Add boolean variable use_spot_instance (#10)

* Add variable use_spot_instance

* Set on_demand_base_capacity

Author: Duy Pham

README.md

@@ -155,7 +155,8 @@ This is an open source software. Feel free to open issues and pull requests.
 |------|-------------|:----:|:-----:|:-----:|
 | extra\_user\_data | Extra script to run in the NAT instance | string | `""` | no |
 | image\_id | AMI of the NAT instance. Default to the latest Amazon Linux 2 | string | `""` | no |
-| instance\_types | Candidates of spot instance type for the NAT instance. This is used in the mixed instances policy | list | `[ "t3.nano", "t3a.nano" ]` | no |
+| instance\_types | Candidates of instance type for the NAT instance. This is used in the mixed instances policy | list | `[ "t3.nano", "t3a.nano" ]` | no |
+| use_spot_instance | Whether to use spot or on-demand EC2 instance | boolean | true | no |
 | key\_name | Name of the key pair for the NAT instance. You can set this to assign the key pair to the NAT instance | string | `""` | no |
 | name | Name for all the resources as identifier | string | n/a | yes |
 | private\_route\_table\_ids | List of ID of the route tables for the private subnets. You can set this to assign the each default route to the NAT instance | list | `[]` | no |

main.tf

@@ -112,7 +112,8 @@ resource "aws_autoscaling_group" "this" {
 
   mixed_instances_policy {
     instances_distribution {
-      on_demand_percentage_above_base_capacity = 0
+      on_demand_base_capacity                  = var.use_spot_instance ? 0 : 1
+      on_demand_percentage_above_base_capacity = var.use_spot_instance ? 0 : 100
     }
     launch_template {
       launch_template_specification {

variables.tf

@@ -34,6 +34,11 @@ variable "instance_types" {
   default     = ["t3.nano", "t3a.nano"]
 }
 
+variable "use_spot_instance" {
+  description = "Whether to use spot or on-demand EC2 instance"
+  default     = true
+}
+
 variable "key_name" {
   description = "Name of the key pair for the NAT instance. You can set this to assign the key pair to the NAT instance"
   default     = ""