Selenium routing with subdomains

Question

I have created a docker compose file for doing Capybara tests inside a container. The problem i'm currently facing to is that i can't find a ability to to route the subdomains of my lvh.me domain. When I add lvh.me to the hosts file of Selenium I get the same result that my tests are failing. In which way can I add some routing for subdomains to Selenium to accept subdomains like {{user}}.lvh.me:3001

My Capybara configuration

Capybara.register_driver :selenium do |app|
  Capybara.app_host = "http://0.0.0.0:3001"
  Capybara.server_host = '0.0.0.0'
  Capybara.server_port = '3001'
  Capybara.always_include_port = true

  args = ['--no-default-browser-check', '--headless', '--start-maximized']
  caps = Selenium::WebDriver::Remote::Capabilities.chrome("chromeOptions" => {"args" => args})

  Capybara::Selenium::Driver.new(
      app,
      browser: :remote,
      url: "http://hub:4444/wd/hub",
      desired_capabilities: caps
    )
end

Capybara.configure do |config|
  config.default_driver = :rack_test
  config.javascript_driver = :selenium
end

And my docker compose file

version: '3'
services:
  db:
    image: postgres
    volumes:
    - ./tmp/db:/var/lib/postgresql/data
  redis:
    image: redis
    volumes:
    - ./tmp/redis:/var/lib/redis/data
  web:
    build: .
    environment:
    - REDIS_URL=redis://redis
    - DATABASE_HOST=db
    command: sh "/myapp/docker-entrypoint.sh"
    volumes:
    - .:/myapp
    links:
    - db
    - redis
    - hub
    depends_on:
    - db
    - redis
    ports:
      - "3001:3001"
      - "3000:3000"
  hub:
    container_name: hub
    image: selenium/hub:3.9
    ports:
    - "4444:4444"
  selenium:
    container_name: selenium
    image: selenium/node-chrome:3.9
    environment:
      HUB_PORT_4444_TCP_ADDR: hub
      HUB_PORT_4444_TCP_PORT: 4444
    depends_on:
      - hub
    links:
      - hub

Answer 1

Firstly you shouldn't be specifying the Capybara config inside the driver registration. Secondly, this is going to assume you're running your tests on the web docker instance -- if you're actually trying to run your tests on the host then things would be slightly different.

Capybara.app_host needs to be set to a URL that points to where the app under test is running from the perspective of the browser. In your case the browser is running on the selenium docker instance, and the tests should start the AUT on the web instance - that would mean Capybara.app_host should be http://web (port is not needed since you've specified alway_include_port). That means you should end up with

Capybara.register_driver :selenium do |app|
  args = ['--no-default-browser-check', '--headless', '--start-maximized']
  caps = Selenium::WebDriver::Remote::Capabilities.chrome("chromeOptions" => {"args" => args})

  Capybara::Selenium::Driver.new(
    app,
    browser: :remote,
    url: "http://hub:4444/wd/hub",
    desired_capabilities: caps
  )
end

Capybara.configure do |config|
  config.app_host = "http://web"
  config.server_host = '0.0.0.0'
  config.server_port = '3001'
  config.always_include_port = true

  config.default_driver = :rack_test
  config.javascript_driver = :selenium
end

Your next issue it you want to use which lvh.me which resolves to 127.0.0.1 but you need it to resolve to whatever ip is assigned to the web docker instance. If you have a fixed number of subdomains used in your tests you should be able to handle that via link aliases specified in the selenium docker instance config - https://docs.docker.com/compose/compose-file/#links - or via network aliases if you specify networks in your docker compose config - https://docs.docker.com/compose/compose-file/#aliases. If you do actually need to resolve wildcard (*.lvh.me) then you'll need to run your own DNS server (possibly in your docker setup) with a wildcard CNAME entry that resolves *.lvh.me to web