如何在CloudFormation中从弹性豆茎环境中提取负载均衡器名称

Question

我已经用以下代码片段在CloudFormation中创建了一个弹性Beanstalk和CloudWatch警报：

        "ElasticBeanstalkEnvironment": {
        "Type": "AWS::ElasticBeanstalk::Environment",
        "Properties": {
            "ApplicationName": "my-app",
            "EnvironmentName": "my-eb",
            "SolutionStackName": "64bit Amazon Linux 2018.03 v3.0.1 running Tomcat 8 Java 8",
            "OptionSettings": [
                {
                    "Namespace": "aws:elb:loadbalancer",
                    "OptionName": "CrossZone",
                    "Value": "true"
                },
                {
                    "Namespace": "aws:elb:listener:80",
                    "OptionName": "ListenerProtocol",
                    "Value": "HTTP"
                },
                {
                    "Namespace": "aws:elb:listener:80",
                    "OptionName": "InstancePort",
                    "Value": "80"
                },
                etc...
            ]
        },
        "CloudWatchBacken500XXAlarm": {
            "Type": "AWS::CloudWatch::Alarm",
            "Properties" : {
                "AlarmActions": ["arn:aws:sns:us-east-1:12345678:mysnstopic"],
                "Namespace": "AWS/ELB",
                "Dimensions": [{
                    "Name": "LoadBalancerName",
                    "Value" : {
                        "Fn::GetAtt": [
                            "ElasticBeanstalkEnvironment",
                            "EndpointURL"  
                        ]
                    }
                  }],
                "MetricName": "HTTPCode_Backend_5XX",
                "Statistic": "Sum",
                "Period": "60",
                "EvaluationPeriods": "1",
                "ComparisonOperator": "GreaterThanOrEqualToThreshold",
                "Threshold": "1"
                }
        }

您可以看到，如果Elastic Beanstalk的负载均衡器接收到5XX错误，则CloudWatch警报被配置为发出警报。然而，我不能获得负载均衡器名称属性，它看起来像这样：

awseb-e-a-AWSEBLoa-AY8LC6V30OAW

相反，Fn::GetAtt("EndpointURL")属性返回负载均衡器的DNSName，如下所示：

awseb-e-a-AWSEBLoa-AY8LC6V30OAW-175133046.us-east-1.elb.amazonaws.com

它将无法正确创建CloudWatch告警，因为它希望获得负载均衡器名称，而不是DNSName。

获取负载均衡器名称的最佳方式是什么？我不想创建负载均衡器作为外部资源，比如"AWS::ElasticLoadBalancing::LoadBalancer“，或者尝试使用某个子串方法从DNSName字符串中提取名称字符串。

Answer 1

好的，我找到了一个解决方案，我已经能够通过对从- Fn::GetAtt("EndpointURL")返回的DNSName字符串进行几次Split/Select/Join调用，从端点提取LoadBalancerName。代码如下：

"CloudWatchBackend500XXAlarm": {
"Type": "AWS::CloudWatch::Alarm",
"Properties" : {
    "AlarmDescription": "Elastic Beanstalk Has Received 5XX Backend Connection Errors",
    "AlarmActions": ["arn:aws:sns:us-east-1:1234567890:mysnstopic"],
    "Namespace": "AWS/ELB",
    "Dimensions": [
        {
            "Name": "LoadBalancerName",
            "Value": {
                "Fn::Join": ["", [{
                    "Fn::Select": [
                        "0",
                        {
                            "Fn::Split": ["AWSEBLoa-",
                                {
                                    "Fn::GetAtt": [
                                        "ElasticBeanstalkEnvironment",
                                        "EndpointURL"
                                    ]
                                }
                            ]
                        }
                    ]
                },
                "AWSEBLoa-",
                {
                    "Fn::Select": [
                        "0",
                        {
                            "Fn::Split": ["-",
                                {
                                    "Fn::Select": [
                                        "1",
                                        {
                                            "Fn::Split": ["AWSEBLoa-",
                                                {
                                                    "Fn::GetAtt": [
                                                        "ElasticBeanstalkEnvironment",
                                                        "EndpointURL"
                                                    ]
                                                }
                                            ]
                                        }
                                    ]
                                }
                            ]
                        }
                    ]
                }
            ]]
        }
        }
    ],                  
    "MetricName": "HTTPCode_Backend_5XX",
    "Statistic": "Sum",
    "Period": "60",
    "EvaluationPeriods": "1",
    "ComparisonOperator": "GreaterThanOrEqualToThreshold",
    "Threshold": "1"
}

}

即上面的代码能够从'awseb-k-3-AWSEBLoa-11B26NY4PQB9A-739614614.us-east-1.elb.amazonaws.com‘中提取“awseb-K-3-AWSEBLoa-11B26NY4PQB9A”，并且CloudWatch警报工作正常。我认为我必须调整代码以使用内部负载均衡器，即在DNSName的开头使用' internal -‘格式化，但我现在很好。

我已经向亚马逊网络服务提交了一个请求，要求他们添加一个CloudFormation方法来返回LoadBalancer名称，而不仅仅是DNSName。

Answer 2

使用ebextensions创建警报要容易得多-因为获取ELB名称与取值一样简单：{ "Ref“："AWSEBLoadBalancer”}

创建一个扩展名为.config (比如- BackendErrors.config)的文件，并将其放在名为".ebextensions“的文件夹中。完整的ebextension如下所示：

Resources:
  CloudWatchBacken500XXAlarm:
    Type: AWS::CloudWatch::Alarm
    Properties:
      AlarmDescription: "Elastic Beanstalk Has Received 5XX Backend Connection Errors"
      AlarmName: { "Fn::Join" : ["", [{ "Ref" : "AWSEBEnvironmentName" }, "-Backend-5XX-Alarm." ]]}
      AlarmActions:
        - "arn:aws:sns:us-east-1:123456789012:mysnstopic"
      Namespace: AWS/ELB
      Dimensions:
        - Name: LoadBalancerName
          Value: { "Ref" : "AWSEBLoadBalancer" }
      MetricName: HTTPCode_Backend_5XX
      Statistic: Sum
      Period: 60
      EvaluationPeriods: 1
      Threshold: 1
      ComparisonOperator: GreaterThanOrEqualToThreshold

应该在应用程序源代码捆绑包的顶层创建.ebextensions文件夹：

~/workspace/my-application/
|-- .ebextensions
|   |-- BackendErrors.config

Answer 3

如果您有访问环境名称的权限，则可以执行DescribeEnvironmentResources接口调用。响应将包括有关您的环境的负载均衡器的信息。