Add capacity_type to support node group spot pricing (cloudposse#45)

## what
* Adds in support for capacity_type settings on node group 
* Removes clrf from document https://www.atechtown.com/remove-ctrl-m-character/
* Adds gitattributes so linux line endings are maintained

## why
* Who doesn't like spot pricing 
* I don't like paying full price for machines

## references
* https://aws.amazon.com/blogs/containers/amazon-eks-now-supports-provisioning-and-managing-ec2-spot-instances-in-managed-node-groups/
* https://aws.amazon.com/about-aws/whats-new/2020/12/amazon-eks-support-ec2-spot-instances-managed-node-groups/
* https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/eks_node_group#capacity_type

Co-authored-by: actions-bot <58130806+actions-bot@users.noreply.github.com>

.gitattributes

@@ -0,0 +1 @@
+* text eol=lf

README.md

@@ -1,4 +1,6 @@
+<!-- markdownlint-disable -->
 # terraform-aws-eks-node-group [![Latest Release](https://img.shields.io/github/release/cloudposse/terraform-aws-eks-node-group.svg)](https://github.com/cloudposse/terraform-aws-eks-node-group/releases/latest) [![Slack Community](https://slack.cloudposse.com/badge.svg)](https://slack.cloudposse.com)
+<!-- markdownlint-restore -->
 
 [![README Header][readme_header_img]][readme_header_link]
 
@@ -202,6 +204,7 @@ Available targets:
 | attributes | Additional attributes (e.g. `1`) | `list(string)` | `[]` | no |
 | before\_cluster\_joining\_userdata | Additional `bash` commands to execute on each worker node before joining the EKS cluster (before executing the `bootstrap.sh` script). For more info, see https://kubedex.com/90-days-of-aws-eks-in-production | `string` | `""` | no |
 | bootstrap\_additional\_options | Additional options to bootstrap.sh. DO NOT include `--kubelet-additional-args`, use `kubelet_additional_args` var instead. | `string` | `""` | no |
+| capacity\_type | Type of capacity associated with the EKS Node Group. Valid values: ON\_DEMAND, SPOT. <br>Terraform will only perform drift detection if a configuration value is provided. | `string` | `"ON_DEMAND"` | no |
 | cluster\_autoscaler\_enabled | Set true to label the node group so that the [Kubernetes Cluster Autoscaler](https://github.com/kubernetes/autoscaler/blob/master/cluster-autoscaler/cloudprovider/aws/README.md#auto-discovery-setup) will discover and autoscale it | `bool` | `null` | no |
 | cluster\_name | The name of the EKS cluster | `string` | n/a | yes |
 | context | Single object for setting entire context at once.<br>See description of individual variables for details.<br>Leave string and numeric variables as `null` to use default value.<br>Individual variable settings (non-null) override settings in context object,<br>except for attributes, tags, and additional\_tag\_map, which are merged. | <pre>object({<br>    enabled             = bool<br>    namespace           = string<br>    environment         = string<br>    stage               = string<br>    name                = string<br>    delimiter           = string<br>    attributes          = list(string)<br>    tags                = map(string)<br>    additional_tag_map  = map(string)<br>    regex_replace_chars = string<br>    label_order         = list(string)<br>    id_length_limit     = number<br>  })</pre> | <pre>{<br>  "additional_tag_map": {},<br>  "attributes": [],<br>  "delimiter": null,<br>  "enabled": true,<br>  "environment": null,<br>  "id_length_limit": null,<br>  "label_order": [],<br>  "name": null,<br>  "namespace": null,<br>  "regex_replace_chars": null,<br>  "stage": null,<br>  "tags": {}<br>}</pre> | no |
@@ -409,8 +412,10 @@ Check out [our other projects][github], [follow us on twitter][twitter], [apply
 
 ### Contributors
 
+<!-- markdownlint-disable -->
 |  [![Erik Osterman][osterman_avatar]][osterman_homepage]<br/>[Erik Osterman][osterman_homepage] | [![Andriy Knysh][aknysh_avatar]][aknysh_homepage]<br/>[Andriy Knysh][aknysh_homepage] | [![Igor Rodionov][goruha_avatar]][goruha_homepage]<br/>[Igor Rodionov][goruha_homepage] |
 |---|---|---|
+<!-- markdownlint-restore -->
 
