explore using the `tool` section in Spin manifest to automate bindings

[karthik2804]

We should explore using the tool section in the Spin manifest to contain details about the language and the source language and develop a way to generate the required bindings.

[itowlson]

The 98%¹ case is that you can guess the source language by looking at the source - that was what I did in the shenanigans branch². I'm on board with tool annotations in the manifest but I'd favour not requiring them in cases where we can infer correctly!

Footnotes

1. I obtained this number by SCIENCE and definitely not by MAKING IT UP ↩

2. https://github.com/itowlson/spin-deps-plugin/blob/4449ead1e4ec34dd6ff5dd2777df123c578b7cb9/src/commands/add.rs#L372 ↩

[karthik2804]

Is there a preference to do the inference when we can easily specify them in the tools section on a template to have a 100% hit rate? This is more of a curiosity question.

The goal with this issue was to be able to not be required to run the bindings step manually and also lay foundation to automate more things by using the config section. I am totally happy if we do inference as a fallback to not having the config section in the manifest.

[itowlson]

It somewhat depends how the language entry gets added, but I actually think inference is more reliable than a user-controlled section, because the build section and the code on disk are authoritative. If the build command says cargo then I know it's gonna need Rust bindings; if it says npm then it's gonna need JS bindings. If the user says "it's Rust," well, they're probably right, but maybe they copied and pasted the wrong thing, or had a brain fart thinking about something else while typing, and now they have to go mop up all the garbage we generated into their JS project. Rare? Yes. But so will inference failures be. And almost all inference failures will be more obvious and less confusing (because we will fail to infer rather than inferring the wrong thing).

I agree though that this is a detail, and agree with the overall goal (that was, indeed, exactly what the shenanigans branch was exploring). spin deps add and it all just works, however we get there!

[karthik2804]

That makes sense. I appreciate the detailed explanation!