WIP: Expose AMI's root volume size

[tomelliff]

Attempting to implement #1623

The idea is that an instance module should be able to default the root volume to the size of the AMI's root volume. Right now I have a couple of AMIs that have a considerably larger root volume (CUDA/NVidia drivers take a lot of space) and I'd ideally not have to remember to override the root volume size before an apply time failure due to the root volume size being defaulted to a smaller size than the AMI root volume size.

Right now the tests I've added are failing with the root_volume_size not being set at all.
I'll debug this when I get a chance but just want to push the work up for now.

The work here carries on from #1572

[tomelliff]

Hmmm... not sure why the Travis build didn't fail last night. Those tests fail locally for me when I run them and building the provider and applying the following config doesn't output the root_volume_size into the state:

data "aws_ami" "selected" {
  most_recent = true

  filter {
    name   = "virtualization-type"
    values = ["hvm"]
  }

  filter {
    name   = "name"
    values = ["amzn-ami-vpc-nat*"]
  }

  owners = ["amazon"]
}

$ terraform state show aws_ami.selected
id                                                         = ami-38d20741
architecture                                               = x86_64
block_device_mappings.#                                    = 1
block_device_mappings.3607311014.device_name               = /dev/xvda
block_device_mappings.3607311014.ebs.%                     = 6
block_device_mappings.3607311014.ebs.delete_on_termination = true
block_device_mappings.3607311014.ebs.encrypted             = false
block_device_mappings.3607311014.ebs.iops                  = 0
block_device_mappings.3607311014.ebs.snapshot_id           = snap-0a9d1c80ae7d1f0ad
block_device_mappings.3607311014.ebs.volume_size           = 8
block_device_mappings.3607311014.ebs.volume_type           = standard
block_device_mappings.3607311014.no_device                 = 
block_device_mappings.3607311014.virtual_name              = 
creation_date                                              = 2017-10-01T09:12:53.000Z
description                                                = Amazon Linux AMI 2017.09.0.20170930 x86_64 VPC NAT HVM EBS
filter.#                                                   = 2
filter.3298344342.name                                     = name
filter.3298344342.values.#                                 = 1
filter.3298344342.values.0                                 = amzn-ami-vpc-nat*
filter.490168357.name                                      = virtualization-type
filter.490168357.values.#                                  = 1
filter.490168357.values.0                                  = hvm
hypervisor                                                 = xen
image_id                                                   = ami-38d20741
image_location                                             = amazon/amzn-ami-vpc-nat-hvm-2017.09.0.20170930-x86_64-ebs
image_owner_alias                                          = amazon
image_type                                                 = machine
most_recent                                                = true
name                                                       = amzn-ami-vpc-nat-hvm-2017.09.0.20170930-x86_64-ebs
owner_id                                                   = 137112412989
owners.#                                                   = 1
owners.0                                                   = amazon
product_codes.#                                            = 0
public                                                     = true
root_device_name                                           = /dev/xvda
root_device_type                                           = ebs
root_snapshot_id                                           = snap-0a9d1c80ae7d1f0ad
sriov_net_support                                          = simple
state                                                      = available
state_reason.%                                             = 2
state_reason.code                                          = UNSET
state_reason.message                                       = UNSET
tags.%                                                     = 0
virtualization_type                                        = hvm

Adding some debug logging to the data source shows it triggering the if condition at https://github.com/terraform-providers/terraform-provider-aws/pull/2114/files#diff-6c1ccb9926bf208fafaed38fa038b2b4R385 so not sure what I'm missing there.

I've got a fair bit on for a couple of days so will probably take a look at it again on Friday/the weekend but I'm confused in both why it's failing locally but also why Travis is passing.

[bflad]

@tomelliff is this still WIP?

[clangaxon]

Any update on this? It would be quite handy ...

[tomelliff]

I'd completely forgotten about this to be honest.

I can take another look at it if it's useful for others still.

[bflad]

Closing due to WIP and lack of activity. If you feel like picking it back up, we can certainly reopen this 👍

[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.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. Thanks!