There are more AWS SDK examples available in the [AWS Doc SDK Examples](https://github.com/awsdocs/aws-doc-sdk-examples) GitHub repo.
# Use `DescribeTargetHealth` with an AWS SDK or CLI
The following code examples show how to use `DescribeTargetHealth`.
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 examples:
+ [Build and manage a resilient service](elastic-load-balancing-v2_example_cross_ResilientService_section.md)
+ [Getting started with Elastic Load Balancing](elastic-load-balancing-v2_example_elastic_load_balancing_v2_GettingStarted_058_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/ElasticLoadBalancerActions#code-examples).
```
///
/// Get the target health for a group by name.
///
/// The name of the group.
/// The collection of health descriptions.
public async Task> CheckTargetHealthForGroup(string groupName)
{
List result = null!;
try
{
var groupResponse =
await _amazonElasticLoadBalancingV2.DescribeTargetGroupsAsync(
new DescribeTargetGroupsRequest()
{
Names = new List() { groupName }
});
var healthResponse =
await _amazonElasticLoadBalancingV2.DescribeTargetHealthAsync(
new DescribeTargetHealthRequest()
{
TargetGroupArn = groupResponse.TargetGroups[0].TargetGroupArn
});
;
result = healthResponse.TargetHealthDescriptions;
}
catch (TargetGroupNotFoundException)
{
Console.WriteLine($"Target group {groupName} not found.");
}
return result;
}
```
+ For API details, see [DescribeTargetHealth](https://docs.aws.amazon.com/goto/DotNetSDKV3/elasticloadbalancingv2-2015-12-01/DescribeTargetHealth) in *AWS SDK for .NET API Reference*.
------
#### [ CLI ]
**AWS CLI**
**Example 1: To describe the health of the targets for a target group**
The following `describe-target-health` example displays health details for the targets of the specified target group. These targets are healthy.
```
aws elbv2 describe-target-health \
--target-group-arn {{arn:aws:elasticloadbalancing:us-west-2:123456789012:targetgroup/my-targets/73e2d6bc24d8a067}}
```
Output:
```
{
"TargetHealthDescriptions": [
{
"HealthCheckPort": "80",
"Target": {
"Id": "i-ceddcd4d",
"Port": 80
},
"TargetHealth": {
"State": "healthy"
}
},
{
"HealthCheckPort": "80",
"Target": {
"Id": "i-0f76fade",
"Port": 80
},
"TargetHealth": {
"State": "healthy"
}
}
]
}
```
**Example 2: To describe the health of a target**
The following `describe-target-health` example displays health details for the specified target. This target is healthy.
```
aws elbv2 describe-target-health \
--targets {{Id=i-0f76fade,Port=80}} \
--target-group-arn {{arn:aws:elasticloadbalancing:us-west-2:123456789012:targetgroup/my-targets/73e2d6bc24d8a067}}
```
Output:
```
{
"TargetHealthDescriptions": [
{
"HealthCheckPort": "80",
"Target": {
"Id": "i-0f76fade",
"Port": 80
},
"TargetHealth": {
"State": "healthy"
}
}
]
}
```
The following example output is for a target whose target group is not specified in an action for a listener. This target can't receive traffic from the load balancer.
```
{
"TargetHealthDescriptions": [
{
"HealthCheckPort": "80",
"Target": {
"Id": "i-0f76fade",
"Port": 80
},
"TargetHealth": {
"State": "unused",
"Reason": "Target.NotInUse",
"Description": "Target group is not configured to receive traffic from the load balancer"
}
}
]
}
```
The following example output is for a target whose target group was just specified in an action for a listener. The target is still being registered.
```
{
"TargetHealthDescriptions": [
{
"HealthCheckPort": "80",
"Target": {
"Id": "i-0f76fade",
"Port": 80
},
"TargetHealth": {
"State": "initial",
"Reason": "Elb.RegistrationInProgress",
"Description": "Target registration is in progress"
}
}
]
}
```
The following example output is for an unhealthy target.
```
{
"TargetHealthDescriptions": [
{
"HealthCheckPort": "80",
"Target": {
"Id": "i-0f76fade",
"Port": 80
},
"TargetHealth": {
"State": "unhealthy",
"Reason": "Target.Timeout",
"Description": "Connection to target timed out"
}
}
]
}
```
The following example output is for a target that is a Lambda function and health checks are disabled.
```
{
"TargetHealthDescriptions": [
{
"Target": {
"Id": "arn:aws:lambda:us-west-2:123456789012:function:my-function",
"AvailabilityZone": "all",
},
"TargetHealth": {
"State": "unavailable",
"Reason": "Target.HealthCheckDisabled",
"Description": "Health checks are not enabled for this target"
}
}
]
}
```
+ For API details, see [DescribeTargetHealth](https://awscli.amazonaws.com/v2/documentation/api/latest/reference/elbv2/describe-target-health.html) in *AWS CLI Command Reference*.
