Added ASG template, explicit types in module arguments

asg/files/instance-config.yml.tpl

@@ -0,0 +1,2 @@
+#instance-config
+${custom_script}

asg/main.tf

@@ -0,0 +1,292 @@
+/**
+ */
+
+variable "name" {
+  description = "The cluster name, e.g cdn"
+  type = "string"
+}
+
+variable "environment" {
+  description = "Environment tag, e.g prod"
+  type = "string"
+}
+
+variable "vpc_id" {
+  description = "VPC ID"
+  type = "string"
+}
+
+variable "image_id" {
+  description = "AMI Image ID"
+  type = "string"
+}
+
+variable "subnet_ids" {
+  description = "list of subnet IDs"
+  type = "list"
+}
+
+variable "key_name" {
+  description = "SSH key name to use"
+  type = "string"
+}
+
+variable "ingress_cidr" {
+  description = "Comma separated list of ingress cidrs"
+  type = "string"
+}
+
+variable "iam_instance_profile" {
+  description = "Instance profile ARN to use in the launch configuration"
+  type = "string"
+}
+
+variable "region" {
+  description = "AWS Region"
+  type = "string"
+}
+
+variable "availability_zones" {
+  description = "list of AZs"
+  type = "list"
+}
+
+variable "instance_type" {
+  description = "The instance type to use, e.g t2.small"
+  type = "string"
+}
+
+variable "instance_ebs_optimized" {
+  description = "When set to true the instance will be launched with EBS optimized turned on"
+  default     = true
+}
+
+variable "min_size" {
+  description = "Minimum instance count"
+  default     = 3
+}
+
+variable "max_size" {
+  description = "Maxmimum instance count"
+  default     = 100
+}
+
+variable "desired_capacity" {
+  description = "Desired instance count"
+  default     = 3
+}
+
+variable "associate_public_ip_address" {
+  description = "Should created instances be publicly accessible (if the SG allows)"
+  default     = false
+}
+
+variable "custom_script" {
+  description = "Custom instance bootupt script"
+  default     = ""
+  type = "string"
+}
+
+variable "load_balancers" {
+  description = "ASG ELBs"
+  default     = []
+}
+
+variable "health_check_grace_period" {
+  description = "Time (in seconds) after instance comes into service before checking health"
+  default     = 300
+}
+
+variable "target_group_arns" {
+  description = "Application load balancer target group ARN(s)  if any"
+  default     = []
+}
+
+variable "termination_policies" {
+  description = "OldestInstance, NewestInstance, OldestLaunchConfiguration, ClosestToNextInstanceHour, Default"
+  default     = ["OldestLaunchConfiguration", "Default"]
+}
+
+variable "wait_for_capacity_timeout" {
+  description = "A maximum duration that Terraform should wait for ASG instances to be healthy before timing out"
+  default     = "10m"
+}
+
+resource "aws_security_group" "asg" {
+  name        = "${var.name}-asg"
+  vpc_id      = "${var.vpc_id}"
+  description = "Allows traffic from and to the EC2 instances of the ${var.name} ASG"
+
+  ingress {
+    from_port   = 0
+    to_port     = 0
+    protocol    = -1
+    cidr_blocks = ["${split(",", var.ingress_cidr)}"]
+  }
+
+  egress {
+    from_port   = 0
+    to_port     = 0
+    protocol    = -1
+    cidr_blocks = ["0.0.0.0/0"]
+  }
+
+  tags {
+    Name        = "ASG (${var.name})"
+    Environment = "${var.environment}"
+  }
+
+  lifecycle {
+    create_before_destroy = true
+  }
+}
+
+data "template_file" "instance_config" {
+  template = "${file("${path.module}/files/instance-config.yml.tpl")}"
+
+  vars {
+    custom_script = "${var.custom_script}"
+  }
+}
+
+resource "aws_launch_configuration" "main" {
+  name_prefix = "${format("%s-", var.name)}"
+
+  image_id                    = "${var.image_id}"
+  instance_type               = "${var.instance_type}"
+  ebs_optimized               = "${var.instance_ebs_optimized}"
+  iam_instance_profile        = "${var.iam_instance_profile}"
+  key_name                    = "${var.key_name}"
+  security_groups             = ["${aws_security_group.asg.id}"]
