Run rover supergraph compose on Alpine

[EverlastingBugstopper]

Currently, when building Rover for Alpine Linux, we disable the rover supergraph compose command. This is because the underlying composition function is written in JavaScript, and we use rusty_v8 under the hood to execute this function. Unfortunately, rusty_v8 is only built to dynamically link against glibc >= 2.18, which is incompatible with Alpine as it requires all binaries to be statically linked and built with musl-libc.

We want to support running all Rover commands on Alpine, this issue is meant to track discussion about possible paths towards that future.

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• Bundle the JavaScript file that does composition with the musl build, and shell out to node directly to run composition
  • This one is kinda rough but might be the easiest option. The idea is that you'd require node to be installed as a runtime dependency.
  • Installing node on Alpine can be a bit of a hassle (though there are images for it)
• Create a cloud function that executes composition and use that with the musl build
  • If we do this, we may want to add a --cloud flag to rover supergraph compose on other builds so anybody can run the same composition algorithm that the Apollo Graph Registry runs
• Wait for rusty_v8 to build binaries for musl
  • We aren't sure how long this will take, but this would be by far the easiest option for us
• Write a composition function in pure Rust
  • This is a big lift and won't be possible until we've made significant investments into the Rust GraphQL ecosystem