Unable to use --cli-input-yaml with aws cloudformation create-stack

[gautaz]

Hello,

I am trying to wrap up arguments for the command aws cloudformation create-stack in a YAML file to be then passed with --cli-input-yaml.

My current working command line is:

aws cloudformation create-stack --stack-name CfnGitSyncPrerequisites --template-body file://git-sync/prerequisites.yaml --capabilities CAPABILITY_NAMED_IAM

Hence reproducing the exact same arguments in a YAML file (git-sync-prerequisites-stack.yaml) would from my understanding be with the following content:

StackName: CfnGitSyncPrerequisites
TemplateBody: file://git-sync/prerequisites.yaml
Capabilities:
- CAPABILITY_NAMED_IAM

But when using this YAML file with --cli-input-yaml, it fails:

❯ aws cloudformation create-stack --cli-input-yaml file://git-sync-prerequisites-stack.yaml

An error occurred (ValidationError) when calling the CreateStack operation: Template format error: unsupported structure.

I have tried to compare the --debug logs of each commands but I was unable to spot the issue (apart that the content of the git-sync/prerequisites.yaml file is not displayed in the logs for the --cli-input-yaml command).

Any idea on how to debug this or make this work is welcome.