[FEATURE-REQUEST] Pre-start commands

[worksofliam]

If I run sc start /path/to/my/node/app.yaml, I would like to define 'pre start' commands that would run things like npm i or maven package so the app can be built as part of the startup service

[worksofliam]

Perhaps just reading the dockerfile for ENV and RUN commands for the environment setup?

well i can imagine just interpreting things like ENV and RUN that could be useful as part of this startup process