Added lifecycle hooks to asg removing asg-lifecycle

Author: qrilka

examples/asg-lifecycle-hooks/README.md

@@ -1,5 +1,9 @@
 # Example to test basic ASG integration with lifecycle hooks
 
+This example uses [lifecycled](https://github.com/buildkite/lifecycled) to process
+lifecycle events. As of version 3.0.2 `lifecycled` supports only instance termination
+events and reacts to a termination event for a node it is running on.
+
 ## Environment creation and deployment
 
 To use this example set up AWS credentials and then run the commands in the
@@ -35,10 +39,16 @@ running. You can check the status of the service using
 systemctl status lifecycled.service
 ```
 
+Output from a handler could be seen in the service log e.g. by using
+
+```
+journalctl -f -u lifecycled.service
+```
+
 
 ## Test the Notification
 
-To generate a notification for a launch event, update the Auto Scaling group by increasing the desired capacity of the Auto Scaling group by 1. You receive a notification within a few minutes after instance launch.
+To generate a notification for a termination event, update the Auto Scaling group by decreasing the desired capacity of the Auto Scaling group by 1. You receive a notification within a few minutes after instance termination.
 
 To change the desired capacity using the console
 
@@ -54,8 +64,7 @@ To change the desired capacity using the console
 
     Choose Save.
 
-    After a few minutes, you'll see that the lifecycle-handler.sh script will be executed and it's side effect operation will be performed.
-
+    After a few minutes, you'll see that the lifecycle-handler.sh script will be executed and it's side effect operation will be performed: in the log of lifecycled.service you'll see a line with something like "hello from the handler, received autoscaling:EC2_INSTANCE_TERMINATING i-01234567890123456"
 
 ## Destruction
 
@@ -67,5 +76,5 @@ make clean
 ```
 
 ## Notes
-- This example was last tested with `Terraform v0.11.11`
+- This example was last tested with `Terraform v0.12.4`
 - This example assumes AWS credentials setup with access to the **us-east-2** region.

examples/asg-lifecycle-hooks/cloud-config.yml

@@ -30,14 +30,13 @@ write_files:
     content: |
      #! /usr/bin/bash
 
-      set -euo pipefail
+     set -euo pipefail
 
-      EC2_INSTANCE_ID="`wget -q -O - http://169.254.169.254/latest/meta-data/instance-id`"
-      aws elb deregister-instances-from-load-balancer --load-balancer-name ${elb_name} --instances $EC2_INSTANCE_ID --region ${region}
-      echo "hello from the handler"
-      wget http://18.222.32.132:3000
-      sleep 120
-      echo "goodbye from the handler"
+     echo "hello from the handler, received $${@-nothing}"
+     curl http://localhost:3000
+     echo
+     sleep 10
+     echo "goodbye from the handler"
 runcmd:
   - |
     wget https://github.com/buildkite/lifecycled/releases/download/v3.0.2/lifecycled-linux-amd64
@@ -51,4 +50,4 @@ runcmd:
     wget https://www.busybox.net/downloads/binaries/1.28.1-defconfig-multiarch/busybox-x86_64
     chmod +x busybox-x86_64
     nohup ./busybox-x86_64 httpd -f -p 3000 &
-    wget http://18.222.32.132:3000
+    curl http://localhost:3000

examples/asg-lifecycle-hooks/main.tf

@@ -20,15 +20,15 @@ data "template_file" "main" {
 
   vars = {
     region          = data.aws_region.current.name
-    stack_name      = "${var.lifecycle_name_prefix}-asg"
+    stack_name      = "${var.name_prefix}-asg"
     lifecycle_topic = aws_sns_topic.main.arn
     elb_name        = aws_elb.web.name
   }
 }
 
 module "vpc" {
   source      = "../../modules/vpc-scenario-1"
-  name_prefix = var.name
+  name_prefix = var.name_prefix
   region      = var.region
   cidr        = var.vpc_cidr
   azs         = local.azs
@@ -67,15 +67,15 @@ data "aws_ami" "linux2" {
 }
 
 resource "aws_key_pair" "main" {
-  key_name   = var.name
+  key_name   = var.name_prefix
   public_key = file(var.ssh_pubkey)
 }
 
 # Security group for the elastic load balancer, web instance, only accessible from ELB
 module "elb-sg" {
   source      = "../../modules/security-group-base"
-  description = "Allow public access to ELB in ${var.name}"
-  name        = "${var.name}-elb"
+  description = "Allow public access to ELB in ${var.name_prefix}"
+  name        = "${var.name_prefix}-elb"
   vpc_id      = module.vpc.vpc_id
 }
 
@@ -111,7 +111,7 @@ module "web-http-elb-sg-rule" {
 
 # Load Balancer
 resource "aws_elb" "web" {
-  name = "${var.name}-elb"
+  name = "${var.name_prefix}-elb"
 
   health_check {
     healthy_threshold   = 2
@@ -144,28 +144,27 @@ resource "aws_sns_topic" "main" {
   name = "${var.name_prefix}-lifecycle"
 }
 
