The key seems to be placed in the expected location
It's an Amazon Linux AMI with the AWS CLI pre-installed on it. It uses the AWS CLI to fetch the key from AWS SSM Parameter Store. It's granted read access to that SSM Parameter via the instance role.
Let's see. The screenshots above are me running on the host, not attaching to a running container. So I believe I do want the keys to be mounted into the running containers.
Wow, it really does not want to show the output of those print statements in stdout. Here's the output of the task from the console after cloning it. Confirmed that the setup script and all code changes are present: