Simian Army Terraform

This contains a Terraform module to bring up an EC2 instance running Netflix's Simian Army, their first implementation of chaos monkey and some sample code.

simian-army module

The module brings up an EC2 instance running a Simian Army docker image. Most configuration properties in the image are exposed through terraform module variables with the same default values. You can refer to these properties here. The naming should be adapted by converting / to _ and dropping the redundant simianarmy prefix, whereas a property listed as "/simianarmy/client/aws/accountkey" become "client_aws_accountkey".

Also keep in mind that properties with boolean values should not use unquoted true and false keywords in terraform as those get converted to "0" and "1" and the image needs the actual words "true" and "false" as strings.

Sample ASG

This just brings up an AWS Auto Scaling Group that manages 1 instance running yocto-httpd in order for the monkey to have something to attack and so we're able to see it in action.

Using it on your own infrastructure

In order to make use of the Simian Army module, you only need to copy the ./modules/simian-army folder to where you keep your own Terraform modules. Then on your main.tf or whatever other .tf file you find appropriate, use the module like this:

module "simian_army" {
  name_prefix = "<optional name prefix that will be appended to the instance name>"
  source = "./modules/simian-army" # adapt this if you're using a different folder
  ami_id = "<AMI you would like to use for your simian army instace>"
  sshkeyname = "<SSH key so you can log into your simian army box and have a look inside>"
  subnet_id = "<ID of the subnet for your simian army instance>"
  vpc_id = "<ID of the VPC for your simian army instance>"

  # Configure your chaos monkey with your preferred values.
  chaos_leashed = "false"
  chaos_asg_enabled = "true"
  scheduler_frequency = "1"
  scheduler_frequencyunit = "HOUR"
  chaos_asg_probability = "1.0"
}

Interacting With Your Simian Army Instance

The public ip of the instance is exposed through a terraform output from the module as public_ip and then again through the example code as simian_army_public_ip. So when running this example you can run

terraform output simian_army_public_ip

to get the public ip of the instance. You can use this in your commands so you don't need to worry about the actual ip, for example:

• SSH into the instance

  ssh -i <path to your key> ec2-user@$(terraform output simian_army_public_ip)
  

• Make Rest API calls

  curl "http://$(terraform output simian_army_public_ip):8080/simianarmy/api/v1/chaos"