providers/aws: aws_instance (root) block_device forces new resource on managed infrastructure (no-BC)

[pmoust]

Relates: #877
Links: #859 (comment)

For instances already managed by terraform (terraform 0.3.7 pre #877) that have block devices defined in .tf (i.e. type set to g2, set size etc), with current upstream master the block devices are being re-computed and force new resource on plan.

example configuration:

resource "aws_instance" "pph_vpn" {
    ami                 = "${var.vpn_ami}"
    instance_type       = "${var.vpn_class}"
    availability_zone   = "${lookup(var.zones, concat("zone", count.index))}"
    subnet_id           = "${element(aws_subnet.pph.*.id, count.index)}"
    associate_public_ip_address = true
    key_name            = "vpn-dec-14" #key to be used to firstly log ing to device with username openvpnas. key is in s3

    user_data           = "${file("../cloud-init/vpn.yml")}"

    tags {
        Name = "vpn0${count.index}"
    }

    block_device {
      device_name = "/dev/sda1"
      volume_type = "standard"
      volume_size = 8
      delete_on_termination = 1
    }
    security_groups     = [ "${aws_security_group.pph_admins.id}",
                            "${aws_security_group.pph_vpn.id}",
                          ]

    count               = 1
}

What is in state currently:

                "aws_instance.pph_vpn": {
                    "type": "aws_instance",
                    "depends_on": [
                        "aws_subnet.pph",
                        "aws_security_group.pph_admins",
                        "aws_security_group.pph_vpn"
                    ],
                    "primary": {
                        "id": "i-3cf1f8d6",
                        "attributes": {
                            "ami": "ami-1a942472",
                            "associate_public_ip_address": "true",
                            "availability_zone": "us-east-1b",
                            "block_device.#": "1",
                            "block_device.2849382189.delete_on_termination": "false",
                            "block_device.2849382189.device_name": "",
                            "block_device.2849382189.encrypted": "false",
                            "block_device.2849382189.snapshot_id": "snap-5203c08f",
                            "block_device.2849382189.virtual_name": "",
                            "block_device.2849382189.volume_size": "160",
                            "block_device.2849382189.volume_type": "standard",
                            "id": "i-3cf1f8d6",
                            "instance_type": "t2.micro",
                            "key_name": "vpn-dec-14",
                            "private_dns": "ip-10-30-1-53.ec2.internal",
                            "private_ip": "10.30.1.53",
                            "public_dns": "<snipped>",
                            "public_ip": "<snipped>",
                            "security_groups.#": "2",
                            "security_groups.1610004074": "sg-d1b443b5",
                            "security_groups.70589767": "sg-d6b443b2",
                            "subnet_id": "subnet-13b90264",
                            "tags.#": "1",
                            "tags.Name": "vpn00",
                            "tenancy": "default",
                            "user_data": "d012c9fdf3cdde5f3c75743c2329e6879ad5a4cb"
                        }
                    }
                },

plan with Terraform v0.3.7-dev (3339593292d2d16922cbf6270fbbb2bfea7d6440)

-/+ aws_instance.pph_vpn
    ami:                                           "ami-1a942472" => "ami-1a942472"
    associate_public_ip_address:                   "true" => "1"
    availability_zone:                             "us-east-1b" => "us-east-1b"
    block_device.#:                                "1" => "1"
    block_device.2936417914.delete_on_termination: "" => "1" (forces new resource)
    block_device.2936417914.device_name:           "" => "/dev/sda1" (forces new resource)
    block_device.2936417914.encrypted:             "" => "<computed>" (forces new resource)
    block_device.2936417914.snapshot_id:           "" => "<computed>" (forces new resource)
    block_device.2936417914.virtual_name:          "" => "" (forces new resource)
    block_device.2936417914.volume_size:           "" => "8" (forces new resource)
    block_device.2936417914.volume_type:           "" => "standard" (forces new resource)
    instance_type:                                 "t2.micro" => "t2.micro"
    key_name:                                      "vpn-dec-14" => "vpn-dec-14"
    private_dns:                                   "ip-10-30-1-53.ec2.internal" => "<computed>"
    private_ip:                                    "10.30.1.53" => "<computed>"
    public_dns:                                    "<snipped> => "<computed>"
    public_ip:                                     "<snipped>" => "<computed>"
    security_groups.#:                             "2" => "2"
    security_groups.1610004074:                    "sg-d1b443b5" => "sg-d1b443b5"
    security_groups.70589767:                      "sg-d6b443b2" => "sg-d6b443b2"
    subnet_id:                                     "subnet-13b90264" => "subnet-13b90264"
    tags.#:                                        "1" => "1"
    tags.Name:                                     "vpn00" => "vpn00"
    tenancy:                                       "default" => "<computed>"
    user_data:                                     "d012c9fdf3cdde5f3c75743c2329e6879ad5a4cb" => "d012c9fdf3cdde5f3c75743c2329e6879ad5a4cb"

If i comment out the block_device part in the .tf the plan does not mark said instance for change.

[patricklucas]

This is mostly a dupe of #913; could you comment there?

[pmoust]

@patricklucas thanks, closing in favor of #913

[ghost]

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.

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