Configure the LoadBalancer in AWS CloudWatch Alarm - amazon-web-services

Question

I have a web application on AWS and I am trying to configure my autoscaling based on the requests.
My AppLoadBalancer resource is as below:
"AppLoadBalancer": {
"Properties": {
"LoadBalancerAttributes": [
{
"Key": "idle_timeout.timeout_seconds",
"Value": "60"
}
],
"Name": "sample-app-v1",
"Scheme": "internet-facing",
"SecurityGroups": [
"sg-1abcd234"
],
"Subnets": {
"Fn::FindInMap": [
"LoadBalancerSubnets",
{
"Ref": "AWS::Region"
},
"Subnets"
]
},
"Tags": [
{
"Key": "Name",
"Value": "sample-app-v1"
},
{
"Key": "StackName",
"Value": "sample-app"
},
{
"Key": "StackVersion",
"Value": "v1"
}
]
},
"Type": "AWS::ElasticLoadBalancingV2::LoadBalancer"
}
I am trying to configure a CloudWatch Alarm like this:
"RequestCountTooHighAlarm": {
"Properties": {
"AlarmActions": [
{
"Ref": "ScaleUp"
}
],
"AlarmDescription": "Scale-up if request count >= 8000 for last 5 minute",
"ComparisonOperator": "GreaterThanOrEqualToThreshold",
"Dimensions": [
{
"Name": "LoadBalancer",
"Value": [
{
"Fn::GetAtt": [
"AppLoadBalancer",
"LoadBalancerFullName"
]
}
]
}
],
"EvaluationPeriods": 1,
"MetricName": "RequestCount",
"Namespace": "AWS/ApplicationELB",
"OKActions": [
{
"Ref": "ScaleDown"
}
],
"Period": 300,
"Statistic": "SampleCount",
"Threshold": 8000
},
"Type": "AWS::CloudWatch::Alarm"
}
However, my stack continues to fail and I don't know what is wrong here. Here is the error which I am getting.
ERROR: RequestCountTooHighAlarm CREATE_FAILED: Value of property Value must be of type String
ERROR: sample-app-v1 CREATE_FAILED: The following resource(s) failed to create: [RequestCountTooHighAlarm].
Can somebody suggest?

Answer 1

The property mentioned requires a string. You have it defined as a list:
"Value": [
{
"Fn::GetAtt": [
"AppLoadBalancer",
"LoadBalancerFullName"
]
} ]
The [] brackets defines a list in JSON. Remove the outside brackets in the Value value, and use only the Fn::GetAt portion. That call will return a string.