Docker Secrets ASP.NET Core

Question

I want to access Docker Secrets in my ASP.Net Core project.

I distilled the issue down to a test API project. All it does is read the directories inside /run/

[HttpGet]
public IEnumerable<string> Get()
{
  return Directory.GetDirectories("/run");
}

I changed the compose files to 3.1 and added the plumbing for secrets listed here: how do you manage secret values with docker-compose v3.1?

version: '3.1'

services:
  secrettest:
    image: secrettest
    build:
      context: ./SecretTest
      dockerfile: Dockerfile
    secrets:                    # secrets block only for 'web' service
     - my_external_secret

secrets:                        # top level secrets block
  my_external_secret:
    external: true

The get action returns ["/run/lock"]. I do not see a /run/secrets directory. I also shelled into the container to verify it does not see the /run/secrets directory.

I am able to see secrets from other containers. Anyone know what I am missing? Is there another strategy I should take other than the 3.1 compose to configure the container in VS 2017?