Chrome not captured when using karma with Docker

I am trying to run some karma tests using chrome in a Docker container. My Dockerfile looks like:

FROM node:6-alpine

RUN apk update \
  && apk add --update alpine-sdk \
  && apk add chromium \
  && npm install -g @angular/cli@1.0.0 \
  && ng set --global packageManager=yarn \
  && apk del alpine-sdk \
  && rm -rf /tmp/* /var/cache/apk/* *.tar.gz ~/.npm \
  && npm cache clear \
  && sed -i -e "s/bin\/ash/bin\/sh/" /etc/passwd

  ENV CHROME_BIN=/usr/local/bin/my-chrome-build

When I run ng test in this container (having mounted a project which I know works), I get:

$ ng test -sr && yarn run test:server
04 04 2017 10:32:27.896:INFO [karma]: Karma v1.5.0 server started at http://0.0.0.0:9876/
04 04 2017 10:32:27.915:INFO [launcher]: Launching browser Chrome with unlimited concurrency
04 04 2017 10:32:27.985:INFO [launcher]: Starting browser Chrome
04 04 2017 10:33:28.047:WARN [launcher]: Chrome have not captured in 60000 ms, killing.
04 04 2017 10:33:30.053:WARN [launcher]: Chrome was not killed in 2000 ms, sending SIGKILL.
04 04 2017 10:33:32.056:WARN [launcher]: Chrome was not killed by SIGKILL in 2000 ms, continuing.
error Command failed with exit code 1.

I don't really know how to debug this, any ideas what might be wrong or how I can find out more?

from Chrome not captured when using karma with Docker