VIRTUAL_HOST_MULTIPORTS support

[poehlert]

nginx-proxy and dockergen support a convenient advanced feature for containers that may expose multiple services/ports that you want to put behind different domains. The MinIO container is a great example, which hosts the data plane and control plane as separate services on separate ports. Running multiple containers is not an option in this case as they would compete for state.

Desired outcome

Support VIRTUAL_HOST_MULTIPORTS.

Continuing with the MinIO example:

services:
  minio-container:
    image: somebodys/minio
    container_name: minio-container
    environment:
      VIRTUAL_HOST_MULTIPORTS: |-
        s3.example.com:
          "/":
            port: 9000
        minio.example.com:
          "/":
            port: 9001

Would get certificates s3.example.com,minio.example.com and make them available for the nginx config.