Support for serverless functions in build/api with Github deyployments?

[stevefrench39]

TL;DR - We generate serverless functions in a build step and can't get them to work in deployments triggered by Github. Does Vercel support serverless functions contained in a /build/api folder or do they have to be in /api?

We have a Typescript API with the following file structure:

.
├── build [generated during build step]/
│   └── api/
│       └── ping
├── src/
│   └── api/
│       └── ping
└── tsconfig.json

On yarn build, src/* is transpiled to generate the serverless functions in build/api/*.

Deploying this manually is easy. In Vercel, set Project Root: build and run vercel. The serverless functions are successfully built and deployed. However, when Github attempts to automatically deploy a preview branch during a pull request, we receive the following error:

Error: The specified Root Directory "build" does not exist. Please update your Project Settings. Learn More: https://vercel.com/docs/build-step#root-directory

This is because the build directory is not committed to Github, but is generated during the build step. We tried to fix it by unsetting Root Directory and setting Output Directory: build. In this case, the deployment succeeds it does not build the serverless functions!

Other than committing our build directory to Github, we're out of ideas on how to make this seemingly common use case work. What are we missing?

[stevefrench39]

This was eventually solved by skipping the build step entirely and simply setting src as the root directory. Vercel was able to automatically detect and build the serverless functions in the src/api directory.