+  user_data                   = "${data.template_file.instance_config.rendered}"
+  associate_public_ip_address = "${var.associate_public_ip_address}"
+
+  lifecycle {
+    create_before_destroy = true
+  }
+}
+
+resource "aws_autoscaling_group" "main" {
+  name = "${var.name}"
+
+  availability_zones        = ["${var.availability_zones}"]
+  vpc_zone_identifier       = ["${var.subnet_ids}"]
+  launch_configuration      = "${aws_launch_configuration.main.id}"
+  min_size                  = "${var.min_size}"
+  max_size                  = "${var.max_size}"
+  desired_capacity          = "${var.desired_capacity}"
+  health_check_grace_period = "${var.health_check_grace_period}"
+  health_check_type         = "ELB"
+  load_balancers            = ["${var.load_balancers}"]
+  target_group_arns         = ["${var.target_group_arns}"]
+  termination_policies      = "${var.termination_policies}"
+  wait_for_capacity_timeout = "${var.wait_for_capacity_timeout}"
+
+  tag {
+    key                 = "Name"
+    value               = "${var.name}"
+    propagate_at_launch = true
+  }
+
+  tag {
+    key                 = "Cluster"
+    value               = "${var.name}"
+    propagate_at_launch = true
+  }
+
+  tag {
+    key                 = "Environment"
+    value               = "${var.environment}"
+    propagate_at_launch = true
+  }
+
+  lifecycle {
+    create_before_destroy = true
+  }
+}
+
+resource "aws_autoscaling_policy" "scale_up" {
+  name                   = "${var.name}-scaleup"
+  scaling_adjustment     = 1
+  adjustment_type        = "ChangeInCapacity"
+  cooldown               = 300
+  autoscaling_group_name = "${aws_autoscaling_group.main.name}"
+
+  lifecycle {
+    create_before_destroy = true
+  }
+}
+
+resource "aws_autoscaling_policy" "scale_down" {
+  name                   = "${var.name}-scaledown"
+  scaling_adjustment     = -1
+  adjustment_type        = "ChangeInCapacity"
+  cooldown               = 300
+  autoscaling_group_name = "${aws_autoscaling_group.main.name}"
+
+  lifecycle {
+    create_before_destroy = true
+  }
+}
+
+resource "aws_cloudwatch_metric_alarm" "cpu_high" {
+  alarm_name          = "${var.name}-cpureservation-high"
+  comparison_operator = "GreaterThanOrEqualToThreshold"
+  evaluation_periods  = "2"
+  metric_name         = "CPUUtilization"
+  namespace           = "AWS/EC2"
+  period              = "300"
+  statistic           = "Maximum"
+  threshold           = "60"
+
+  dimensions {
+    AutoScalingGroupName = "${aws_autoscaling_group.main.name}"
+  }
+
+  alarm_description = "Scale up if the cpu reservation is above 60% for 10 minutes"
+  alarm_actions     = ["${aws_autoscaling_policy.scale_up.arn}"]
+
+  lifecycle {
+    create_before_destroy = true
+  }
+
+  # This is required to make cloudwatch alarms creation sequential, AWS doesn't
+  # support modifying alarms concurrently.
+  depends_on = ["aws_autoscaling_group.main"]
+}
+
+resource "aws_cloudwatch_metric_alarm" "cpu_low" {
+  alarm_name          = "${var.name}-cpureservation-low"
+  comparison_operator = "LessThanOrEqualToThreshold"
+  evaluation_periods  = "2"
+  metric_name         = "CPUUtilization"
+  namespace           = "AWS/EC2"
+  period              = "300"
+  statistic           = "Maximum"
+  threshold           = "10"
+
+  dimensions {
+    AutoScalingGroupName = "${aws_autoscaling_group.main.name}"
+  }
+
+  alarm_description = "Scale down if the cpu reservation is below 10% for 10 minutes"
+  alarm_actions     = ["${aws_autoscaling_policy.scale_down.arn}"]
+
+  lifecycle {
+    create_before_destroy = true
+  }
+
+  # This is required to make cloudwatch alarms creation sequential, AWS doesn't
+  # support modifying alarms concurrently.
+  depends_on = ["aws_cloudwatch_metric_alarm.cpu_high"]
+}
+
+// The asg name, e.g cdn
+output "name" {
+  value = "${var.name}"
+}
+
+// The asg security group ID.
+output "security_group_id" {
+  value = "${aws_security_group.asg.id}"
+}

