How Do I Test A New External DNS Provider

Here’s my docker-compose.yml file:

version: '2'

services:
    external-dns:
        image: registry.twilley.org/mathuin/external-dns
        command: -provider digitalocean
        labels:
            io.rancher.container.agent.role: environment
            io.rancher.container.create_agent: 'true'
            io.rancher.container.pull_image: always
        environment:
            - DO_PAT=secret
            - ROOT_DOMAIN=example.org