   [osterman_homepage]: https://github.com/osterman
   [osterman_avatar]: https://img.cloudposse.com/150x150/https://github.com/osterman.png

docs/terraform.md

@@ -28,6 +28,7 @@
 | attributes | Additional attributes (e.g. `1`) | `list(string)` | `[]` | no |
 | before\_cluster\_joining\_userdata | Additional `bash` commands to execute on each worker node before joining the EKS cluster (before executing the `bootstrap.sh` script). For more info, see https://kubedex.com/90-days-of-aws-eks-in-production | `string` | `""` | no |
 | bootstrap\_additional\_options | Additional options to bootstrap.sh. DO NOT include `--kubelet-additional-args`, use `kubelet_additional_args` var instead. | `string` | `""` | no |
+| capacity\_type | Type of capacity associated with the EKS Node Group. Valid values: ON\_DEMAND, SPOT. <br>Terraform will only perform drift detection if a configuration value is provided. | `string` | `"ON_DEMAND"` | no |
 | cluster\_autoscaler\_enabled | Set true to label the node group so that the [Kubernetes Cluster Autoscaler](https://github.com/kubernetes/autoscaler/blob/master/cluster-autoscaler/cloudprovider/aws/README.md#auto-discovery-setup) will discover and autoscale it | `bool` | `null` | no |
 | cluster\_name | The name of the EKS cluster | `string` | n/a | yes |
 | context | Single object for setting entire context at once.<br>See description of individual variables for details.<br>Leave string and numeric variables as `null` to use default value.<br>Individual variable settings (non-null) override settings in context object,<br>except for attributes, tags, and additional\_tag\_map, which are merged. | <pre>object({<br>    enabled             = bool<br>    namespace           = string<br>    environment         = string<br>    stage               = string<br>    name                = string<br>    delimiter           = string<br>    attributes          = list(string)<br>    tags                = map(string)<br>    additional_tag_map  = map(string)<br>    regex_replace_chars = string<br>    label_order         = list(string)<br>    id_length_limit     = number<br>  })</pre> | <pre>{<br>  "additional_tag_map": {},<br>  "attributes": [],<br>  "delimiter": null,<br>  "enabled": true,<br>  "environment": null,<br>  "id_length_limit": null,<br>  "label_order": [],<br>  "name": null,<br>  "namespace": null,<br>  "regex_replace_chars": null,<br>  "stage": null,<br>  "tags": {}<br>}</pre> | no |

main.tf

@@ -66,6 +66,7 @@ locals {
     disk_size       = local.use_launch_template ? null : var.disk_size
     instance_types  = local.use_launch_template ? null : var.instance_types
     ami_type        = local.launch_template_ami == "" ? var.ami_type : null
+    capacity_type   = var.capacity_type
     labels          = var.kubernetes_labels == null ? {} : var.kubernetes_labels
     release_version = local.launch_template_ami == "" ? var.ami_release_version : null
     version         = length(compact([local.launch_template_ami, var.ami_release_version])) == 0 ? var.kubernetes_version : null
@@ -99,6 +100,7 @@ resource "random_pet" "cbd" {
     ami_type        = local.ng.ami_type
     release_version = local.ng.release_version
     version         = local.ng.version
+    capacity_type   = local.ng.capacity_type
 
     need_remote_access = local.ng.need_remote_access
     ec2_ssh_key        = local.ng.need_remote_access ? local.ng.ec2_ssh_key : "handled by launch template"
@@ -142,6 +144,8 @@ resource "aws_eks_node_group" "default" {
   release_version = local.ng.release_version
   version         = local.ng.version
 
+  capacity_type = local.ng.capacity_type
+
   tags = local.ng.tags
 
   scaling_config {
@@ -203,6 +207,8 @@ resource "aws_eks_node_group" "cbd" {
   release_version = local.ng.release_version
   version         = local.ng.version
 
+  capacity_type = local.ng.capacity_type
+
   tags = local.ng.tags
 
   scaling_config {

variables.tf

@@ -117,6 +117,15 @@ variable "instance_types" {
   }
 }
 
+variable "capacity_type" {
+  type        = string
+  default     = "ON_DEMAND"
+  description = <<-EOT
+  Type of capacity associated with the EKS Node Group. Valid values: ON_DEMAND, SPOT. 
+  Terraform will only perform drift detection if a configuration value is provided.
+  EOT
+}
+
 variable "kubernetes_labels" {
   type        = map(string)
   description = <<-EOT