[Bug]: aws_instance fails with subnet and launch template having security group

[dhrkumar]

Terraform Core Version

1.3.6

AWS Provider Version

5.8.0

Affected Resource(s)

aws_instance

Expected Behavior

One should be able to launch an EC2 instance with a launch template(having security group) in a subnet without configuring network interface block.

Actual Behavior

Terraform failed to create an EC2 instance with an AWS message that network interfaces and an instance-level security groups may not be specified together.

Relevant Error/Panic Output Snippet

│ Error: creating EC2 Instance: InvalidParameterCombination: Network interfaces and an instance-level security groups may not be specified on the same request
│ 	status code: 400

Terraform Configuration Files

variable "aws_region" {}
variable "aws_access_key_id" {}
variable "aws_secret_key_id" {}
variable "aws_session_token" {}

provider "aws" {
  access_key = var.aws_access_key_id
  secret_key = var.aws_secret_key_id
  token      = var.aws_session_token
  region     = var.aws_region
}

locals {
  tags = { "created-by" : "dhrkumar" }
}
resource "aws_iam_role" "role" {
  assume_role_policy = jsonencode({
    Version   = "2012-10-17"
    Statement = [
      {
        Action    = "sts:AssumeRole"
        Effect    = "Allow"
        Principal = {
          Service = "ec2.amazonaws.com"
        }
      },
    ]
  })
  name = "launch-template-ec2-role"
  path = "/ec2/instance/"
  tags = local.tags
}
resource "aws_iam_instance_profile" "instance_profile" {
  name = "ec2-instance-profile"
  path = "/ec2/instance/"
  role = aws_iam_role.role.name
}
data "aws_subnet" "subnet" {
  filter {
    name   = "tag:Name"
    values = ["DEMO Private Subnet (AZ2)"]
  }
}
resource "aws_security_group" "sg" {
  description = "SG for EC2"
  name        = "ec2-security-group"
  tags        = local.tags
  vpc_id      = data.aws_subnet.subnet.vpc_id
}
resource "aws_launch_template" "lt" {
  description             = "Launch template for ec2"
  disable_api_termination = false
  image_id                = "ami-06ca3ca175f37dd66"
  instance_type           = "t3.nano"
  name                    = "ec2-linux"
  tags                    = local.tags
  update_default_version  = true
  vpc_security_group_ids  = [aws_security_group.sg.id]
  iam_instance_profile {
    arn = aws_iam_instance_profile.instance_profile.arn
  }
  metadata_options {
    http_endpoint               = "enabled"
    http_put_response_hop_limit = 2
    http_tokens                 = "required"
  }
  monitoring {
    enabled = true
  }
  tag_specifications {
    resource_type = "instance"
    tags          = local.tags
  }
  tag_specifications {
    resource_type = "volume"
    tags          = local.tags
  }
}
resource "aws_instance" "ec2" {
  subnet_id = data.aws_subnet.subnet.id
  tags      = local.tags
  launch_template {
    name    = aws_launch_template.lt.name
    version = "$Latest"
  }
  root_block_device {
    delete_on_termination = true
  }
}

Steps to Reproduce

Replace name in aws_subnet data source and apply above configuration code to get error.

Debug Output

No response

Panic Output

No response

Important Factoids

No response

References

No response

Would you like to implement a fix?

Yes

[github-actions]

Community Note

Voting for Prioritization

• Please vote on this issue by adding a 👍 reaction to the original post to help the community and maintainers prioritize this request.
• Please see our prioritization guide for information on how we prioritize.
• Please do not leave "+1" or other comments that do not add relevant new information or questions, they generate extra noise for issue followers and do not help prioritize the request.

Volunteering to Work on This Issue

• If you are interested in working on this issue, please leave a comment.
• If this would be your first contribution, please review the contribution guide.

[github-actions]

This functionality has been released in v5.12.0 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[github-actions]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.
If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.