Add example for replacing an existing module

Author: Steven Nemetz

examples/wrapper/README.md

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+Auto Scaling Group wrapper sample
+======================================
+
+This is a sample setup for replacing an existing module
+
+Configuration in this directory creates Launch Configuration and Auto Scaling Group.
+
+Data sources are used to discover existing VPC resources (VPC, subnet and security group) as well as AMI details.
+
+Usage
+=====
+
+To run this example you need to execute:
+
+```bash
+$ terraform init
+$ terraform plan
+$ terraform apply
+```
+
+Note that this example may create resources which cost money. Run `terraform destroy` when you don't need these resources.

examples/wrapper/main.tf

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+provider "aws" {
+  region = "${var.region}"
+
+  # Make it faster by skipping something
+  skip_get_ec2_platforms      = true
+  skip_metadata_api_check     = true
+  skip_region_validation      = true
+  skip_credentials_validation = true
+  skip_requesting_account_id  = true
+}
+
+##############################################################
+# Data sources to get VPC, subnets and security group details
+##############################################################
+data "aws_vpc" "vpc" {
+  tags {
+    Env = "${var.environment}"
+  }
+}
+
+data "aws_subnet_ids" "all" {
+  vpc_id = "${data.aws_vpc.vpc.id}"
+}
+
+data "aws_security_group" "default" {
+  vpc_id = "${data.aws_vpc.vpc.id}"
+  name   = "default"
+}
+
+data "aws_ami" "amazon_linux" {
+  most_recent = true
+
+  filter {
+    name = "name"
+
+    values = [
+      "amzn-ami-hvm-*-x86_64-gp2",
+    ]
+  }
+
+  filter {
+    name = "owner-alias"
+
+    values = [
+      "amazon",
+    ]
+  }
+}
+
+/*
+resource "aws_launch_configuration" "this" {
+  name_prefix     = "${var.stack}_lc"
+}
+resource "aws_autoscaling_group" "this" {
+  launch_configuration  = "${aws_launch_configuration.this.name}"
+  # v0.11.2: lifecycle ignore_changes cannot contain interpolations
+  lifecycle {
+    ignore_changes        = ["desired_capacity"]
+  }
+}
+/**/
+######
+# Launch configuration and autoscaling group
+######
+module "example" {
+  source                      = "../../"
+  name                        = "${var.stack}"
+  associate_public_ip_address = "${var.associate_public_ip_address}"
+  environment                 = "${var.environment}"
+  iam_instance_profile        = "${var.instance_profile_id}"
+  image_id                    = "${data.aws_ami.amazon_linux.id}"
+  instance_type               = "${var.instance_type}"
+  key_name                    = "${var.key_name}"
+  security_groups             = ["${data.aws_security_group.default.id}"]
+  spot_price                  = "${var.spot_price}"
+  target_group_arns           = ["${var.target_group_arns}"]
+  user_data                   = "${var.user_data}"
+
+  enabled_metrics = [
+    "GroupInServiceInstances",
+    "GroupMaxSize",
+    "GroupDesiredCapacity",
+    "GroupTotalInstances",
+  ]
+
+  root_block_device = [
+    {
+      volume_size           = "${var.root_volume_size}"
+      volume_type           = "gp2"
+      delete_on_termination = true
+    },
+  ]
+
+  # Auto scaling group
+  asg_name                  = "${var.stack}_asg"
+  desired_capacity          = "${var.desired_capacity}"
+  health_check_grace_period = "${var.health_check_grace_period}"
+  health_check_type         = "${var.health_check_type}"
+  max_size                  = "${var.max_size}"
+  min_size                  = "${var.min_size}"
+  vpc_zone_identifier       = ["${data.aws_subnet_ids.all.ids}"]
+  wait_for_capacity_timeout = 0
+
+  tags = {
+    Name    = "${var.stack} ASG"
+    Project = "megasecret"
+    Stack   = "${var.stack}"
+  }
+}

examples/wrapper/outputs.tf

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+# Launch configuration
+output "launch_configuration_id" {
+  description = "The ID of the launch configuration"
+  value       = "${module.example.launch_configuration_id}"
+}
+output "launch_configuration_name" {
+  description = "The name of the launch configuration"
+  value       = "${module.example.launch_configuration_name}"
+}
+
+# Autoscaling group
+output "autoscaling_group_id" {
+  description = "The autoscaling group id"
+  value       = "${module.example.autoscaling_group_id}"
+}
+output "autoscaling_group_name" {
+  description = "The autoscaling group name"
+  value       = "${module.example.autoscaling_group_name}"
+}

examples/wrapper/variables.tf

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+variable "environment" {
+  default = "one"
+}
+
+variable "region" {
+  default = "us-west-2"
+}
+
+variable "associate_public_ip_address" {
+  description = "Add a public IP address"
+  default     = false
+}
+variable "desired_capacity" {
+  description = "Desired number of instances"
+  default     = 1
+}
+
+variable "health_check_grace_period" {
+  description = "Auto Scaling Group health check grace period in seconds. Time allowed before starting to test the health check"
+  default     = "300"
+}
+variable "health_check_type" {
+  description = "Healthcheck type"
+  default        = "ELB"
+}
+variable "instance_profile_id" {
+  description = "Instance profile ID"
+  default     = ""
+}
+variable "instance_type" {
+  description = "Instance type"
+  default     = "t2.micro"
+}
+variable "key_name" {
+  description = "SSH key name to use"
+  default     = "devops20170606"
+}
+variable "max_size" {
+  description = "Maximum number of instances"
+  default     = 2
+}
+variable "min_size" {
+  description = "Minimum number of instances"
+  default     = 1
+}
+variable "root_volume_size" {
+  description = "Size of the root volume"
+  default     = 8
+}
+variable "spot_price" {
+  description = "Spot price. Set to false to not use spot pricing"
+  default     = false
+}
+variable "stack" {
+  description = "Name of the service stack"
+  default     = "wrapper-test"
+}
+variable "tags" {
+  description = "Map of tags"
+  type        = "map"
+  default     = {}
+}
+variable "target_group_arns" {
+  description = "List of target group ARNs"
+  type        = "list"
+  default     = []
+}
+variable "user_data" {
+  description = "User data script"
+  default     = " "
+}