1. Log in to the AWS Management Console and navigate to the EC2 dashboard.
2. Click on the Load Balancers option in the navigation pane.
3. Select the ELB that you want to remediate and click on the Edit button.
4. In the Availability Zones section, select the AZs that are not currently being used by the ELB.
5. Click on the Add button to add the selected AZs to the ELB.
6. Once the AZs have been added, click on the Remove button next to any AZs that are currently being used by the ELB but are not evenly distributed.
7. Click on the Save button to save the changes.
8. Verify that the ELB is now evenly distributed over all selected AZs by checking the Availability Zones section.
9. Repeat the above steps for any other ELBs that are not evenly distributed over AZs.

​

1. First, check the availability zones in which the ELB is currently running using the following command:

aws elb describe-load-balancers --load-balancer-name <ELB-Name> --query 'LoadBalancerDescriptions[].AvailabilityZones'

2. If the ELB is not evenly distributed over the AZs, then you need to modify the ELB configuration to distribute it evenly over the AZs. You can use the following command to modify the ELB configuration:

aws elb modify-load-balancer-attributes --load-balancer-name <ELB-Name> --load-balancer-attributes '{"CrossZoneLoadBalancing":{"Enabled":true}}'

3. Once the modification is done, you can verify that the ELB is now evenly distributed over all AZs by running the command in step 1 again.

1. Get a list of all the Elastic Load Balancers (ELBs) in your AWS account using the boto3 library.

import boto3

elb_client = boto3.client('elbv2')
elbs = elb_client.describe_load_balancers()['LoadBalancers']

2. For each ELB, get the list of Availability Zones (AZs) it is currently deployed in.

for elb in elbs:
    azs = elb_client.describe_load_balancer_attributes(LoadBalancerArn=elb['LoadBalancerArn'])['Attributes'][0]['Value'].split(',')

3. Check if the number of AZs the ELB is deployed in is less than the total number of AZs available in the region.

    if len(azs) < len(elb_client.describe_account_attributes(AttributeNames=['supported-availability-zones'])['AccountAttributes'][0]['AttributeValues']):

4. If the number of AZs is less than the total number of AZs available in the region, evenly distribute the ELB across all the AZs.

        new_azs = elb_client.describe_account_attributes(AttributeNames=['supported-availability-zones'])['AccountAttributes'][0]['AttributeValues']
        elb_client.modify_load_balancer_attributes(LoadBalancerArn=elb['LoadBalancerArn'], Attributes=[{'Key': 'AvailabilityZones', 'Value': ','.join(new_azs)}])

5. Once you have updated all the ELBs, verify that they are now evenly distributed across all the AZs in the region.

resource "aws_elb" "THIS_LOAD_BALANCER" {
  name               = "ELB_NAME"        # replace with the CLB name
  subnets            = [SUBNET_IDS]      # replace with your subnet IDs
  security_groups    = [SECURITY_GROUP_IDS]
  availability_zones = [AVAILABILITY_ZONES]

  # Enable cross-zone load balancing (matches the aws elb modify-load-balancer-attributes CLI)
  cross_zone_load_balancing {
    enabled = true
  }

  listener {
    instance_port     = 80
    instance_protocol = "http"
    lb_port           = 80
    lb_protocol       = "http"
  }

  instances = [INSTANCE_IDS]             # distribution across AZs must be fixed manually
}

• ~ aws_elb.THIS_LOAD_BALANCER
  • cross_zone_load_balancing.enabled: "false" => "true"