如何使用 terraform 向 Elastic Beanstalk 环境创建的负载均衡器添加警报？

Question

我想添加一个警报，当 Elastic Beanstalk 环境创建的应用程序负载均衡器中有太多 5xx 错误时触发。

EB 环境由 terraform 脚本创建。 terraform创建资源aws_elastic_beanstalk_environment后才能知道负载均衡器的名称。

This page 表示elastic-beanstalk-environment 有一个名为elb_load_balancers 的输出。我想我可能可以使用这个输出来创建一个aws_cloudwatch_metric_alarm 资源。

以下 terraform 脚本是我现在所做的。它不工作

resource "aws_cloudwatch_metric_alarm" "alarm_5xx" {
  alarm_name          = "EB 5XX Alarm"
  comparison_operator = "GreaterThanOrEqualToThreshold"
  evaluation_periods  = "1"
  metric_name         = "HTTPCode_ELB_5XX_Count"
  namespace           = "AWS/ApplicationELB"
  period              = "60"
  statistic           = "Sum"
  threshold           = "10"

  dimensions = {
    # How can I put the name of the dynamically generated load balancer here?
    LoadBalancer = "${aws_elastic_beanstalk_environment.my_eb_environment_name.elb_load_balancers}" # This line doesn't work
  }

  alarm_description = "This metric monitors number of 5xx erros in the application load balancer"
}

上面的脚本在我运行terraform apply -target=aws_cloudwatch_metric_alarm.alarm_5xx时产生如下错误：

* aws_cloudwatch_metric_alarm.alarm_5xx: Resource 'aws_elastic_beanstalk_environment.my_eb_environment_name' does not have attribute 'elb_load_balancers' for variable 'aws_elastic_beanstalk_environment.my_eb_environment_name.elb_load_balancers'

我也试过了

resource "aws_cloudwatch_metric_alarm" "alarm_5xx" {
  alarm_name          = "EB 5XX Alarm"
  comparison_operator = "GreaterThanOrEqualToThreshold"
  evaluation_periods  = "1"
  metric_name         = "HTTPCode_ELB_5XX_Count"
  namespace           = "AWS/ApplicationELB"
  period              = "60"
  statistic           = "Sum"
  threshold           = "10"

  dimensions = {
    LoadBalancer = "${aws_elastic_beanstalk_environment.RightestCARE-Api-Prod-Terraform.load_balancers}" # This line doesn't work
  }

  alarm_description = "This metric monitors number of 5xx erros in the application load balancer"
}

但这会产生以下错误：

* aws_cloudwatch_metric_alarm.alarm_5xx: dimensions (LoadBalancerName): '' expected type 'string', got unconvertible type '[]interface {}'

Answer 1

感谢ydaetskcoR 的评论。我发现以下脚本有效。

resource "aws_cloudwatch_metric_alarm" "alarm_5xx" {
  alarm_name          = "EB 5XX Alarm"
  comparison_operator = "GreaterThanOrEqualToThreshold"
  evaluation_periods  = "1"
  metric_name         = "HTTPCode_ELB_5XX_Count"
  namespace           = "AWS/ApplicationELB"
  period              = "60"
  statistic           = "Sum"
  threshold           = "10"

  dimensions = {
    LoadBalancer = "${aws_elastic_beanstalk_environment.my_eb_environment_name.load_balancers[0]}" 
  }

  alarm_description = "This metric monitors number of 5xx erros in the application load balancer"
}

Terraform 的 aws_elastic_beanstalk_environment 说它有一个导出的 load_balancers 属性。

因为我在 EB 环境中只有 1 个负载均衡器，所以我可以使用 load_balancers[0] 来获取唯一的负载均衡器。