So, this is a little bonus demo because my last demo was running for far too long. It should only be a couple of minutes on a nested version of my CloudFormation web server demonstration. Let's head over to VS Code.

Okay, so we're in VS Code. I've still got my AWS profile exported. I've got my webserver-nested CloudFormation template which only has a single parameter which is the image ID for the current Ubuntu image.

Those two parameters that I had before for the VPC and subnet ID are no longer there because we're getting them from somewhere else. I've got here is a VPC stack resource which has a type of CloudFormation stack which is currently pointed in a network.yaml.

This won't work as written. For reasons known only to themselves, CloudFormation won't let me use local files for an Essence stack. That template URL has to be an S3 URL, so that's just a placeholder. Other than that, same as I had before, HTTP-only security group on EC2 instance.

I'm changing the homepage to say this is a nested stack. We're outputting the web server's public DNS name. The big difference is rather than using parameters for the subnet ID, I'm getting the output directly from that nested stack.

So, what's going to happen? CloudFormation is going to hit this resource, go and find the actual S3 URL, create that stack. Once that's completed, it will come back and do the rest of that. So, this VPC ID and public subnet will exist already.

So, now I need to do a little bit of magic to replace that with an object in S3. There's a command in CloudFormation and now there is CLI that will let me do that. It's called, that's right, this is my CFN nested demo. It's called CloudFormation package.

So, the template file is that webserver-nested. I'm telling it to push that network.yaml up into up into S3 and now I can deploy it. There's my package template with the S3 URL in it.

But now that, go ahead and create the stack, and again, we'll wait for that to create to be complete. That took a bit longer than I expected, so I actually stopped. That's why you had a transition.

Grab the public DNS name output, echo it out with an HTTP, control, and click. Yep. And there you have it. And now that I'm done, I'm going to tear down all of my stacks. Thanks for watching, hope you found it useful.

Demo: AWS CloudFormation Nested Stack

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