Use one aws_cloudwatch_event_target for multiple aws_cloudwatch_event_rule - same like "aws events put-targets"

[youwalther65]

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Terraform CLI and Terraform AWS Provider Version

$ terraform -v Terraform v1.1.4 on linux_amd64

• provider registry.terraform.io/hashicorp/aws v4.3.0
• provider registry.terraform.io/hashicorp/cloudinit v2.2.0
• provider registry.terraform.io/hashicorp/http v2.1.0
• provider registry.terraform.io/hashicorp/local v2.1.0
• provider registry.terraform.io/hashicorp/null v3.1.0
• provider registry.terraform.io/hashicorp/random v3.1.0
• provider registry.terraform.io/hashicorp/template v2.2.0
• provider registry.terraform.io/hashicorp/tls v3.1.0

Affected Resource(s)

AWS proivder resource aws_cloudwatch_event_target resource aws_cloudwatch_event_rule

Following: https://github.com/aws/aws-node-termination-handler#4-create-amazon-eventbridge-rules

I want to create multiple EventBridge rules which use the same SQS as a target target. Using AWS CLI "aws events pu-targets" I can use the same target ID and SQS ARN fo rmultiple event rules. Using Terraform I get an error

Terraform Configuration Files

Please include all Terraform configurations required to reproduce the bug. Bug reports without a functional reproduction may be closed without investigation.

$ cat nth-eventbridge.tf
resource "aws_cloudwatch_event_rule" "karpenter_nth_SpotTermRule" {
  count = var.enable_karpenter ? 1 : 0

  name        = "${local.name}-SpotTermRule"
  description = "Capture EC2 Spot Instance Interruption Warnings"

  event_pattern = <<-EOF
  {
    "source": ["aws.ec2"],
    "detail-type": ["EC2 Spot Instance Interruption Warning"]
  }
EOF
}

resource "aws_cloudwatch_event_target" "karpenter_nth_target1" {
  count = var.enable_karpenter ? 1 : 0

  rule      = aws_cloudwatch_event_rule.karpenter_nth_SpotTermRule[0].name
  target_id = "SendToSQS1"
  arn       = aws_sqs_queue.karpenter_nth_queue[0].arn
}

resource "aws_cloudwatch_event_rule" "karpenter_nth_RebalanceRule" {
  count = var.enable_karpenter ? 1 : 0

  name        = "${local.name}-SpotTermRule"
  description = "Capture EC2 Instance Rebalance Recommendations"

  event_pattern = <<-EOF
  {
    "source": ["aws.ec2"],
    "detail-type": ["EC2 Instance Rebalance Recommendation"]
  }
EOF
}

resource "aws_cloudwatch_event_target" "karpenter_nth_target2" {
  count = var.enable_karpenter ? 1 : 0

  rule      = aws_cloudwatch_event_rule.karpenter_nth_RebalanceRule[0].name
  target_id = "SendToSQS2"
  arn       = aws_sqs_queue.karpenter_nth_queue[0].arn
}

resource "aws_cloudwatch_event_rule" "karpenter_nth_InstanceStateChangeRule" {
  count = var.enable_karpenter ? 1 : 0

  name        = "${local.name}-SpotTermRule"
  description = "Capture EC2 Instance State-change Notifications"

  event_pattern = <<-EOF
  {
    "source": ["aws.ec2"],
    "detail-type": ["EC2 Instance State-change Notification"]
  }
EOF
}

resource "aws_cloudwatch_event_target" "karpenter_nth_target3" {
  count = var.enable_karpenter ? 1 : 0

  rule      = aws_cloudwatch_event_rule.karpenter_nth_InstanceStateChangeRule[0].name
  target_id = "SendToSQS3"
  arn       = aws_sqs_queue.karpenter_nth_queue[0].arn
}

Expected Behavior

Using same target for multiple EventBridge rules

Actual Behavior

error message ╷ │ Error: error creating EventBridge Rule (git-eks-demo-ipv4-SpotTermRule): ConcurrentModificationException: com.amazon.aws.platform.tagris.client.exception.TagrisClientException: A resource with the same resourceName but a different internalId already exists: 86bbb8d2-b6a5-39d6-5813-5474a616804d │ │ with aws_cloudwatch_event_rule.karpenter_nth_RebalanceRule[0], │ on nth-eventbridge.tf line 23, in resource "aws_cloudwatch_event_rule" "karpenter_nth_RebalanceRule": │ 23: resource "aws_cloudwatch_event_rule" "karpenter_nth_RebalanceRule" { │

[justinretzolk]

Hey @youwalther65 👋 Thank you for taking the time to raise this! Based on the error logged, I suspect this is due to your having multiple aws_cloudwatch_event_rule resources that have the same value for the name argument. Can you try setting the name argument to a unique value and test to verify that resolves the issue?

[youwalther65]

Hey @justinretzolk thank you very much, appreciate your fast response AND resolution. Sorry for that - never codify in a call and have someone look at your code if you are not sure ;-) Issue solved, worked great , thx again

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