bastion/main.tf

@@ -24,14 +24,17 @@
 variable "instance_type" {
   default     = "t2.micro"
   description = "Instance type, see a list at: https://aws.amazon.com/ec2/instance-types/"
+  type = "string"
 }
 
 variable "region" {
   description = "AWS Region, e.g us-west-2"
+  type = "string"
 }
 
 variable "security_groups" {
-  description = "a comma separated lists of security group IDs"
+  description = "List of security group IDs"
+  type = "list"
 }
 
 variable "vpc_id" {
@@ -63,7 +66,7 @@ resource "aws_instance" "bastion" {
   instance_type          = "${var.instance_type}"
   subnet_id              = "${var.subnet_id}"
   key_name               = "${var.key_name}"
-  vpc_security_group_ids = ["${split(",",var.security_groups)}"]
+  vpc_security_group_ids = ["${var.security_groups}"]
   monitoring             = true
   user_data              = "${file(format("%s/user_data.sh", path.module))}"
 

dns/main.tf

@@ -40,5 +40,5 @@ output "zone_id" {
 
 // A comma separated list of the zone name servers.
 output "name_servers" {
-  value = "${join(",",aws_route53_zone.main.name_servers)}"
+  value = ["${aws_route53_zone.main.name_servers}"]
 }

ecs-cluster/main.tf

@@ -51,7 +51,8 @@ variable "key_name" {
 }
 
 variable "security_groups" {
-  description = "Comma separated list of security groups"
+  description = "List of security groups"
+  type = "list"
 }
 
 variable "iam_instance_profile" {
@@ -135,7 +136,7 @@ resource "aws_security_group" "cluster" {
     from_port       = 0
     to_port         = 0
     protocol        = -1
-    security_groups = ["${split(",", var.security_groups)}"]
+    security_groups = ["${var.security_groups}"]
   }
 
   egress {

elb/main.tf

@@ -6,42 +6,78 @@
 
 variable "name" {
   description = "ELB name, e.g cdn"
+  type = "string"
 }
 
 variable "subnet_ids" {
-  description = "Comma separated list of subnet IDs"
+  description = "List of subnet IDs"
+  type = "list"
 }
 
 variable "environment" {
   description = "Environment tag, e.g prod"
+  type = "string"
 }
 
 variable "port" {
   description = "Instance port"
+  type = "string"
 }
 
 variable "security_groups" {
-  description = "Comma separated list of security group IDs"
+  description = "List of security group IDs"
+  type = "list"
 }
 
 variable "dns_name" {
   description = "Route53 record name"
+  type = "string"
 }
 
 variable "healthcheck" {
   description = "Healthcheck path"
+  type = "string"
+}
+
+variable "healthcheck_healthy_threshold" {
+  description = "Number of consecutive health check successes before declaring an EC2 instance healthy."
+  default     = 2
+}
+
+variable "healthcheck_unhealthy_threshold" {
+  description = "Number of consecutive health check failures before declaring an EC2 instance unhealthy."
+  default     = 2
+}
+
+variable "healthcheck_timeout" {
+  description = "Time to wait when receiving a response from the health check (2 sec  60 sec)."
+  default     = 5
+}
+
+variable "healthcheck_interval" {
+  description = "Amount of time between health checks (5 sec  300 sec)"
+  default     = 30
 }
 
