crisp.aws_cloudformation_asg

Crisp AWS CloudFormation AutoScalingGroup

This role creates a AWS AutoScalingGroup and a ElasticLoadBalancer. The ASG will start a Docker image of your choice.

Most of the resources are created by CloudFormation. The Route 53 DNS entry is outside the CloudFormation stack because it acts as a pointer between different ELBs (inside stacks) and can not be modified this way if it was inside a stack.

The main upside of using CloudFormation is that cleanup of old resources is much easier. However, the Ansible module for querying which stacks exists is not very nice. It returns a hard-to-use data structure (for my use-case) and offers very little querying options.

Every time the playbook is run it will:

• Create a new CloudFormation stack containing:
  • A new SecurityGroup for the instances
  • A new SecurityGroup for the ElasticLoadBalancer
  • A new LaunchConfiguration for the AutoScalingGroup
  • A new TargetGroup for the AutoScalingGroup
  • A new AutoScalingGroup
  • A new ElasticLoadBalancer
  • A new Listener for the ElasticLoadBalancer
• Create/update the DNS alias to point to the new load balancer
• Delete (cleanup) any old stacks created by this role

The main benefit of this is that all infrastructure is replaced on every deployment.

Requirements

AWS credentials.

Packages:

• boto3

Role Variables

• vpc - the AWS VPC identifier (your vpc)
• region - the AWS region to deploy to (example: eu-west-1)
• subnets - a list of subnets to deploy to. Must be at least 2. (needs to exist already)
• aws_key - the instance key which can be used to log in to the created instances (needs to exist already)
• route53_zone - the Route 53 zone where you want to create your DNS entry. (needs to exist already)
• instance_profile - the name of the instance profile (or IAM Role) that the created instances will get. (needs to exist already)

Required environment variables:

• AWS_ACCESS_KEY_ID
• AWS_SECRET_ACCESS_KEY

Dependencies

Not dependent on any other role.

Example Playbook

- hosts: localhost
  connection: local
  gather_facts: yes  # needed for ansible_date_time
  roles:
    - role: betrcode.aws_cloudformation_asg
      docker_image: "nginx:latest"

License

MIT

Author Information

Max Wenzin, partner at Crisp

https://www.crisp.se/konsulter/max-wenzin