Improve Docker build speed

[smcalilly]

Description

It takes a long time to build a docker image, and sometimes this can lead to slow work/wasted time, or worse: context switching while waiting for a build.

So I'm wondering if we can make our builds more efficient. My hunch is that DataMaders have asked this question before, so I'll start by digging in how to issues etc for any context.

Some bits of reference for me:

• https://pythonspeed.com/articles/multi-stage-docker-python/
• https://pythonspeed.com/articles/smaller-python-docker-images/

[smcalilly]

• related to #153 ?

[smcalilly]

Closing! We have

• 104