Adding more instances is messing up my volume attachments

Terraform
14

Hi @apparentlymart

Could you please help on this. Below I have elaborated what I’m trying to acheive.

How to have both “aws_ebs_volume” “size” and “aws_volume_attachment” “device_name” in the same map of “node_disks” so that I can call it in the resource.

Example:

I could have a list of data_disks as well it’s corresponding disk_size as variable input as shown below.

variable "dnodes" {
  default = ["1", "2", "3"]
}

variable "data_disks" {
  description = "device list for EC2 mapping"
  default     = ["/dev/xvdb", "/dev/xvdc" ]
}

variable "disk_size" {
  description = "device list for EC2 mapping"
  default     = ["10", "30"]
}

I want to be able to have something like this.

node_disks = {
  "1:/dev/xvdb" = {
    "disk_dev_path" = "/dev/xvdb"
    "node_name" = "1"
    "disk_size" = "10"
  }
  "1:/dev/xvdc" = {
    "disk_dev_path" = "/dev/xvdc"
    "node_name" = "1"
    "disk_size" = "30"
  }
  "2:/dev/xvdb" = {
    "disk_dev_path" = "/dev/xvdb"
    "node_name" = "2"
    "disk_size" = "10"
  }
  "2:/dev/xvdc" = {
    "disk_dev_path" = "/dev/xvdc"
    "node_name" = "2"
    "disk_size" = "30"
  }
  "3:/dev/xvdb" = {
    "disk_dev_path" = "/dev/xvdb"
    "node_name" = "3"
    "disk_size" = "10"
  }
  "3:/dev/xvdc" = {
    "disk_dev_path" = "/dev/xvdc"
    "node_name" = "3"
    "disk_size" = "30"
  }
}

I want to be able to use it here as shown below:

resource "aws_ebs_volume" "ebs_volume" {
  for_each = local.node_disks
    availability_zone = "us-west-1a"
    size              =  each.value.disk_size

I tried to build another map for size as shown below,

locals {
ebs_size = { for pair in setproduct(local.dnodes, var.disk_size) : "${pair[0]}:${pair[1]}" => {
    node_name  = pair[0]
    data_dev_size = pair[1]
  } }
}

However when I run plan, it throws below error.

resource "aws_ebs_volume" "data_disk" {
  for_each          = local.ebs_size
  availability_zone = "us-west-1a"
  size              = each.value.data_dev_size
  type              = "gp2"
}

resource "aws_volume_attachment" "dnode_data_disk" {
  for_each = local.node_disks

  device_name  = each.value.disk_dev_path
  instance_id  = aws_instance.this[each.value.node_name].id
  volume_id    = aws_ebs_volume.data_disk[each.key].id
  force_detach = true
}

Error: Invalid index

  on ../../main.tf line 87, in resource "aws_volume_attachment" "dnode_data_disk":
  87:   volume_id    = aws_ebs_volume.data_disk[each.key].id
    |----------------
    | aws_ebs_volume.data_disk is object with 4 attributes
    | each.key is "1:/dev/xvdb"