docker-compose selenium grid (w/healthcheck)

docker-compose.yml

version: "3"
services:
  hub:
    image: selenium/hub
    ports:
      - "4444:4444"
    healthcheck:
      test: ["CMD", "wget", "--spider", "http://localhost:4444/grid/api/proxy"] 
      interval: 10s
      timeout: 5s
      retries: 3
  firefox:
    image: selenium/node-firefox
    depends_on:
      - hub
    environment:
      HUB_PORT_4444_TCP_ADDR: hub
      HUB_PORT_4444_TCP_PORT: 4444
    healthcheck:
      test: ["CMD", "wget", "--spider", "http://localhost:5555"]
      interval: 10s
      timeout: 5s
      retries: 3
  chrome:
    image: selenium/node-chrome
    depends_on:
      - hub
    environment:
      HUB_PORT_4444_TCP_ADDR: hub
      HUB_PORT_4444_TCP_PORT: 4444
    healthcheck:
      test: ["CMD", "wget", "--spider", "http://localhost:5555"]
      interval: 10s
      timeout: 5s
      retries: 3