Dont hate ipv6 (#55)

* Allow instance to launch w/subnet default ipv6 setting

Right now, setting this to 0 launches the instance -- and then causes
the instance to be rebuilt on the next run if the subnet defaults to
assigning ipv6 addresses.

Conditionalizing this on -1 w/null allows the current behaviour to be
preserved, while not clobbering instances on subnets w/ipv6 by default.

* Add `$self` to contributors list

* README updates

Author: rsrchboy

README.md

@@ -175,7 +175,7 @@ Available targets:
 | evaluation_periods | The number of periods over which data is compared to the specified threshold. | number | `5` | no |
 | instance_enabled | Flag to control the instance creation. Set to false if it is necessary to skip instance creation | bool | `true` | no |
 | instance_type | The type of the instance | string | `t2.micro` | no |
-| ipv6_address_count | Number of IPv6 addresses to associate with the primary network interface. Amazon EC2 chooses the IPv6 addresses from the range of your subnet | number | `0` | no |
+| ipv6_address_count | Number of IPv6 addresses to associate with the primary network interface. Amazon EC2 chooses the IPv6 addresses from the range of your subnet (-1 to use subnet default) | number | `0` | no |
 | ipv6_addresses | List of IPv6 addresses from the range of the subnet to associate with the primary network interface | list(string) | `<list>` | no |
 | metric_name | The name for the alarm's associated metric. Allowed values can be found in https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/ec2-metricscollected.html | string | `StatusCheckFailed_Instance` | no |
 | metric_namespace | The namespace for the alarm's associated metric. Allowed values can be found in https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/aws-namespaces.html | string | `AWS/EC2` | no |
@@ -369,8 +369,8 @@ Check out [our other projects][github], [follow us on twitter][twitter], [apply
 
 ### Contributors
 
-|  [![Erik Osterman][osterman_avatar]][osterman_homepage]<br/>[Erik Osterman][osterman_homepage] | [![Igor Rodionov][goruha_avatar]][goruha_homepage]<br/>[Igor Rodionov][goruha_homepage] | [![Andriy Knysh][aknysh_avatar]][aknysh_homepage]<br/>[Andriy Knysh][aknysh_homepage] | [![Sergey Vasilyev][s2504s_avatar]][s2504s_homepage]<br/>[Sergey Vasilyev][s2504s_homepage] | [![Valeriy][drama17_avatar]][drama17_homepage]<br/>[Valeriy][drama17_homepage] | [![Ivan Pinatti][ivan-pinatti_avatar]][ivan-pinatti_homepage]<br/>[Ivan Pinatti][ivan-pinatti_homepage] | [![Vladimir][SweetOps_avatar]][SweetOps_homepage]<br/>[Vladimir][SweetOps_homepage] | [![Konstantin B][comeanother_avatar]][comeanother_homepage]<br/>[Konstantin B][comeanother_homepage] | [![Maarten van der Hoef][maartenvanderhoef_avatar]][maartenvanderhoef_homepage]<br/>[Maarten van der Hoef][maartenvanderhoef_homepage] |
-|---|---|---|---|---|---|---|---|---|
+|  [![Erik Osterman][osterman_avatar]][osterman_homepage]<br/>[Erik Osterman][osterman_homepage] | [![Igor Rodionov][goruha_avatar]][goruha_homepage]<br/>[Igor Rodionov][goruha_homepage] | [![Andriy Knysh][aknysh_avatar]][aknysh_homepage]<br/>[Andriy Knysh][aknysh_homepage] | [![Sergey Vasilyev][s2504s_avatar]][s2504s_homepage]<br/>[Sergey Vasilyev][s2504s_homepage] | [![Valeriy][drama17_avatar]][drama17_homepage]<br/>[Valeriy][drama17_homepage] | [![Ivan Pinatti][ivan-pinatti_avatar]][ivan-pinatti_homepage]<br/>[Ivan Pinatti][ivan-pinatti_homepage] | [![Vladimir][SweetOps_avatar]][SweetOps_homepage]<br/>[Vladimir][SweetOps_homepage] | [![Konstantin B][comeanother_avatar]][comeanother_homepage]<br/>[Konstantin B][comeanother_homepage] | [![Maarten van der Hoef][maartenvanderhoef_avatar]][maartenvanderhoef_homepage]<br/>[Maarten van der Hoef][maartenvanderhoef_homepage] | [![Chris Weyl][rsrchboy_avatar]][rsrchboy_homepage]<br/>[Chris Weyl][rsrchboy_homepage] |
+|---|---|---|---|---|---|---|---|---|---|
 
