ebs_block_device always shows changes on an ec2 instance that has more than 1 volume attached

[leonardocaylent]

Description

Everytime that a change is performed to an ec2 instance with more than 1 ebs volume attached, the terraform plan shows changes for all the ebs_block_devices as the following:

Objects have changed outside of Terraform
ebs_block_device {
-           delete_on_termination = false -> null
-           device_name           = "/dev/sdb" -> null
-           encrypted             = true -> null
-           iops                  = 16000 -> null
....(continues)....
       ebs_block_device {
-           delete_on_termination = false -> null
-           device_name           = "/dev/sdd" -> null
-           encrypted             = true -> null
-           iops                  = 16000 -> null
....(continues)....
ebs_block_device {
+           delete_on_termination = false
+           device_name           = "/dev/sdb"
+           encrypted             = true
....(continues)....
+       ebs_block_device {
+           delete_on_termination = false
+           device_name           = "/dev/sdd"
+           encrypted             = true

This could become in a large terraform plan just with 6 ec2 instances with 6 volumes each which becomes a little harder to read and generates confusion because this is not being managed by the module as:

# ebs_block_device managed by separate resource

Since we are not using this feature, shall we include to both resources "aws_instance"."ignore_ami" and also resource "aws_instance"."this" the following ignore?

lifecycle {
    ignore_changes = [
      ebs_block_device,
    ]

If there is anything better or what I'm proposing has a huge impact and a lot of drawbacks please let me know. Happy to help on solving this issue that probably is affecting multiple persons

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• ✋ I have searched the open/closed issues and my issue is not listed.

⚠️ Note

Versions

• Module version [Required]: This happens in the major 6 (all minors included)

• Terraform version:
  1.11

• Provider version(s):
  aws version 6

Reproduction Code [Required]

Create a ec2 instance with 6 EBS volumes, after the first terraform apply try to change the iops on all the volumes. That will trigger the plan with the additional "Objects have changed outside of Terraform"

module "ec2_test" {
  source = "git::https://github.com/terraform-aws-modules/terraform-aws-ec2-instance.git?ref=c90bc6edc889c73bdd1e07f01b656d93902cf364"

  name = "test"

  # Instance Configuration
  ami                         = "ami-x"
  instance_type               = "m7i.large"
  availability_zone           = "us-east-1a"
  subnet_id                   = "subnet-x"
  vpc_security_group_ids      = ["sg-x"]
  associate_public_ip_address = false


  disable_api_termination = true
  create_security_group   = false


  enable_volume_tags = false




  metadata_options = {
    http_endpoint               = "enabled"
    http_tokens                 = "optional"
    http_put_response_hop_limit = 1
  }


  root_block_device = {
    delete_on_termination = false
    type                  = "gp3"
    size                  = 75
    iops                  = 16000
    throughput            = 1250
    
  }

  # Additional EBS Volumes
  ebs_volumes = {
    "/dev/sdd" = {
      type                 = "gp3"
      size                 = 100
      multi_attach_enabled = false
      iops                 = 16000
      throughput           = 1250
    }
    "/dev/sdc" = {
      type                 = "gp3"
      size                 = 100
      multi_attach_enabled = false
      iops                 = 16000
      throughput           = 1250
    }
    "/dev/sde" = {
      type                 = "gp3"
      size                 = 100
      multi_attach_enabled = false
      iops                 = 16000
      throughput           = 1250
    }
    "/dev/sdb" = {
      type                 = "gp3"
      size                 = 100
      multi_attach_enabled = false
      iops                 = 16000
      throughput           = 1250
    }
  }

  # User Data
  user_data = null

  # Tags
  tags = {
    "test" = "yes"
  }

  # Lifecycle Configuration
  user_data_replace_on_change = false
  ignore_ami_changes          = true
}

Expected behavior

Any change for all the ebs_block_device that the ec2 instance has attached should not appear in the terraform plan as "Objects have changed outside of Terraform"

Actual behavior

Drift is showing up even when there were no manual changes applied to the ec2 instance

[github-actions]

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[leonardocaylent]

This is still an issue. Testing if the fix proposed can be applied or it's a more complex issue