[Bug]: Environment API can not load .env files into ESM output in dev mode

[sibbng]

Version

System:
    OS: Windows 10 10.0.19042
    CPU: (4) x64 Intel(R) Core(TM) i5-7400 CPU @ 3.00GHz
    Memory: 1.94 GB / 7.83 GB
  Browsers:
    Edge: Spartan (44.19041.423.0), Chromium (127.0.2651.74)
    Internet Explorer: 11.0.19041.1
  npmPackages:
    @rsbuild/core: 1.0.1-beta.16 => 1.0.1-beta.16

Details

I use Rsbuild environment API to build a client and a server. I enforce ESM output on both environments and have module: "module" in my package.json. But Rspack trying to execute that file in CJS environment, because it requires mjs extension.

https://github.com/web-infra-dev/rspack/blob/d9a6d592e5b9cde55391a0e22786817d3bc5b63d/packages/rspack-test-tools/src/runner/runner/esm.ts#L23-L26

I fixed this issue by modifying output filename:

https://github.com/sibbng/voby-ssr-demo/blob/02d98800b11cb0306d8dc6ccb1924903f90ecac0/apps/web/rsbuild.config.ts#L75-L77

After these changes I managed to run my server in ESM mode I've got this error:

queueMicrotask undefined

I assume this is something related to vmContext. I fixed this issue by manually patching queueMicrotask for the dependencies failing. I probably should have done that in my entry files as it will be needed in the future for other deps.

https://github.com/sibbng/voby-ssr-demo/blob/02d98800b11cb0306d8dc6ccb1924903f90ecac0/packages/voby-unplugin/src/index.ts#L189

After pathing all these, I managed to get a working dev and prod environment. But for some reason, environment values are not loaded in dev mode.

https://github.com/sibbng/voby-ssr-demo/blob/02d98800b11cb0306d8dc6ccb1924903f90ecac0/apps/web/package.json#L7-L8

Even though commands are identical (except entry files), server/index.tsx missing PUBLIC environment variables defined in .env.development and throw process undefined error.

As a workaround, I manually load environment variables during to ssr environment:

https://github.com/sibbng/voby-ssr-demo/blob/9dba96c8d2de3425e11dfbcf707821a7df1605e4/apps/web/rsbuild.config.ts#L67-L72

Reproduce link

https://github.com/sibbng/voby-ssr-demo

Reproduce Steps

1. remove my workaround
2. pnpm dev
3. Visit localhost:3000 in browser
4. Check console. It says process not defined.

[9aoy]

@sibbng Thank you for providing such a detailed description of the problem.
Automatic load env is a capability provided by the Rsbuild CLI, activated when you execute the rsbuild dev / rsbuild build .
When utilizing the Environment API, you need explicitly invoke the loadEnv method. Apologies for the oversight in our documentation; I will ensure it is updated accordingly.

[sibbng]

Thanks for clarification. I will raise another issue on Rspack repo about queueMicrotask being undefined in ESM environment.