How to Disable an Availability Zone from a Load Balanced Application

Amazon Elastic Load Balancing: 2009-05-15

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How to Disable an Availability Zone from a Load Balanced Application

In this example, you disable the Availability Zone us-east-1a for your EC2 application.

This scenario assumes that you have an HTTP LoadBalancer enabled in Availability Zones us-east-1a and us-east-1b.

You disable the Availability Zone for the LoadBalancer first, then give the instances time to go into the OutOfService state before deregistering them from your LoadBalancer.

[Note] Note
Your LoadBalancer always distributes traffic to all the enabled Availability Zones. If all the instances in an Availability Zone are deregistered or unhealthy before that Availability Zone is disabled for the LoadBalancer, all requests sent to that Availability Zone will fail until DisableAvailabilityZonesForLoadBalancer calls for that Availability Zone.

API Example

To disable an availability zone from a Load Balanced Application

  1. Call DisableAvailabilityZonesForLoadBalancer with the following parameters:

    • LoadBalancerName = MyLoadBalancer

    • Availability Zones = us-east-1a

    The operation returns the updated list of Availability Zones enabled for your LoadBalancer.

  2. Call DescribeInstanceHealth with the following parameters. You have to wait until all of the instances in the disabled Availability Zones are in the OutOfService state.

    • LoadBalancerName = MyLoadBalancer

    • Instances = i-4f8cf126, i-0bb7ca62

  3. Call DeregisterInstancesFromLoadBalancer with the following parameters:

    • LoadBalancerName = MyLoadBalancer

    • Instances = i-4f8cf126, i-0bb7ca62

Command Line Tools Example

To disable an availability zone from a Load Balanced Application

  1. Use the elb-disable-zones-for-lb command as in the following example.

    PROMPT> elb-disable-zones-for-lb  MyLoadBalancer  --headers --availability-zones us-east-1a

    Elastic Load Balancing returns the following:

    AVAILABILITY_ZONES  AVAILABILITY-ZONES
AVAILABILITY_ZONES  us-east-1b

  2. Use the elb-describe-instance-health command as in the following example.

    PROMPT> elb-describe-instance-health  MyLoadBalancer  --headers --instances i-4f8cf126,i-0bb7ca62

    Elastic Load Balancing returns the following:

    INSTANCE  INSTANCE-ID STATE
INSTANCE i-4f8cf126 OutOfService
INSTANCE i-0bb7ca62 OutOfService
    [Note] Note
    Only when the instances are in the OutOfService state can you progress to the next step.

  3. Use the elb-deregister-instances-from-lb command as in the following example.

    PROMPT> elb-deregister-instances-from-lb  MyLoadBalancer  --headers --instances i-4f8cf126,i-0bb7ca62

    Elastic Load Balancing returns the following:

    INSTANCE  INSTANCE-ID
INSTANCE i-3a8cf324
INSTANCE i-2603ca33

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