How to better expose FastAPI internals for downstream modifications?

[gadomski]

As discussed in the stac-utils working group meeting on 26 June, 2023, it can be hard to customize the actual FastAPI data structure underneath our application. @lossyrob mentioned that he hasn't seen anyone do this really well -- each project allows folks to customize routes in their own way, and no one seems to make it really easy. Are there examples of FastAPI-based applications that demonstrate a good (or at least better) structure for allowing FastAPI customizations for an install? If so, we should link them into this issue, and then use them as a basis for a (v3?) refactor.

cc @constantinius @sharkinsspatial

[vincentsarago]

what kinda of customization are we talking about?

As an example, in tipg we are using something we call Endpoint Factory (which in reality is more a Router factory where we register endpoints). The Factory have couple attributes user can change (prefix, collection dependency, templates, ...).

In TiTiler we do the same thing but with much more attributed (to control almost all endpoint dependencies) and it became a mess... but it's enable a lot of customization 🤷