Local registry with localhost as url

[ghost]

Hello!
I am trying to test the docker registry manager with the simplest possible setup.
My registry is in a container and contactable at localhost:5000.

Here is the registries.yml:

registries:
  exampleRegistry:
    displayname: registry
    url: localhost
    port: 5000 # Example: 443, 8080, 5000
    #username: exampleUser
    #password: examplePassword
    refresh-rate: "5m" # Example: 60s, 5m, 1h

However, when I run docker-compose up -d, I cannot see anything at localhost:8080 on my browser.

Running docker-compose logs -f docker-registry-manager gives:

docker-registry-manager    | time="2020-12-09T13:20:33Z" level=info msg="Using registries located in /app with file name registries" file=allregistries.go line=161 source=app
docker-registry-manager    | time="2020-12-09T13:20:33Z" level=fatal msg="Failed to create registry (localhost): Invalid scheme: " file=allregistries.go line=198 source=app
docker-registry-manager exited with code 1

What is wrong here?

Best regards.