 variable "protocol" {
   description = "Protocol to use, HTTP or TCP"
+  type = "string"
 }
 
 variable "zone_id" {
   description = "Route53 zone ID to use for dns_name"
+  type = "string"
 }
 
 variable "log_bucket" {
   description = "S3 bucket name to write ELB logs into"
+  type = "string"
+}
+
+# https://docs.aws.amazon.com/elasticloadbalancing/latest/classic/config-idle-timeout.html?icmpid=docs_elb_console
+variable "idle_timeout" {
+  description = "ELB idle connection timeout"
+  default     = 30
 }
 
 /**
@@ -53,26 +89,26 @@ resource "aws_elb" "main" {
 
   internal                  = true
   cross_zone_load_balancing = true
-  subnets                   = ["${split(",", var.subnet_ids)}"]
-  security_groups           = ["${split(",",var.security_groups)}"]
+  subnets                   = ["${var.subnet_ids}"]
+  security_groups           = ["${var.security_groups}"]
 
-  idle_timeout                = 30
+  idle_timeout                = "${var.idle_timeout}"
   connection_draining         = true
   connection_draining_timeout = 15
 
   listener {
-    lb_port           = 80
+    lb_port           = "${var.port}"
     lb_protocol       = "${var.protocol}"
     instance_port     = "${var.port}"
     instance_protocol = "${var.protocol}"
   }
 
   health_check {
-    healthy_threshold   = 2
-    unhealthy_threshold = 2
-    timeout             = 5
+    healthy_threshold   = "${var.healthcheck_healthy_threshold}"
+    unhealthy_threshold = "${var.healthcheck_unhealthy_threshold}"
+    timeout             = "${var.healthcheck_timeout}"
     target              = "${var.protocol}:${var.port}${var.healthcheck}"
-    interval            = 30
+    interval            = "${var.healthcheck_interval}"
   }
 
   access_logs {
@@ -102,6 +138,11 @@ resource "aws_route53_record" "main" {
  * Outputs.
  */
 
+// Instance port
+output "port" {
+  value = "${var.port}"
+}
+
 // The ELB name.
 output "name" {
   value = "${aws_elb.main.name}"
@@ -126,3 +167,4 @@ output "fqdn" {
 output "zone_id" {
   value = "${aws_elb.main.zone_id}"
 }
+

iam-role/main.tf

@@ -6,30 +6,46 @@ variable "environment" {
   description = "The name of the environment for this stack"
 }
 
-resource "aws_iam_role" "default_ecs_role" {
-  name = "ecs-role-${var.name}-${var.environment}"
+variable "ecs_role_services" {
+  description = ""
+  default     = "\"ec2.amazonaws.com\""
+}
+
+variable "aws_iam_role_policy_allow" {
+  description = ""
+  default     = "\"autoscaling:*\",\"cloudwatch:*\""
+}
 
-  assume_role_policy = <<EOF
+data "template_file" "aws_iam_role" {
+  template = <<EOF
 {
   "Version": "2008-10-17",
   "Statement": [
     {
       "Action": "sts:AssumeRole",
       "Principal": {
         "Service": [
-          "ecs.amazonaws.com",
-          "ec2.amazonaws.com"
+          $${ecs_role_services}
         ]
       },
       "Effect": "Allow"
     }
   ]
 }
 EOF
+
+  vars {
+    ecs_role_services = "${var.ecs_role_services}"
+  }
+}
+
+resource "aws_iam_role" "default_ecs_role" {
+  name               = "ecsrole-${var.name}-${var.environment}"
+  assume_role_policy = "${data.template_file.aws_iam_role.rendered}"
 }
 
 resource "aws_iam_role_policy" "default_ecs_service_role_policy" {
-  name = "ecs-service-role-policy-${var.name}-${var.environment}"
+  name = "ecs-servicerole-policy-${var.name}-${var.environment}"
   role = "${aws_iam_role.default_ecs_role.id}"
 
