documentation example for aws_cloudwatch_composite_alarm is incorrect

[paravz]

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Terraform CLI and Terraform AWS Provider Version

$  terraform -v
Terraform v0.15.4
on linux_amd64
+ provider registry.terraform.io/hashicorp/aws v3.42.0

Affected Resource(s)

• aws_cloudwatch_composite_alarm

Terraform Configuration Files

locals {
  alarm_rule_with_newlines = <<-EOF
    ALARM(${aws_cloudwatch_metric_alarm.alarm-test1.alarm_name}) OR
    ALARM(${aws_cloudwatch_metric_alarm.alarm-test2.alarm_name})
  EOF
}

resource "aws_cloudwatch_metric_alarm" "alarm-test1" {
  alarm_name          = "alarm-test1"
  comparison_operator = "GreaterThanThreshold"
  evaluation_periods  = "1"
  metric_name         = "ApproximateNumberOfMessagesVisible"
  namespace           = "AWS/SQS"
  period              = "300"
  statistic           = "Sum"
  threshold           = "0.0"
  treat_missing_data  = "ignore"
  alarm_description   = "Queue backlog exceeded"
  dimensions = {
    QueueName = "dummy-queue"
  }
}

resource "aws_cloudwatch_metric_alarm" "alarm-test2" {
  alarm_name          = "alarm-test2"
  comparison_operator = "GreaterThanThreshold"
  evaluation_periods  = "1"
  metric_name         = "ApproximateNumberOfMessagesVisible"
  namespace           = "AWS/SQS"
  period              = "300"
  statistic           = "Sum"
  threshold           = "0.0"
  treat_missing_data  = "ignore"
  alarm_description   = "Queue backlog exceeded"
  dimensions = {
    QueueName = "dummy-queue"
  }
}

resource "aws_cloudwatch_composite_alarm" "composite-alarm-test" {
  alarm_description = "Test/Dummy composite alarm"
  alarm_name        = "test-composite-alarm"

  # fails
  alarm_rule = <<EOF
ALARM(${aws_cloudwatch_metric_alarm.alarm-test1.alarm_name}) OR
ALARM(${aws_cloudwatch_metric_alarm.alarm-test2.alarm_name})
EOF

  # works
  #alarm_rule = trimspace(replace(local.alarm_rule_with_newlines, "/\n+/", " ")) 
}

Debug Output

$  terraform apply

Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  # aws_cloudwatch_composite_alarm.composite-alarm-test will be created
  + resource "aws_cloudwatch_composite_alarm" "composite-alarm-test" {
      + actions_enabled   = true
      + alarm_description = "Test/Dummy composite alarm"
      + alarm_name        = "test-composite-alarm"
      + alarm_rule        = <<-EOT
            ALARM(alarm-test1) OR
            ALARM(alarm-test2)
        EOT
      + arn               = (known after apply)
      + id                = (known after apply)
      + tags_all          = (known after apply)
    }

  # aws_cloudwatch_metric_alarm.alarm-test1 will be created
  + resource "aws_cloudwatch_metric_alarm" "alarm-test1" {
      + actions_enabled                       = true
      + alarm_description                     = "Queue backlog exceeded"
      + alarm_name                            = "alarm-test1"
      + arn                                   = (known after apply)
      + comparison_operator                   = "GreaterThanThreshold"
      + dimensions                            = {
          + "QueueName" = "dummy-queue"
        }
      + evaluate_low_sample_count_percentiles = (known after apply)
      + evaluation_periods                    = 1
      + id                                    = (known after apply)
      + metric_name                           = "ApproximateNumberOfMessagesVisible"
      + namespace                             = "AWS/SQS"
      + period                                = 300
      + statistic                             = "Sum"
      + tags_all                              = (known after apply)
      + threshold                             = 0
      + treat_missing_data                    = "ignore"
    }

  # aws_cloudwatch_metric_alarm.alarm-test2 will be created
  + resource "aws_cloudwatch_metric_alarm" "alarm-test2" {
      + actions_enabled                       = true
      + alarm_description                     = "Queue backlog exceeded"
      + alarm_name                            = "alarm-test2"
      + arn                                   = (known after apply)
      + comparison_operator                   = "GreaterThanThreshold"
      + dimensions                            = {
          + "QueueName" = "dummy-queue"
        }
      + evaluate_low_sample_count_percentiles = (known after apply)
      + evaluation_periods                    = 1
      + id                                    = (known after apply)
      + metric_name                           = "ApproximateNumberOfMessagesVisible"
      + namespace                             = "AWS/SQS"
      + period                                = 300
      + statistic                             = "Sum"
      + tags_all                              = (known after apply)
      + threshold                             = 0
      + treat_missing_data                    = "ignore"
    }

Plan: 3 to add, 0 to change, 0 to destroy.

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

aws_cloudwatch_metric_alarm.alarm-test1: Creating...
aws_cloudwatch_metric_alarm.alarm-test2: Creating...
aws_cloudwatch_metric_alarm.alarm-test2: Creation complete after 1s [id=alarm-test2]
aws_cloudwatch_metric_alarm.alarm-test1: Creation complete after 1s [id=alarm-test1]
aws_cloudwatch_composite_alarm.composite-alarm-test: Creating...
╷
│ Error: error creating CloudWatch Composite Alarm (test-composite-alarm): ValidationError: AlarmRule must not contain leading or trailing whitespace or be null
│       status code: 400, request id: a93cd490-ae43-40b4-a940-1dfea2b4a284
│
│   with aws_cloudwatch_composite_alarm.composite-alarm-test,
│   on composite-alarm.tf line 34, in resource "aws_cloudwatch_composite_alarm" "composite-alarm-test":
│   34: resource "aws_cloudwatch_composite_alarm" "composite-alarm-test" {
│

Expected Behavior

Composite Alarm is created as per documentation example https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/cloudwatch_composite_alarm#example-usage

Actual Behavior

Error from AWS on apply, likely because of newlines in heredoc:
ValidationError: AlarmRule must not contain leading or trailing whitespace or be null

Steps to Reproduce

1. terraform apply

[jay-dizzale]

Hi there, the issue still persists. EOF<< will add additional whitspaces, which then trigger the error

Error: error creating CloudWatch Composite Alarm (test-composite-alarm): ValidationError: AlarmRule must not contain leading or trailing whitespace or be null

I had to add the alarmnames to a list and joint with 'or':
alarm_rule = join(" OR ", tolist(["test-alarm", "test-alarm-2"])

I think the provider should remove the whitespaces.