Vite Plugin: generate sourcemap on build if user specified `upload_source_maps: true`

[sushichan044]

Describe the solution

Currently, even if upload_source_maps: true is specified in wrangler.json, the Vite Plugin does nothing in particular. To actually upload sourcemaps, you need to write an additional plugin and change the vite config in user land.

I propose handling this internally in the Cloudflare Vite Plugin and automatically generating sourcemaps during the build for all Worker environments.
Specifically, we will set build.sourcemap: true. I believe there are no security issues caused by the code deployed to Workers having sourceMappingURL, and wrangler deploy also sets sourceMappingURL to the end of the worker file.

I am willing to contribute to this change.

Supporting Informations

https://developers.cloudflare.com/workers/wrangler/configuration/#source-maps
https://developers.cloudflare.com/workers/vite-plugin/reference/vite-environments/

https://vite.dev/config/build-options#build-sourcemap
https://vite.dev/guide/api-environment-plugins#registering-new-environments-using-hooks
https://vite.dev/guide/api-environment#environments-configuration:~:text=The%20EnvironmentOptions%20interface%20exposes%20all%20the%20per%2Denvironment%20options.%20There%20are%20environment%20options%20that%20apply%20to%20both%20build%20and%20dev%2C%20like%20resolve.

[sushichan044]

I've put a PoC implementation at #11965.
It's currently a draft because the issue hasn't been triaged yet.

[jamesopstad]

Hi @sushichan044. Thanks for the issue. I agree that it would be nice to not need to specify both upload_source_maps in the Worker config and build.sourcemap in the Vite config. My feeling, however, is that the inference should be the other way round i.e. upload_source_maps should be inferred from build.sourcemap unless it is explicitly specified. This means that source maps will be automatically uploaded for users that build them unless they explicitly opt out by setting upload_source_maps to false. With the Vite plugin, we prefer to have build related config in the Vite config rather than the Worker config. How does that sound?

[sushichan044]

@jamesopstad Thanks for the reply! I think that sounds pretty natural and good.

My understanding is that if sourcemap settings can be configured per Vite environment, then upload_source_maps will behave as true if one or more environments are generating sourcemaps. Is this correct?

Also, I think it would be better to automatically disable sourcemap generation for the client environment internally
(I'm concerned about sourcemaps being included in Workers Assets if they are generated).