If you use Cloudformation with Powershell – and I do – you’ve probably run into this error message more than once.
If you’re like me, you’ll have tried to suppress it in several ways. You’ve tried to check your own template for changes, avoiding the call if there are none. And you’ve probably fallen foul of tiny, insignificant differences that CloudFormation doesn’t care about. You’ve probably done the same with your parameters and hit similar problems.
You might even have taken to adding a timestamp to a harmless field of your template so that at least something has updated. At an unnamed previous company, we’d just add a comment to the end of a launchconfiguration’s powershell script, which was enough to force an update and suppress the error. You might even be fine with just ignoring the rain of red text.
In my current project, we can’t just ignore it, as we’re driving our templates out of Octopus Deploy. “No updates are to be performed” throws and aborts our pipeline, which is annoying. But we want to catch other, genuine error messages from Update-CfnStack.
So what to do?
Well, turns out this is an object lesson in correct use of try/catch.