Feature request: Add option to upload template file to S3 bucket

[scooper91]

We want to use this action to generate a changeset for a CloudFormation stack, but the template exceeds the maximum inline file limit and errors with:

Error: Template size exceeds CloudFormation limit (51,200 bytes). Consider using a template URL from S3 instead of inline template content.

When using the AWS CLI to deploy, you can specific a bucket to upload the template to, e.g.
aws cloudformation deploy --stack-name my-stack --template-file my-template.json --s3-bucket my-deployment-bucket

Would it be possible to add this functionality (and the associated options) to this action, so we don't have to upload the template file ourselves? This would align the action more with the CLI.

Whilst the option to upload the template to a bucket is only a thing for cloudformation deploy in the CLI, it would also be useful when just creating a changeset (which is what we're trying to do).

Thanks!

[kddejong]

I was thinking about this as I worked on v2. I think this a good request. We would need to know the bucket you want us to upload too.

I'm curious what you are doing with asset management. So as a general question how do you handle other assets like Lambda functions that aren't inline? The AWS CLI has a command to package a template where it helps load local artifacts and then you do a deployment from there. This may be the next feature request but to start we could take in a bucket name and as long as the credentials have putObject on that bucket we should be able to upload it and use it.

[scooper91]

In general, we tend to use Docker images that we upload to ECR, even for things like Lambdas, as it allows us to test locally more comprehensively. If we were want to deploy a code bundle, having the ability to do that from the action would be useful, although it feels like quite a different feature to just uploading the template file.

Thanks!