Improve container build time in Getting Started document.

[eengelking]

Updated the Dockerfile section to improve load time from ~7s to ~2s each time a change is made to code.

[cjellick]

@iwilltry42 can you test this and approve if it works?

[iwilltry42]

Hey @eengelking , thanks for this optimization!
It makes total sense the way the layering works, so that requirements don't have to be installed everytime something in the code is changed 👍
In my tests, subsequent builds went from 8.7s to 3.2s for the whole acorn build . process.
In the getting-started guide we also use the dev mode, which works around this for development by live-reloading code with Flask :)

[iwilltry42]

LGTM

[eengelking]

In the getting-started guide we also use the dev mode, which works around this for development by live-reloading code with Flask :)

@iwilltry42 In this usecase, I was using the --dev or -i flags, but I was updating the Acornfile welcome argument instead of the Python code directly. As a result, it doesn't allow the Flask live reload to be taken into consideration.

Thank you for the approval. 👍

[cjellick]

Thanks @eengelking!