Hello.

I’m working on a Ruby on Rails project where we use GitHub actions as a CI. While adding browser tests, I face issue accessing our app from within a service container.

Here is the part of workflow file that performs browser tests:

system:
  runs-on: ubuntu-latest
  services:
    firefox:
      image: selenium/standalone-firefox:4.0
      ports: ["4444:4444"]
env:

HUB_URL: "http://localhost:4444/wd/hub"

APP_HOST: "http://localhost:4000"
steps:

- name: Checkout code

uses: actions/checkout@v2.3.1
- name: Install Ruby
  uses: ruby/setup-ruby@v1

- name: Install gems
  run: "bundle install"

- name: RUN TESTS
  run: "bundle exec rails spec:system"

Notice the APP_HOST variable. It’s used to point where the browser should connect to. My guess (I couldn’t find any information about this though) the hostname should be localhost.

These steps launch a container with Firefox, which should open our app accessible on the runner machine port 4000. But it didn’t happen: Firefox throws an error saying “http://localhost:4000 is not reachable”.

Could you please tell me are the runner machine ports blocked, or I should use some different hostname.