------
#### [ Java ]
**SDK for Java 2.x**
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/javav2/usecases/resilient_service#code-examples).
```
// Checks the health of the instances in the target group.
public List checkTargetHealth(String targetGroupName) {
DescribeTargetGroupsRequest targetGroupsRequest = DescribeTargetGroupsRequest.builder()
.names(targetGroupName)
.build();
DescribeTargetGroupsResponse tgResponse = getLoadBalancerClient().describeTargetGroups(targetGroupsRequest);
DescribeTargetHealthRequest healthRequest = DescribeTargetHealthRequest.builder()
.targetGroupArn(tgResponse.targetGroups().get(0).targetGroupArn())
.build();
DescribeTargetHealthResponse healthResponse = getLoadBalancerClient().describeTargetHealth(healthRequest);
return healthResponse.targetHealthDescriptions();
}
```
+ For API details, see [DescribeTargetHealth](https://docs.aws.amazon.com/goto/SdkForJavaV2/elasticloadbalancingv2-2015-12-01/DescribeTargetHealth) in *AWS SDK for Java 2.x API 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 { TargetHealthDescriptions } = await client.send(
new DescribeTargetHealthCommand({
TargetGroupArn: TargetGroups[0].TargetGroupArn,
}),
);
```
+ For API details, see [DescribeTargetHealth](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/elastic-load-balancing-v2/command/DescribeTargetHealthCommand) in *AWS SDK for JavaScript API Reference*.
------
#### [ PowerShell ]
**Tools for PowerShell V4**
**Example 1: This example returns the health status of the Targets present in the specified Target Group.**
```
Get-ELB2TargetHealth -TargetGroupArn 'arn:aws:elasticloadbalancing:us-east-1:123456789012:targetgroup/test-tg/a4e04b3688be1970'
```
**Output:**
```
HealthCheckPort Target TargetHealth
--------------- ------ ------------
80 Amazon.ElasticLoadBalancingV2.Model.TargetDescription Amazon.ElasticLoadBalancingV2.Model.TargetHealth
```
+ For API details, see [DescribeTargetHealth](https://docs.aws.amazon.com/powershell/v4/reference) in *AWS Tools for PowerShell Cmdlet Reference (V4)*.
**Tools for PowerShell V5**
**Example 1: This example returns the health status of the Targets present in the specified Target Group.**
```
Get-ELB2TargetHealth -TargetGroupArn 'arn:aws:elasticloadbalancing:us-east-1:123456789012:targetgroup/test-tg/a4e04b3688be1970'
```
**Output:**
```
HealthCheckPort Target TargetHealth
--------------- ------ ------------
80 Amazon.ElasticLoadBalancingV2.Model.TargetDescription Amazon.ElasticLoadBalancingV2.Model.TargetHealth
```
+ For API details, see [DescribeTargetHealth](https://docs.aws.amazon.com/powershell/v5/reference) in *AWS Tools for PowerShell Cmdlet Reference (V5)*.
------
#### [ 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/elastic-load-balancing#code-examples).
```
class ElasticLoadBalancerWrapper:
"""Encapsulates Elastic Load Balancing (ELB) actions."""
def __init__(self, elb_client: boto3.client):
"""
Initializes the LoadBalancer class with the necessary parameters.
"""
self.elb_client = elb_client
def check_target_health(self, target_group_name: str) -> List[Dict[str, Any]]:
"""
Checks the health of the instances in the target group.
:return: The health status of the target group.
"""
try:
tg_response = self.elb_client.describe_target_groups(
Names=[target_group_name]
)
health_response = self.elb_client.describe_target_health(
TargetGroupArn=tg_response["TargetGroups"][0]["TargetGroupArn"]
)
except ClientError as err:
log.error(f"Couldn't check health of {target_group_name} target(s).")
error_code = err.response["Error"]["Code"]
if error_code == "LoadBalancerNotFoundException":
log.error(
"Load balancer associated with the target group was not found. "
"Ensure the load balancer exists, is in the correct AWS region, and "
"that you have the necessary permissions to access it.",
)
elif error_code == "TargetGroupNotFoundException":
log.error(
"Target group was not found. "
"Verify the target group name, check that it exists in the correct region, "
"and ensure it has not been deleted or created in a different account.",
)
log.error(f"Full error:\n\t{err}")
else:
return health_response["TargetHealthDescriptions"]
```
+ For API details, see [DescribeTargetHealth](https://docs.aws.amazon.com/goto/boto3/elasticloadbalancingv2-2015-12-01/DescribeTargetHealth) in *AWS SDK for Python (Boto3) API Reference*.
------