAttributes: 
        - Key: "target_group_health.dns_failover.minimum_healthy_targets.percentage"
          Value: "50"
        - Key: "target_group_health.unhealthy_state_routing.minimum_healthy_targets.percentage"
          Value: "50"