   policy = <<EOF
@@ -41,9 +57,11 @@ resource "aws_iam_role_policy" "default_ecs_service_role_policy" {
       "Action": [
         "ec2:AuthorizeSecurityGroupIngress",
         "ec2:Describe*",
+        "s3:*",
         "elasticloadbalancing:DeregisterInstancesFromLoadBalancer",
         "elasticloadbalancing:Describe*",
-        "elasticloadbalancing:RegisterInstancesWithLoadBalancer"
+        "elasticloadbalancing:RegisterInstancesWithLoadBalancer",
+        "cloudwatch:*"
       ],
       "Resource": "*"
     }
@@ -52,30 +70,15 @@ resource "aws_iam_role_policy" "default_ecs_service_role_policy" {
 EOF
 }
 
-resource "aws_iam_role_policy" "default_ecs_instance_role_policy" {
-  name = "ecs-instance-role-policy-${var.name}-${var.environment}"
-  role = "${aws_iam_role.default_ecs_role.id}"
-
-  policy = <<EOF
+data "template_file" "aws_iam_role_policy" {
+  template = <<EOF
 {
   "Version": "2012-10-17",
   "Statement": [
     {
       "Effect": "Allow",
       "Action": [
-        "ecs:CreateCluster",
-        "ecs:DeregisterContainerInstance",
-        "ecs:DiscoverPollEndpoint",
-        "ecs:Poll",
-        "ecs:RegisterContainerInstance",
-        "ecs:StartTelemetrySession",
-        "ecs:Submit*",
-        "ecr:GetAuthorizationToken",
-        "ecr:BatchCheckLayerAvailability",
-        "ecr:GetDownloadUrlForLayer",
-        "ecr:BatchGetImage",
-        "ecs:StartTask",
-        "autoscaling:*"
+        $${allow_actions}
       ],
       "Resource": "*"
     },
@@ -85,13 +88,25 @@ resource "aws_iam_role_policy" "default_ecs_instance_role_policy" {
         "logs:CreateLogGroup",
         "logs:CreateLogStream",
         "logs:PutLogEvents",
-        "logs:DescribeLogStreams"
+        "logs:DescribeLogStreams",
+        "cloudwatch:*"
       ],
       "Resource": "arn:aws:logs:*:*:*"
     }
   ]
 }
 EOF
+
+  vars {
+    allow_actions = "${var.aws_iam_role_policy_allow}"
+  }
+}
+
+resource "aws_iam_role_policy" "default_ecs_instance_role_policy" {
+  name = "ecs-instancerole-policy-${var.name}-${var.environment}"
+  role = "${aws_iam_role.default_ecs_role.id}"
+
+  policy = "${data.template_file.aws_iam_role_policy.rendered}"
 }
 
 resource "aws_iam_instance_profile" "default_ecs" {
@@ -100,14 +115,11 @@ resource "aws_iam_instance_profile" "default_ecs" {
   roles = ["${aws_iam_role.default_ecs_role.name}"]
 }
 
-output "default_ecs_role_id" {
-  value = "${aws_iam_role.default_ecs_role.id}"
-}
-
 output "arn" {
   value = "${aws_iam_role.default_ecs_role.arn}"
 }
 
 output "profile" {
   value = "${aws_iam_instance_profile.default_ecs.id}"
 }
+

main.tf

@@ -265,11 +265,6 @@ output "iam_role" {
   value = "${module.iam_role.arn}"
 }
 
-// Default ECS role ID. Useful if you want to add a new policy to that role.
-output "iam_role_default_ecs_role_id" {
-  value = "${module.iam_role.default_ecs_role_id}"
-}
-
 // S3 bucket ID for ELB logs.
 output "log_bucket_id" {
   value = "${module.s3_logs.id}"
@@ -309,13 +304,3 @@ output "vpc_id" {
 output "ecs_cluster_security_group_id" {
   value = "${module.ecs_cluster.security_group_id}"
 }
-
-// Comma separated list of internal route table IDs.
-output "internal_route_tables" {
-  value = "${module.vpc.internal_rtb_id}"
-}
-
-// The external route table ID.
-output "external_route_tables" {
-  value = "${module.vpc.external_rtb_id}"
-}

