Variables - min and max task count for autoscaling (#10)

* min and max task count for autoscaling

* additional scaling parameters

* removed duplicated parameters

README.md

@@ -19,7 +19,7 @@ module "ecs" {
 
   alb_target_group_arn = "arn:aws:elasticloadbalancing:< region >:< account ID >:targetgroup/< target group name >/3b4e9fbf82439af5"
   container_port       = "80"
-  
+
   availability_zones = "${var.availability_zones}"
 
   container_definitions = <<EOF
@@ -53,7 +53,6 @@ EOF
 | container\_port | exposed port in container | string | `80` | no |
 | ecs\_cluster\_id | ID of existing ECS cluster (if want to attach service and etc to existing cluster) | string | `none` | no |
 | environment | Environment name is used to identify resources | string | `env` | no |
-| minimum\_service\_capacity | The number of instances of the task definition to place and keep running | string | `1` | no |
 | health\_check\_grace\_period\_seconds | Seconds to ignore failing load balancer health checks on newly instantiated tasks | string | `30` | no |
 | project | Project name is used to identify resources | string | `test` | no |
 | service | Service name (will be used as family name in task definition) | string | `SuperService` | no |
@@ -65,6 +64,10 @@ EOF
 | launch\_type | Launch type for ECS (FARGATE or EC2 )  | string | `FARGATE` | no |
 | volume\_type | Volume type for EC2  | string | `standard` | no |
 | volume\_size | Volume size for EC2  | string | `100` | no |
+| autoscaling\_min\_capacity | Amount of min running task or EC2 instances | string | `1` | no |
+| autoscaling\_max\_capacity | Amount of max running task or EC2 instances  | string | `10` | no |
+| autoscaling\_cpu\_high\_threshold | Autoscaling CPU threshold for scale-up  | string | `40` | no |
+| autoscaling\_cpu\_low\_threshold | Autoscaling CPU threshold for scale-down  | string | `40` | no |
 | availability\_zones | List of availability zones which will be provisined by autoscailing group  | list | `[]` | yes |
 | vpc\_id | The ID of VPC | string | - | yes |
 
@@ -109,4 +112,4 @@ EOF
 
 ## License
 
-Apache2.0 Licensed. See [LICENSE](https://github.com/lean-delivery/tf-module-aws-ecs/tree/master/LICENSE) for full details.
+Apache2.0 Licensed. See [LICENSE](https://github.com/lean-delivery/tf-module-aws-ecs/tree/master/LICENSE) for full details.

autoscaling.tf

@@ -7,7 +7,7 @@ resource "aws_cloudwatch_metric_alarm" "cpu-high" {
   evaluation_periods  = "1"
   namespace           = "AWS/ECS"
   period              = "60"
-  threshold           = "50"
+  threshold           = "${var.autoscaling_cpu_high_threshold}"
 
   dimensions {
     ClusterName = "${local.ecs_cluster_name}"
@@ -26,7 +26,7 @@ resource "aws_cloudwatch_metric_alarm" "cpu-low" {
   evaluation_periods  = "2"
   namespace           = "AWS/ECS"
   period              = "60"
-  threshold           = "40"
+  threshold           = "${var.autoscaling_cpu_low_threshold}"
 
   dimensions {
     ClusterName = "${local.ecs_cluster_name}"
@@ -45,7 +45,7 @@ resource "aws_cloudwatch_metric_alarm" "cpu-high_ec2" {
   evaluation_periods  = "1"
   namespace           = "AWS/EC2"
   period              = "60"
-  threshold           = "40"
+  threshold           = "${var.autoscaling_cpu_high_threshold}"
 
   dimensions {
     AutoScalingGroupName = "${aws_autoscaling_group.autoscaling-group.name}"
@@ -64,7 +64,7 @@ resource "aws_cloudwatch_metric_alarm" "cpu-low_ec2" {
   evaluation_periods  = "2"
   namespace           = "AWS/EC2"
   period              = "60"
-  threshold           = "40"
+  threshold           = "${var.autoscaling_cpu_low_threshold}"
 
   dimensions {
     AutoScalingGroupName = "${aws_autoscaling_group.autoscaling-group.name}"
@@ -117,8 +117,8 @@ resource "aws_appautoscaling_policy" "scale_policy_low" {
 }
 
 resource "aws_appautoscaling_target" "ecs_target" {
-  max_capacity = 10
-  min_capacity = 1
+  max_capacity = "${var.autoscaling_max_capacity}"
+  min_capacity = "${var.autoscaling_min_capacity}"
   resource_id  = "service/${local.ecs_cluster_name}/${aws_ecs_service.this.name}"
 
   ### https://docs.aws.amazon.com/autoscaling/application/userguide/application-auto-scaling-service-linked-roles.html
@@ -148,9 +148,9 @@ resource "aws_autoscaling_policy" "scale_policy_low_ec2" {
 
 resource "aws_autoscaling_group" "autoscaling-group" {
   name             = "${var.service}-autoscaling-group"
-  max_size         = "3"
-  min_size         = "1"
-  desired_capacity = "1"
+  max_size         = "${var.autoscaling_max_capacity}"
+  min_size         = "${var.autoscaling_min_capacity}"
+  desired_capacity = "${var.autoscaling_min_capacity}"
 
   availability_zones   = ["${var.availability_zones}"]
   vpc_zone_identifier  = ["${var.subnets}"]

ecs-cluster.tf

@@ -41,7 +41,7 @@ resource "aws_ecs_service" "this" {
   deployment_maximum_percent         = "200"
   deployment_minimum_healthy_percent = "100"
 
-  desired_count                     = "${var.minimum_service_capacity}"
+  desired_count                     = "${var.autoscaling_min_capacity}"
   health_check_grace_period_seconds = "${var.health_check_grace_period_seconds}"
 
   network_configuration {

variables.tf

@@ -45,11 +45,6 @@ variable "container_memory" {
   default     = "1024"
 }
 
-variable "minimum_service_capacity" {
-  description = "The number of instances of the task definition to place and keep running"
-  default     = "1"
-}
-
 variable "health_check_grace_period_seconds" {
   description = "Seconds to ignore failing load balancer health checks on newly instantiated tasks to prevent premature shutdown"
   default     = "30"
@@ -111,7 +106,7 @@ variable "key-pair-name" {
 }
 
 variable "instance_type" {
-  description = "ARN of target group"
+  description = "EC2 instance type"
   type        = "string"
   default     = "t2.small"
 }
@@ -137,3 +132,23 @@ variable "availability_zones" {
   description = "List of availability zones which will be provisined by autoscailing group"
   type        = "list"
 }
+
+variable "autoscaling_min_capacity" {
+  description = "Amount of min running task or EC2 instances"
+  default     = "1"
+}
+
+variable "autoscaling_max_capacity" {
+  description = "Amount of max running task or EC2 instances"
+  default     = "10"
+}
+
+variable "autoscaling_cpu_high_threshold" {
+  description = "Autoscaling CPU threshold for scale-up"
+  default     = "50"
+}
+
+variable "autoscaling_cpu_low_threshold" {
+  description = "Autoscaling CPU threshold for scale-down"
+  default     = "40"
+}