   [osterman_homepage]: https://github.com/osterman
   [osterman_avatar]: https://img.cloudposse.com/150x150/https://github.com/osterman.png
@@ -390,6 +390,8 @@ Check out [our other projects][github], [follow us on twitter][twitter], [apply
   [comeanother_avatar]: https://img.cloudposse.com/150x150/https://github.com/comeanother.png
   [maartenvanderhoef_homepage]: https://github.com/maartenvanderhoef
   [maartenvanderhoef_avatar]: https://img.cloudposse.com/150x150/https://github.com/maartenvanderhoef.png
+  [rsrchboy_homepage]: https://github.com/rsrchboy
+  [rsrchboy_avatar]: https://img.cloudposse.com/150x150/https://github.com/rsrchboy.png
 
 [![README Footer][readme_footer_img]][readme_footer_link]
 [![Beacon][beacon]][website]

README.yaml

@@ -138,3 +138,5 @@ contributors:
     github: "comeanother"
   - name: "Maarten van der Hoef"
     github: "maartenvanderhoef"
+  - name: "Chris Weyl"
+    github: "rsrchboy"

docs/terraform.md

@@ -27,7 +27,7 @@
 | evaluation_periods | The number of periods over which data is compared to the specified threshold. | number | `5` | no |
 | instance_enabled | Flag to control the instance creation. Set to false if it is necessary to skip instance creation | bool | `true` | no |
 | instance_type | The type of the instance | string | `t2.micro` | no |
-| ipv6_address_count | Number of IPv6 addresses to associate with the primary network interface. Amazon EC2 chooses the IPv6 addresses from the range of your subnet | number | `0` | no |
+| ipv6_address_count | Number of IPv6 addresses to associate with the primary network interface. Amazon EC2 chooses the IPv6 addresses from the range of your subnet (-1 to use subnet default) | number | `0` | no |
 | ipv6_addresses | List of IPv6 addresses from the range of the subnet to associate with the primary network interface | list(string) | `<list>` | no |
 | metric_name | The name for the alarm's associated metric. Allowed values can be found in https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/ec2-metricscollected.html | string | `StatusCheckFailed_Instance` | no |
 | metric_namespace | The namespace for the alarm's associated metric. Allowed values can be found in https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/aws-namespaces.html | string | `AWS/EC2` | no |

main.tf

@@ -104,8 +104,8 @@ resource "aws_instance" "default" {
   monitoring                  = var.monitoring
   private_ip                  = var.private_ip
   source_dest_check           = var.source_dest_check
-  ipv6_address_count          = var.ipv6_address_count
-  ipv6_addresses              = var.ipv6_addresses
+  ipv6_address_count          = var.ipv6_address_count < 0 ? null : var.ipv6_address_count
+  ipv6_addresses              = length(var.ipv6_addresses) == 0 ? null : var.ipv6_addresses
 
   vpc_security_group_ids = compact(
     concat(

variables.tf

@@ -146,7 +146,7 @@ variable "source_dest_check" {
 
 variable "ipv6_address_count" {
   type        = number
-  description = "Number of IPv6 addresses to associate with the primary network interface. Amazon EC2 chooses the IPv6 addresses from the range of your subnet"
+  description = "Number of IPv6 addresses to associate with the primary network interface. Amazon EC2 chooses the IPv6 addresses from the range of your subnet (-1 to use subnet default)"
   default     = 0
 }