Added lifecycle policy (#7)

* Added lifecycle policy

* Renamed variable from rotate_number to max_image_number

* Applied terraform fmt

* Renamed to max_image_count + updated README

* Modified the logic to be tagged by default

* Applied Terraform fmt

README.md

@@ -40,6 +40,7 @@ module "ecr" {
 | `stage`                      | `default`      | Stage (e.g. `prod`, `dev`, `staging`)                                                                    | Yes           |
 | `name`                       | `admin`        | The Name of the application or solution  (e.g. `bastion` or `portal`)                                    | Yes           |
 | `roles`                      | `[]`           | List of IAM role names that will be granted permissions to use the container registry                    | No (optional) |
+| `max_image_count`            | `7`            | How many Docker Image versions AWS ECR will store | Yes |
 
 
 ## Outputs

main.tf

@@ -143,3 +143,25 @@ resource "aws_iam_instance_profile" "default" {
   name  = "${module.label.id}"
   role  = "${aws_iam_role.default.name}"
 }
+
+resource "aws_ecr_lifecycle_policy" "default" {
+  repository = "${aws_ecr_repository.default.name}"
+
+  policy = <<EOF
+{
+  "rules": [{
+    "rulePriority": 1,
+    "description": "Rotate images when reach ${var.max_image_count} images stored",
+    "selection": {
+      "tagStatus": "tagged",
+      "tagPrefixList": ["${var.stage}"],
+      "countType": "imageCountMoreThan",
+      "countNumber": ${var.max_image_count}
+    },
+    "action": {
+      "type": "expire"
+    }
+  }]
+}
+EOF
+}

variables.tf

@@ -24,3 +24,9 @@ variable "tags" {
   type    = "map"
   default = {}
 }
+
+variable "max_image_count" {
+  type        = "string"
+  description = "How many Docker Image versions AWS ECR will store"
+  default     = "7"
+}