terraform-aws-lifecycle-hook-runner

Overview

This module will add lifecycle hooks to run commands on autoscaling group instances before they terminate, so that you can easily run pre-termination tasks or shutdown scripts before the instance is removed.

Queuing is used to ensure commands are run one at a time in the case you are doing a rolling deployment of infrastructure, such as is used in the create_before_destroy lifecycle.

It uses SSM, Lifecycle hooks, SNS topics, The module will create the IAM policies, SNS topics, Lambda function, and lifecycle hooks. It will create a list in Consul for queuing at /kv/asg/${name} so ensure this is accessible.

Requirements

• A Consul KV store that lambda can write to from your AWS environment
• The AWS SSM agent is installed on your instances
• An Autoscaling Group name to attach this to
• A subnet with a NAT Gateway (for Lambda to reach out to SSM)
• A security group that will allow Lambda to make HTTP requests to consul

Usage

Call this module like below. Take note of the 'commands' format. The commands will be run in the order you place them, one by one.

name Required value to prevent overlap/duplicates if called multiple times

environment Required value you can set to whatever you wish

subnet_ids An array of subnets to put the Lambda function in.

security_group_ids Security group for Lambda to communicate with consul

commands A comma separated string with commands to run on instance termination

consul_url The base consul URL like shown below. It will append the path to this.

autoscaling_group_name Name of your autoscaling group

TF

module "lifecycle_hook" {
  source                      = "github.com/sprutner/terraform-aws-lifecycle-hook-runner"
  name                        = "test"
  environment                 = "${var.environment}"
  subnet_ids                  = "${module.vpc.app_subnets}"
  security_group_ids          = "${aws_security_group.docker.id}"
  commands                    = <<EOF
echo 'test',
echo 'hola'
EOF
  consul_url                  = "http://consul.companyxyz${var.environment}.dev"
  autoscaling_group_name      = "${module.nomad_client.asg_name}"
}