browsers.json

{
    "firefox": {
        "default": "57.0",
        "versions": {
            "57.0": {
                "image": "selenoid/firefox:88.0",
                "port": "4444",
                "path": "/wd/hub"
            }
        }
    }
}

selenoid-docker-compose.yml

version: '3'
services:
  selenoid:
    image: "aerokube/selenoid"
    network_mode: bridge
    ports:
      - "4444:4444"
    volumes:
      - "$PWD:/etc/selenoid/" # assumed current dir contains browsers.json
      - "/var/run/docker.sock:/var/run/docker.sock"
  selenoid-ui:
    image: "aerokube/selenoid-ui"
    network_mode: bridge
    links:
      - selenoid
    ports:
      - "8080:8080"
    command: ["--selenoid-uri", "http://selenoid:4444"]