AWS::CloudFormation::Init not executing commands

You have to execute cfn-init in order for AWS::CloudFormation::Init to do anything. This is most commonly done via cloud-init user data. Here is the example from the cfn-init documentation:

UserData: !Base64 
  'Fn::Join':
    - ''
    - - |
        #!/bin/bash -xe
      - |
        # Install the files and packages from the metadata
      - '/opt/aws/bin/cfn-init -v '
      - '         --stack '
      - !Ref 'AWS::StackName'
      - '         --resource WebServerInstance '
      - '         --configsets InstallAndRun '
      - '         --region '
      - !Ref 'AWS::Region'
      - |+