AutoScaling / Client / describe_load_balancers




This API operation is superseded by DescribeTrafficSources, which can describe multiple traffic sources types. We recommend using DescribeTrafficSources to simplify how you manage traffic sources. However, we continue to support DescribeLoadBalancers. You can use both the original DescribeLoadBalancers API operation and DescribeTrafficSources on the same Auto Scaling group.

Gets information about the load balancers for the specified Auto Scaling group.

This operation describes only Classic Load Balancers. If you have Application Load Balancers, Network Load Balancers, or Gateway Load Balancers, use the DescribeLoadBalancerTargetGroups API instead.

To determine the attachment status of the load balancer, use the State element in the response. When you attach a load balancer to an Auto Scaling group, the initial State value is Adding. The state transitions to Added after all Auto Scaling instances are registered with the load balancer. If Elastic Load Balancing health checks are enabled for the Auto Scaling group, the state transitions to InService after at least one Auto Scaling instance passes the health check. When the load balancer is in the InService state, Amazon EC2 Auto Scaling can terminate and replace any instances that are reported as unhealthy. If no registered instances pass the health checks, the load balancer doesn’t enter the InService state.

Load balancers also have an InService state if you attach them in the CreateAutoScalingGroup API call. If your load balancer state is InService, but it is not working properly, check the scaling activities by calling DescribeScalingActivities and take any corrective actions necessary.

For help with failed health checks, see Troubleshooting Amazon EC2 Auto Scaling: Health checks in the Amazon EC2 Auto Scaling User Guide. For more information, see Use Elastic Load Balancing to distribute traffic across the instances in your Auto Scaling group in the Amazon EC2 Auto Scaling User Guide.

See also: AWS API Documentation

Request Syntax

response = client.describe_load_balancers(
  • AutoScalingGroupName (string) –


    The name of the Auto Scaling group.

  • NextToken (string) – The token for the next set of items to return. (You received this token from a previous call.)

  • MaxRecords (integer) – The maximum number of items to return with this call. The default value is 100 and the maximum value is 100.

Return type:



Response Syntax

    'LoadBalancers': [
            'LoadBalancerName': 'string',
            'State': 'string'
    'NextToken': 'string'

Response Structure

  • (dict) –

    • LoadBalancers (list) –

      The load balancers.

      • (dict) –

        Describes the state of a Classic Load Balancer.

        • LoadBalancerName (string) –

          The name of the load balancer.

        • State (string) –

          One of the following load balancer states:

          • Adding - The Auto Scaling instances are being registered with the load balancer.

          • Added - All Auto Scaling instances are registered with the load balancer.

          • InService - At least one Auto Scaling instance passed an ELB health check.

          • Removing - The Auto Scaling instances are being deregistered from the load balancer. If connection draining is enabled, Elastic Load Balancing waits for in-flight requests to complete before deregistering the instances.

          • Removed - All Auto Scaling instances are deregistered from the load balancer.

    • NextToken (string) –

      A string that indicates that the response contains more items than can be returned in a single response. To receive additional items, specify this string for the NextToken value when requesting the next set of items. This value is null when there are no more items to return.



This example describes the load balancers attached to the specified Auto Scaling group.

response = client.describe_load_balancers(


Expected Output:

    'LoadBalancers': [
            'LoadBalancerName': 'my-load-balancer',
            'State': 'Added',
    'ResponseMetadata': {
        '...': '...',