There are more AWS SDK examples available in the [AWS Doc SDK Examples](https://github.com/awsdocs/aws-doc-sdk-examples) GitHub repo.
# Use `AttachLoadBalancerTargetGroups` with an AWS SDK or CLI
The following code examples show how to use `AttachLoadBalancerTargetGroups`.
Action examples are code excerpts from larger programs and must be run in context. You can see this action in context in the following code example:
+ [Build and manage a resilient service](auto-scaling_example_cross_ResilientService_section.md)
------
#### [ .NET ]
**SDK for .NET**
There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/dotnetv3/cross-service/ResilientService/AutoScalerActions#code-examples).
```
///
/// Attaches an Elastic Load Balancing (ELB) target group to this EC2 Auto Scaling group.
/// The
///
/// The name of the Auto Scaling group.
/// The Arn for the target group.
/// Async task.
public async Task AttachLoadBalancerToGroup(string autoScalingGroupName, string targetGroupArn)
{
await _amazonAutoScaling.AttachLoadBalancerTargetGroupsAsync(
new AttachLoadBalancerTargetGroupsRequest()
{
AutoScalingGroupName = autoScalingGroupName,
TargetGroupARNs = new List() { targetGroupArn }
});
}
```
+ For API details, see [AttachLoadBalancerTargetGroups](https://docs.aws.amazon.com/goto/DotNetSDKV3/autoscaling-2011-01-01/AttachLoadBalancerTargetGroups) in *AWS SDK for .NET API Reference*.
------
#### [ CLI ]
**AWS CLI**
**To attach a target group to an Auto Scaling group**
This example attaches the specified target group to the specified Auto Scaling group.
```
aws autoscaling attach-load-balancer-target-groups \
--auto-scaling-group-name my-asg \
--target-group-arns arn:aws:elasticloadbalancing:us-west-2:123456789012:targetgroup/my-targets/73e2d6bc24d8a067
```
This command produces no output.
For more information, see [Elastic Load Balancing and Amazon EC2 Auto Scaling](https://docs.aws.amazon.com/autoscaling/ec2/userguide/autoscaling-load-balancer.html) in the *Amazon EC2 Auto Scaling User Guide*.
+ For API details, see [AttachLoadBalancerTargetGroups](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/autoscaling/attach-load-balancer-target-groups.html) in *AWS CLI Command Reference*.
------
#### [ JavaScript ]
**SDK for JavaScript (v3)**
There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/cross-services/wkflw-resilient-service#code-examples).
```
const client = new AutoScalingClient({});
await client.send(
new AttachLoadBalancerTargetGroupsCommand({
AutoScalingGroupName: NAMES.autoScalingGroupName,
TargetGroupARNs: [state.targetGroupArn],
}),
);
```
+ For API details, see [AttachLoadBalancerTargetGroups](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/auto-scaling/command/AttachLoadBalancerTargetGroupsCommand) in *AWS SDK for JavaScript API Reference*.
------
#### [ Python ]
**SDK for Python (Boto3)**
There's more on GitHub. Find the complete example and learn how to set up and run in the [AWS Code Examples Repository](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/python/example_code/auto-scaling#code-examples).
```
class AutoScalingWrapper:
"""
Encapsulates Amazon EC2 Auto Scaling and EC2 management actions.
"""
def __init__(
self,
resource_prefix: str,
inst_type: str,
ami_param: str,
autoscaling_client: boto3.client,
ec2_client: boto3.client,
ssm_client: boto3.client,
iam_client: boto3.client,
):
"""
Initializes the AutoScaler class with the necessary parameters.
:param resource_prefix: The prefix for naming AWS resources that are created by this class.
:param inst_type: The type of EC2 instance to create, such as t3.micro.
:param ami_param: The Systems Manager parameter used to look up the AMI that is created.
:param autoscaling_client: A Boto3 EC2 Auto Scaling client.
:param ec2_client: A Boto3 EC2 client.
:param ssm_client: A Boto3 Systems Manager client.
:param iam_client: A Boto3 IAM client.
"""
self.inst_type = inst_type
self.ami_param = ami_param
self.autoscaling_client = autoscaling_client
self.ec2_client = ec2_client
self.ssm_client = ssm_client
self.iam_client = iam_client
sts_client = boto3.client("sts")
self.account_id = sts_client.get_caller_identity()["Account"]
self.key_pair_name = f"{resource_prefix}-key-pair"
self.launch_template_name = f"{resource_prefix}-template-"
self.group_name = f"{resource_prefix}-group"
# Happy path
self.instance_policy_name = f"{resource_prefix}-pol"
self.instance_role_name = f"{resource_prefix}-role"
self.instance_profile_name = f"{resource_prefix}-prof"
# Failure mode
self.bad_creds_policy_name = f"{resource_prefix}-bc-pol"
self.bad_creds_role_name = f"{resource_prefix}-bc-role"
self.bad_creds_profile_name = f"{resource_prefix}-bc-prof"
def attach_load_balancer_target_group(
self, lb_target_group: Dict[str, Any]
) -> None:
"""
Attaches an Elastic Load Balancing (ELB) target group to this EC2 Auto Scaling group.
The target group specifies how the load balancer forwards requests to the instances
in the group.
:param lb_target_group: Data about the ELB target group to attach.
"""
try:
self.autoscaling_client.attach_load_balancer_target_groups(
AutoScalingGroupName=self.group_name,
TargetGroupARNs=[lb_target_group["TargetGroupArn"]],
)
log.info(
"Attached load balancer target group %s to auto scaling group %s.",
lb_target_group["TargetGroupName"],
self.group_name,
)
except ClientError as err:
error_code = err.response["Error"]["Code"]
log.error(
f"Failed to attach load balancer target group '{lb_target_group['TargetGroupName']}'."
)
if error_code == "ResourceContentionFault":
log.error(
"The request failed due to a resource contention issue. "
"Ensure that no conflicting operations are being performed on the resource."
)
elif error_code == "ServiceLinkedRoleFailure":
log.error(
"The operation failed because the service-linked role is not ready or does not exist. "
"Check that the service-linked role exists and is correctly configured."
)
log.error(f"Full error:\n\t{err}")
```
+ For API details, see [AttachLoadBalancerTargetGroups](https://docs.aws.amazon.com/goto/boto3/autoscaling-2011-01-01/AttachLoadBalancerTargetGroups) in *AWS SDK for Python (Boto3) API Reference*.
------