-module "asg-lifecycle" {
-  source                = "../../modules/asg-lifecycle"
-  name_prefix           = var.lifecycle_name_prefix
-  azs                   = local.azs
-  elb_names             = [aws_elb.web.name]
-  subnet_ids            = module.vpc.public_subnet_ids
-  instance_count        = "2"
-  instance_ami          = data.aws_ami.linux2.id
-  instance_type         = "t2.nano"
-  instance_key          = aws_key_pair.main.key_name
-  elb_sg_id             = module.elb-sg.id
-  asg_template_file     = data.template_file.main.rendered
-  sns_topic_arn         = aws_sns_topic.main.arn
-  vpc_id                = module.vpc.vpc_id
-  elb_arn               = aws_elb.web.arn
-  aws_role_arn          = aws_iam_role.lifecycle_hook.arn
-  aws_instance_ec2_name = aws_iam_instance_profile.ec2.name
-  aws_sg_id             = aws_security_group.main.id
+module "asg" {
+  source             	  = "../../modules/asg"
+  name_prefix        	  = var.name_prefix
+  azs                	  = local.azs
+  elb_names          	  = [aws_elb.web.name]
+  subnet_ids         	  = module.vpc.public_subnet_ids
+  min_nodes          	  = 1
+  max_nodes          	  = 4
+  ami                	  = data.aws_ami.linux2.id
+  instance_type      	  = "t2.nano"
+  key_name           	  = aws_key_pair.main.key_name
+  user_data          	  = data.template_file.main.rendered
+  enable_terminating_hook = true
+  lifecycle_sns_topic_arn = aws_sns_topic.main.arn
+  aws_role_arn       	  = aws_iam_role.lifecycle_hook.arn
+  iam_profile        	  = aws_iam_instance_profile.ec2.name
+  security_group_ids 	  = [module.elb-sg.id, aws_security_group.main.id]
 }
 
 resource "aws_security_group" "main" {
-  name        = "${var.lifecycle_name_prefix}-sg"
+  name        = "${var.name_prefix}-sg"
   description = "Allow access to lifecycled instances"
   vpc_id      = module.vpc.vpc_id
 
@@ -249,12 +248,12 @@ data "aws_iam_policy_document" "permissions" {
 }
 
 resource "aws_iam_instance_profile" "ec2" {
-  name = "${var.lifecycle_name_prefix}-ec2-instance-profile"
+  name = "${var.name_prefix}-ec2-instance-profile"
   role = aws_iam_role.ec2.name
 }
 
 resource "aws_iam_role" "ec2" {
-  name               = "${var.lifecycle_name_prefix}-ec2-role"
+  name               = "${var.name_prefix}-ec2-role"
   assume_role_policy = data.aws_iam_policy_document.ec2_assume.json
 }
 
@@ -278,12 +277,12 @@ data "aws_iam_policy_document" "ec2_assume" {
 
 # Execution role and policies for the lifecycle hook
 resource "aws_iam_role" "lifecycle_hook" {
-  name               = "${var.lifecycle_name_prefix}-lifecycle-role"
+  name               = "${var.name_prefix}-lifecycle-role"
   assume_role_policy = data.aws_iam_policy_document.asg_assume.json
 }
 
 resource "aws_iam_role_policy" "lifecycle_hook" {
-  name   = "${var.lifecycle_name_prefix}-lifecycle-asg-permissions"
+  name   = "${var.name_prefix}-lifecycle-asg-permissions"
   role   = aws_iam_role.lifecycle_hook.id
   policy = data.aws_iam_policy_document.asg_permissions.json
 }

examples/asg-lifecycle-hooks/variables.tf

@@ -3,21 +3,11 @@ variable "extra_tags" {
   default     = {}
 }
 
-variable "lifecycle_name_prefix" {
-  description = "Prefix used for resource names."
-  default     = "lifecycled-eg"
-}
-
 variable "name_prefix" {
   description = "Prefix used for resource names."
   default     = "asg-lc"
 }
 
-variable "name" {
-  description = "name of the project, use as prefix to names of resources created"
-  default     = "test-lifecycle-project"
-}
-
 variable "region" {
   description = "Region where the project will be deployed"
   default     = "us-east-2"

modules/asg-lifecycle/main.tf

@@ -11,6 +11,9 @@ The module supports:
 * the health checks are not yet parametized, (easy to change)
 * the Launch Configuration supports an arbitrary list of security groups
 * `lifecycle` and `create_before_destroy` are used to ensure updates are graceful
+* lifecycle hooks which get enabled using `enable_launching_hook` and/or
+  `enable_terminating_hook`, don't forget to set proper `lifecycle_sns_topic_arn`
+  and `aws_role_arn` for setting up SNS
 * public IPs may be enabled/disabled
 * supports appending `extra_tags`
 * all important details (instance type, ami, key, user data, iam profile) are