Make Dockerfile more efficient for caching and add yarn

[noeljackson]

I've updated the Dockerfile to split up package installation and removal, as well as decreasing build times, by having npm install cached separately, then copied over. This Dockerfile allows docker-compose to work more efficiently as well. I installed yarn for increased speed and also to allow development work to take place if using docker run -it for example.

[leebenson]

@noeljackson - I swapped yarn for npm's package-lock.json in a previous commit, because there were issues installing various binary packages that relied on NPM's post-install step (that, at least at the time, yarn didn't execute.)

Do you know if those legacy issues have been solved in yarn?

[noeljackson]

@leebenson Yes, these have been fixed over here: yarnpkg/yarn#800 :)

[ghost]

In my personal tests, npm 5.x is actually faster and gives better results than yarn.

[noeljackson]

My perception was that it’s useful enough to a lot of people, that you could easily include it on the Dockerfile to enable easy development with npm or yarn. If we need to rip it out, that’s fine. The most important part of the Dockerfile is the separation of operations. Caching is important.

[leebenson]

Please re-commit without yarn. That keeps consistency with the project's 'package-lock.json'

[leebenson]

@noeljackson - after inspecting this some more, one issue with your Dockerfile version is that the RUN apt-get remove --purge -y ${EPHIMERAL_PACKAGES} is moot-- by the time that command is run, the original image size has already been inflated by the packages already installed. That's why the default Dockerfile does the package bundling, installation and tear-down, as a single step.

So it solves caching, but the image is much bigger. So it's a toss-up between which is more important to your build environment.

[leebenson]

I'll play about with the Dockerfile later and attempt to optimise for caching, whilst keeping the size pretty low.

[noeljackson]

@leebenson There are some other issues as well, when using the current and the proposed Dockerfile in production, though I've fixed those. I will tinker and see what's the best I can come up with. Cheers.

[leebenson]

Thanks @noeljackson.