clicker: problem testing e2e in docker image

Hi, I have problems running the e2e tests in the following docker image: https://gist.github.com/geoHeil/48cd94bf4d748fd8fd6d25de4c272157

Chrome seems to be unreachable, even though chromium is installed:

WebDriverError: chrome not reachable
  (Driver info: chromedriver=2.21.371461 (633e689b520b25f3e264a2ede6b74ccc23cb636a),platform=Linux 4.4.14-moby x86_64)
    at WebDriverError (/home/jenkins/clicker/node_modules/protractor/node_modules/selenium-webdriver/error.js:27:10)
    at Object.checkLegacyResponse (/home/jenkins/clicker/node_modules/protractor/node_modules/selenium-webdriver/error.js:580:13)
    at /home/jenkins/clicker/node_modules/protractor/node_modules/selenium-webdriver/lib/webdriver.js:64:13
    at Promise.invokeCallback_ (/home/jenkins/clicker/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:1329:14)
    at TaskQueue.execute_ (/home/jenkins/clicker/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2790:14)
    at TaskQueue.executeNext_ (/home/jenkins/clicker/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2773:21)
    at /home/jenkins/clicker/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:2652:27
    at /home/jenkins/clicker/node_modules/protractor/node_modules/selenium-webdriver/lib/promise.js:639:7
    at process._tickCallback (node.js:369:9)
From: Task: WebDriver.createSession()
    at acquireSession (/home/jenkins/clicker/node_modules/protractor/node_modules/selenium-webdriver/lib/webdriver.js:62:22)
    at Function.createSession (/home/jenkins/clicker/node_modules/protractor/node_modules/selenium-webdriver/lib/webdriver.js:295:12)
    at Driver (/home/jenkins/clicker/node_modules/protractor/node_modules/selenium-webdriver/chrome.js:778:38)
    at Direct.getNewDriver (/home/jenkins/clicker/node_modules/protractor/built/driverProviders/direct.js:65:26)
    at Runner.createBrowser (/home/jenkins/clicker/node_modules/protractor/built/runner.js:182:43)
    at /home/jenkins/clicker/node_modules/protractor/built/runner.js:255:30
    at _fulfilled (/home/jenkins/clicker/node_modules/protractor/node_modules/q/q.js:834:54)
    at self.promiseDispatch.done (/home/jenkins/clicker/node_modules/protractor/node_modules/q/q.js:863:30)
    at Promise.promise.promiseDispatch (/home/jenkins/clicker/node_modules/protractor/node_modules/q/q.js:796:13)
    at /home/jenkins/clicker/node_modules/protractor/node_modules/q/q.js:556:49