ChromeHeadless fails inside pipeline but not locally - docker

Question

I have an angular app that is using karma for tests. I am also using gitlab-ci to automate building and deploying the app.
Recently we wanted to add tests to the pipeline, using our own image with chrome.
Running it in the pipeline produces an error related to not being able to connect to the chrome process:
31 12 2018 10:58:36.116:INFO [karma]: Karma v1.7.1 server started at http://0.0.0.0:9877/
31 12 2018 10:58:36.121:INFO [launcher]: Launching browser ChromeKarma with unlimited concurrency
31 12 2018 10:58:36.134:INFO [launcher]: Starting browser ChromeHeadless
31 12 2018 10:59:36.146:WARN [launcher]: ChromeHeadless have not captured in 60000 ms, killing.
31 12 2018 10:59:36.163:INFO [launcher]: Trying to start ChromeHeadless again (1/2).
31 12 2018 11:00:36.223:WARN [launcher]: ChromeHeadless have not captured in 60000 ms, killing.
31 12 2018 11:00:36.236:INFO [launcher]: Trying to start ChromeHeadless again (2/2).
31 12 2018 11:01:36.296:WARN [launcher]: ChromeHeadless have not captured in 60000 ms, killing.
31 12 2018 11:01:36.310:ERROR [launcher]: ChromeHeadless failed 2 times (timeout). Giving up.
Running the same commands in the same docker image locally ( starting a container with the same image same commands ), I do not get the same error, and the tests run fine.
After some searches I tried adding other flags besides --no-sandbox. This is my current browser configuration:
customLaunchers: {
ChromeKarma: {
base: 'ChromeHeadless',
// We must disable the Chrome sandbox when running Chrome inside Docker (Chrome's sandbox needs
// more permissions than Docker allows by default)
flags: [
'--disable-web-security',
'--disable-gpu',
'--no-sandbox',
'--remote-debugging-port=9222'
]
}
},
I've also tried adding a sleep to the list of commands in the pipeline, and then connecting to the container and running the tests manually. This does not produce the error, and the tests run fine.
Docker version is: Docker version 17.05.0-ce, build 89658be
I should also mention that while inside the container, I ran a ps ax and saw the chrome processes starting and staying up until karma killed them.

Answer 1

Solved this issues myself. Inside our network we use a proxy for accessing the internet. Turns out that this stops chrome from connecting to karma web server. I had to unset the proxy to get it to work. Another way to resolve this, without having to remove the proxy would be adding the following flags to karma.
'--proxy-bypass-list=*',
'--proxy-server=\'http://<my org proxy server>:8080\''