feat(remix-serve): allow passing getLoadContext to createApp

[TillaTheHun0]

This PR allows passing getLoadContext into @remix-run/express from @remix-run/serve. It doesn't change current functionality, just exposes getLoadContext on @remix-run/serve

The use case is that as a developer, I want to programmatically invoke createApp, to get the built express app, and then manually start the server, or even modify the app further ie. more routes, middleware, etc. Allowing to pass getLoadContext seemed kosher to me.

This of course would not be available via the remix serve CLI.

An alternative approach would be for a developer to reimplement what @remix-run/serve is doing, if they want to provide a getLoadContext. Though I would rebut that since @remix-run/serve interfaces with @remix-run/dev and wires all of the Remix build outputs into express for the developer, I think exposing here would help avoid potential "issue bloat" from folks implementing a million different ways. They could just use @mirex-run/serve.

• Docs
• Tests

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[remix-cla-bot]

Thank you for signing the Contributor License Agreement. Let's get this merged! 🥳

[kiliman]

Hmm.. it seems like if you need to use context, it would be simpler to just use the Express adapter. Remix App Server is meant to be a batteries-include no-config server.

You can eject from RAS to Express using this script: https://github.com/kiliman/rmx-cli#eject-ras

[ZipBrandon]

Is this accomplishing the same objective as #2045 and #1606 ? If so, then #2045 is the most conditioned PR to merge. Hopefully that will get merged shortly now that Remix Conf is in the rearview.

[chaance]

Echoing @kiliman's sentiments here, based on your use-case this is exactly why we have our lower-level Express adapter. remix-serve is designed to get you up-and-running, but it isn't meant to satisfy the need for load context and high levels of customization. I generally expect that most apps will ultimately end up with the need to call createRequestHandler in their own server, and it sounds like you're already there 🙂