service/main.tf

@@ -36,11 +36,13 @@ variable "version" {
 }
 
 variable "subnet_ids" {
-  description = "Comma separated list of subnet IDs that will be passed to the ELB module"
+  description = "List of subnet IDs that will be passed to the ELB module"
+  type = "list"
 }
 
 variable "security_groups" {
-  description = "Comma separated list of security group IDs that will be passed to the ELB module"
+  description = "List of security group IDs that will be passed to the ELB module"
+  type = "list"
 }
 
 variable "port" {
@@ -98,6 +100,11 @@ variable "cpu" {
   default     = 512
 }
 
+variable "mount_points" {
+  description = "The raw json on the mount points"
+  default     = "[]"
+}
+
 variable "protocol" {
   description = "The ELB protocol, HTTP or TCP"
   default     = "HTTP"
@@ -155,6 +162,7 @@ module "task" {
   env_vars      = "${var.env_vars}"
   memory        = "${var.memory}"
   cpu           = "${var.cpu}"
+  mount_points  = "${mount_points}"
 
   ports = <<EOF
   [

task/main.tf

@@ -62,6 +62,11 @@ variable "memory" {
   default     = 512
 }
 
+variable "mount_points" {
+  description = "The raw json on the mount points"
+  default     = "[]"
+}
+
 /**
  * Resources.
  */
@@ -88,7 +93,7 @@ resource "aws_ecs_task_definition" "main" {
     "name": "${var.name}",
     "portMappings": ${var.ports},
     "entryPoint": ${var.entry_point},
-    "mountPoints": [],
+    "mountPoints": ${var.mount_points},
     "logConfiguration": {
       "logDriver": "journald",
       "options": {

vpc/main.tf

@@ -1,29 +1,32 @@
 variable "cidr" {
   description = "The CIDR block for the VPC."
+  type = "string"
 }
 
 variable "external_subnets" {
-  description = "List of external subnets"
-  type        = "list"
+  description = "List of subnets"
+  type = "list"
 }
 
 variable "internal_subnets" {
-  description = "List of internal subnets"
-  type        = "list"
-}
-
-variable "environment" {
-  description = "Environment tag, e.g prod"
+  description = "List of subnets"
+  type = "list"
 }
 
 variable "availability_zones" {
   description = "List of availability zones"
-  type        = "list"
+  type = "list"
+}
+
+variable "environment" {
+  description = "Environment tag, e.g prod"
+  type = "string"
 }
 
 variable "name" {
   description = "Name tag, e.g stack"
   default     = "stack"
+  type = "string"
 }
 
 /**
@@ -55,14 +58,14 @@ resource "aws_internet_gateway" "main" {
 }
 
 resource "aws_nat_gateway" "main" {
-  count         = "${length(var.internal_subnets)}"
+  count         = "${length(compact(var.internal_subnets))}"
   allocation_id = "${element(aws_eip.nat.*.id, count.index)}"
   subnet_id     = "${element(aws_subnet.external.*.id, count.index)}"
   depends_on    = ["aws_internet_gateway.main"]
 }
 
 resource "aws_eip" "nat" {
-  count = "${length(var.internal_subnets)}"
+  count = "${length(compact(var.internal_subnets))}"
   vpc   = true
 }
 
