Spin Improvement Proposal: Modularizing spin.toml

[tschneidereit]

This PR adds a SIP describing changes that'd allow developers to split the spin.toml manifest up into a main application manifest and sub-manifests for individual contained components.

Signed-off-by: Till Schneidereit [email protected]

[itowlson]

I should add that I do like the implications of isolation rather than mere textual splitting. One of the challenges I ran into with the previous attempt at this (which was basically naive inclusion) was providing good locations for errors. Being able to parse and analyse sub-manifests separately, and combine them mostly-reliably only once parsed, should address that nicely. I am very keen that we think about how to give good pointers in failure cases in this work!

[seungjin]

Once I switched my app to a microservice-style structure, my spin.toml became bloated and complicated. I even considered creating my own spin.toml compiler to generate a final configuration from smaller spin.toml files at build time.

[fibonacci1729]

I'm going to start an in-parallel WIP for this SIP as it currently stands.