How to use multiple runtimes for serverless functions WITHOUT breaking local dev

[slimshreydy]

Description

I'm interested in including a mix of Python + Nextjs/node-based functions in my deployed API. I've seen #6197, which suggests that I should move all the functions (JS and python) into a /api folder at the root of my project, at which point vercel will automatically deploy each function in an appropriate runtime based on its file extension.

However it seems Nextjs itself has a hardcoded assumption that api files are defined at /pages/api (or /src/pages/api). This means that while my app now works when deployed by Vercel, it breaks on local development. I tried keeping both a /pages/api and /api folder but it seems that's not recommended either.

Any idea how I can prevent local dev from breaking?

[DiggidyDev]

+1 same issue I'm running into at the moment. I want to have go runtime Vercel functions in addition to my app router API routes, but I can't have them both at the same time in local development.

Deploying to Vercel isn't an issue - they both run there, but local development doesn't allow it.

[dmarcucci]

How do you run your project locally?

I have a project with both Edge functions and Python endpoints. I run it using the vercel command (vercel dev to be exact) and not next dev. When doing this, I have no issue calling either a Edge function or Python endpoint locally.

[DiggidyDev]

I'm using vercel dev.

I got around the issue by moving my /src/app/api routes to the top-level /api folder and refactored the routes to use the @vercel/node request types instead.

For clarification, if I had /api/foo.go alongside /src/app/api/bar/route.ts, the behaviour observed was:

	GET /api/foo	GET /api/bar
vercel dev	✅	❌
next dev	❌	✅
Deployed to Vercel	✅	✅

P.S. Apologies for the late reply, only just saw this notification :^)

[dmarcucci]

Hmm. Strange because I have both Python and JS endpoints located under /api and they both work fine with vercel dev.

For the /src/app/api/bar/route.ts endpoint, you may need to do something like /api/bar.ts or api/bar/index.ts. I think I have the endpoints in the latter convention and it works no problem.