@@ -74,7 +77,7 @@ resource "aws_subnet" "internal" {
   vpc_id            = "${aws_vpc.main.id}"
   cidr_block        = "${element(var.internal_subnets, count.index)}"
   availability_zone = "${element(var.availability_zones, count.index)}"
-  count             = "${length(var.internal_subnets)}"
+  count             = "${length(compact(var.internal_subnets))}"
 
   tags {
     Name = "${var.name}-${format("internal-%03d", count.index+1)}"
@@ -85,7 +88,7 @@ resource "aws_subnet" "external" {
   vpc_id                  = "${aws_vpc.main.id}"
   cidr_block              = "${element(var.external_subnets, count.index)}"
   availability_zone       = "${element(var.availability_zones, count.index)}"
-  count                   = "${length(var.external_subnets)}"
+  count                   = "${length(compact(var.external_subnets))}"
   map_public_ip_on_launch = true
 
   tags {
@@ -100,45 +103,37 @@ resource "aws_subnet" "external" {
 resource "aws_route_table" "external" {
   vpc_id = "${aws_vpc.main.id}"
 
+  route {
+    cidr_block = "0.0.0.0/0"
+    gateway_id = "${aws_internet_gateway.main.id}"
+  }
+
   tags {
     Name = "${var.name}-external-001"
   }
 }
 
-resource "aws_route" "external" {
-  route_table_id         = "${aws_route_table.external.id}"
-  destination_cidr_block = "0.0.0.0/0"
-  gateway_id             = "${aws_internet_gateway.main.id}"
-}
-
 resource "aws_route_table" "internal" {
-  count  = "${length(var.internal_subnets)}"
+  count  = "${length(compact(var.internal_subnets))}"
   vpc_id = "${aws_vpc.main.id}"
 
   tags {
     Name = "${var.name}-${format("internal-%03d", count.index+1)}"
   }
 }
 
-resource "aws_route" "internal" {
-  count                  = "${length(compact(var.internal_subnets))}"
-  route_table_id         = "${element(aws_route_table.internal.*.id, count.index)}"
-  destination_cidr_block = "0.0.0.0/0"
-  nat_gateway_id         = "${element(aws_nat_gateway.main.*.id, count.index)}"
-}
-
 /**
  * Route associations
  */
 
 resource "aws_route_table_association" "internal" {
-  count          = "${length(var.internal_subnets)}"
+  count          = "${length(compact(var.internal_subnets))}"
   subnet_id      = "${element(aws_subnet.internal.*.id, count.index)}"
   route_table_id = "${element(aws_route_table.internal.*.id, count.index)}"
 }
 
 resource "aws_route_table_association" "external" {
-  count          = "${length(var.external_subnets)}"
+  count          = "${length(compact(var.external_subnets))}"
   subnet_id      = "${element(aws_subnet.external.*.id, count.index)}"
   route_table_id = "${aws_route_table.external.id}"
 }
@@ -157,7 +152,7 @@ output "external_subnets" {
   value = ["${aws_subnet.external.*.id}"]
 }
 
-// A list of subnet IDs.
+// A comma-separated list of subnet IDs.
 output "internal_subnets" {
   value = ["${aws_subnet.internal.*.id}"]
 }
@@ -172,17 +167,3 @@ output "availability_zones" {
   value = ["${aws_subnet.external.*.availability_zone}"]
 }
 
-// The internal route table ID.
-output "internal_rtb_id" {
-  value = "${join(",", aws_route_table.internal.*.id)}"
-}
-
-// The external route table ID.
-output "external_rtb_id" {
-  value = "${aws_route_table.external.id}"
-}
-
-// The list of EIPs associated with the internal subnets.
-output "internal_nat_ips" {
-  value = ["${aws_eip.nat.*.public_ip}"]
-}

web-service/main.tf

@@ -36,11 +36,13 @@ variable "version" {
 }
 
 variable "subnet_ids" {
-  description = "Comma separated list of subnet IDs that will be passed to the ELB module"
+  description = "List of subnet IDs that will be passed to the ELB module"
+  type = "list"
 }
 
 variable "security_groups" {
-  description = "Comma separated list of security group IDs that will be passed to the ELB module"
+  description = "List of security group IDs that will be passed to the ELB module"
+  type = "list"
 }
 
 variable "port" {