Beanstalk on Windows: How do I prevent commands running on re-deployment?

Question

I'm trying to take advantage of AWS Elastic Beanstalk's facility to customize the EC2 instances it creates. This requires creating a .config file in the .ebextensions directory.

You can specify a number of commands which should be executed when the application is deployed to an instance. I'm using that to install some msi files, and also to configure EC2 to assign the instance a unique name. This then requires a reboot.

My problem is that I only want these commands to be run when an instance is first deployed. When I deploy a code-only change to existing instances they shouldn't be run.

I've tried using the "test" parameter, which should prevent the command running. I create a file as the last command, and then I check for the presence of that file in the "test" parameter. But it doesn't seem to work.

My config file is like this:

# File structure documented at http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/customize-containers-windows-ec2.html
files:
  "C:\\Users\\Public\\EnableEc2SetComputerName.ps1":
    source: "[File Source]"
commands:
  init-01-ec2setcomputername-enable:
    test: cmd /c "if exist C:\\Users\\Public\\initialised (exit 1) else (exit 0)"
    command: powershell.exe -ExecutionPolicy Bypass -File "C:\\Users\\Public\\EnableEc2SetComputerName.ps1"
    waitAfterCompletion: 0
  init-05-reboot-instance:
    test: cmd /c "if exist C:\\Users\\Public\\initialised (exit 1) else (exit 0)"
    command: shutdown -r # restart to enable EC2 to set the computer name
    waitAfterCompletion: forever
  init-06-mark-initialised:
    test: cmd /c "if exist C:\\Users\\Public\\initialised (exit 1) else (exit 0)"
    command: echo initialised > C:\\Users\\Public\\initialised
    waitAfterCompletion: 0

Is there an alternative way to accomplish this? Or am I doing something stupid?

On Unix-based systems, there are the touch and test commands (referred to in this answer asking the equivalent question for Unix systems). What's the equivalent in Windows which will work best in this situation?

Answer 1

I think the problem lies in the fact that you are rebooting the machine before you can write the initialized file. You should be able use a bat file which first writes the semaphore, then reboots the instance, and run that .bat file contingently on the existence of semaphore.

You can either download the .bat file with a files:source: directive or compose it in the .config with a files:content: directive.

Otherwise, your test: lines look good (I tested them locally, without a reboot).