/autoscaling-ansible

MIT LicenseMIT

autoscaling-ansible

This repo contains samples that demonstrate various options for using Ansible in conjunction with EC2 AutoScaling groups.

  • Option 1: Run Ansible using AWS SSM State Manager
  • Option 2: Set up EC2 instances to use ansible-pull

Run Ansible using AWS SSM State Manager

This sample makes of AWS SSM State Manager and AWS SSM agent to ensure that all instances have the correct, latest Ansible configuration. This approach has the following benefits:

  • Configuation can be associated to a target group based on presence of a specific tag.
  • It can be applied to pre-existing instances (as long as the instances are running ssm agent)
  • Any new instances that are created in an ASG are automatically detected and configured.
  • SSM State Manager will automatically install Ansible on new instances before attempting to use Ansible to configure them.
  • Changes to the config can be pushed to the entire instance target group immediately.
  • You can control the rate at which config updates are rolled out.
  • Optionally, you can set up a cron schedule to verify that all instances are compliant with latest config, and to apply a config update if not.
  • You can control the error threshold above which an execution should stop.
  • Execution history and logs are recorded, with logs stored on S3.

For more info see:

Setup instructions

  1. Create an S3 bucket to hold the Ansible configuration
  2. Create a folder ansible/ in the bucket
  3. Upload the file ssm-state-manager/ssm-playbook.yml to the ansible/ folder in the bucket.
  4. Run the CloudFormation template ssm-state-manager/Cfn-SSM-Ansible.yaml. You can accept the default values where provided.
    • Specify your bucket name for both the Ansible bucket and the Ansible Logs bucket.
    • Specify an EnvironmentName e.g. ssm-poc. This is used to tag resources and generate resource names that are specific to a particular environment.

The CloudFormation template spins up an ASG and configures an SSM State Manager Association for all the instances in the ASG. The association uses Ansible to configure each instance at creation time, and also regularly checks/updates each instance on a 30 minute interval.

Note that there is no need to install Ansible as part of the EC2 LaunchConfiguration UserData, as SSM automatically installs Ansible on each instance upon creation.

Set up EC2 instances to use ansible-pull

In this sample, EC2 instances in the ASG use ansible-pull to fetch the intial Ansible configuration from a git repo. This configuration then includes a cron job that polls the repo for changes using ansible-pull on a cron chedule.

  1. Create a CodeCommit repo to hold your ansible config files e.g. ansible-configs
  2. Copy the file site.yml (from the ansible-pull directory) to the repo and commit.
  3. Use the CloudFormation template Cfn-Ansible-Pull.yaml to create an AutoScaling group. This includes a userdata script to pull the ansible config from the repo.