Fixing Docker build issues. Updated chrome, Potentially fixing issues #603 #537.

[iain17]

I wanted to use Chrome and the latest version of BackstopJS using Docker. However the automatic build of BackstopJS isn't working.

This PR fixes the docker build error and updates PhantomJS and Chrome. In order to run on the latest stable Chrome 64 build, I had to change the original alpine base image to the default node image. This potentially fixies the memory leak issues reported in #603 #537

You can test it out on: https://hub.docker.com/r/iain17/backstopjs/

[garris]

Many thanks!

[lmakarov]

The switch to the default (non-alpine) flavor of the base nodejs docker image inflated the resulting (compressed) image size from 303 MB to 653 MB - http://take.ms/9XvDE

Looks like Alpine Edge now has Chromium v64 available:
https://pkgs.alpinelinux.org/package/edge/community/x86_64/chromium

For a smaller image size either alpine or the slim flavor of the node image should be used.
See https://hub.docker.com/r/library/node/tags/

• 8 - Compressed size: 270 MB
• 8-slim - Compressed size: 92 MB
• 8-alpine - Compressed size: 23 MB

[garris]

Hi @lmakarov! Would you mind PR-ing?

[lmakarov]

Hey @garris! I believe rolling back to Alpine would be the easiest. I do, however, like how much simpler the Dockerfile is with Debian. Alpine is the goto distribution for Docker images, however it does make things more complex, as weird workarounds have to be used quite often.

Using 8-slim (a stripped down version of Debian) may be a good middle ground so long as it actually works without introducing workarounds of its own.

@iain17 would you be interested in trying 8-slim as the base image? If not, I'll try to find some time this week for that.