anchor.diff:  
   We have built a [CloudFormation template](https://github.com/buildkite/elastic-mac-for-aws)
   that configures an Auto Scaling group, Launch Template, and Host Resource Group
  -suitable for maintaining a pool of EC2 mac1.metal instance based Buildkite
  +suitable for maintaining a pool of EC2 `mac1.metal` instance based Buildkite
   Agents. These agents can be used to run Buildkite Pipelines that build Xcode
   based software projects for macOS, iOS, iPadOS, tvOS, and watchOS.
   
   As you must prepare and supply your own AMI for this template, macOS support has
   **not** been incorporated into the Elastic CI Stack for AWS.
   
  -Using an Auto Scaling Group for your instances ensures booting your macOS
  +Using an Auto Scaling group for your instances ensures booting your macOS
   Buildkite Agents is repeatable, and provides automatic instance replacement when
   hardware failures occur.
   
  
positive.code: 
  ## Starting your Buildkite Agents
  
  Once you have successfully deployed the template, use the template Resources tab
  to find the Auto Scaling Group. Edit the Auto Scaling Group and set the Desired
  Capacity to the number of instances you require.
  
  The Auto Scaling Group will automatically provision Dedicated Hosts using the
  Host Resource Group and boot instances on them. The Launch Template’s `UserData`
  script will install, configure, and start the Buildkite Agent.
  
  Caveat the use of dynamic scaling policies on the Auto Scaling Group, instances
  are slow to boot and slow to terminate. Consider using Scheduled Scaling Rules.
  
  ## F.A.Q.
  
  ### My ASG doesn’t launch any instances
  
  
negative.code: 1. Configure instance VPC subnets, security groups, and key pairs so that you
  can access the instance.
  1. Using an SSH or SSM session:
  	* Set a password for the ec2-user using `sudo passwd ec2-user`
  	* Enable screen sharing using `sudo /System/Library/CoreServices/RemoteManagement/ARDAgent.app/Contents/Resources/kickstart -activate -configure -access -on -restart -agent -privs -all`
  1. Using a VNC session:
  	1. Sign in as the `ec2-user`
  	1. Enable Automatic login for the ec2-user in System Preferences > Users & Accounts > Login Options
  	1. Disable Require password in System Preferences > Security & Privacy > General
  1. Install your required version of Xcode, and ensure you launch Xcode at least
  once so you are presented with the EULA prompt.
  1. Using the AWS EC2 Console, create an AMI from your instance.
  
  You do not need to install the `buildkite-agent`, it is automatically installed
  by the Launch Template `UserData` script.
  
  ## Associate your AMI with a Customer managed license in AWS License Manager
  
  To launch an instances using a Host Resource Group, the instance AMI must be
  associated with a Customer managed license in *AWS License Manager*.
  
  Using the AWS Console, open the *AWS License Manager* and navigate to
  *Customer managed licenses*. Create a new Customer managed license, enter a
  descriptive name and select a License Type of `Cores`.
  
  Once your Customer managed license has been saved, open the detail view for your
  license. Open the *Associated AMIs* tab and choose *Associate AMI*. From the
  list of *Available AMIs*, select your macOS AMIs and then click *Associate*.
  
  ## Deploy the CloudFormation template
  
  Using the VPC and AMI prepared earlier, prepare values for the following
  required parameters:
  
  * `ImageId` from your AMI set up
  * `RootVolumeSize`
  * `Subnets` from your VPC set up
  * `SecurityGroupIds` from your VPC set up
  * `IamInstanceProfile` if accessing AWS services from your builds, provide an Instance Profile ARN with an appropriate IAM role attached
  * `BuildkiteAgentToken` an Agent Token for your [Buildkite Organization](http://buildkite.com/organizations/-/agents)
  * `BuildkiteAgentQueue` the Buildkite Queue your Pipeline Steps target
  
  There are also optional parameters to configure the size of the Auto Scaling
  Group:
  
  * `MinSize` defaults to 0
  * `MaxSize` defaults to 3
  
  The default AWS Limit for `mac1.metal` is 3 dedicated hosts per account region. If
  you require more than 3 instances, request an increased limit in the *AWS
  Service Quotas Dashboard*.
  
  ### Deploy Using the AWS Console
  
  Use the launch button below to Create a CloudFormation stack from the latest
  version of our template:
  
  <a href="https://console.aws.amazon.com/cloudformation/home#/stacks/new?stackName=buildkite-mac&templateURL=https://s3.amazonaws.com/buildkite-serverless-apps-us-east-1/elastic-mac/template/latest.yml"><%= image "launch-stack.svg", alt: "Launch stack button" %></a>
  
  Ensure the selected region in the top menu bar matches the region of your VPC
  and AMI resources.
  
  Give your stack a unique name, and fill in the required parameters.
  
  ### Deploy Using the AWS CLI
  
  To deploy using the AWS CLI, save your parameters in a `.parameters.json` file
  and run the following commands:
  