Dynamic Public Environment Variables are undefined in +server.ts endpoints

[ssbm-oro]

Describe the bug

Hello, I want to start off by thanking everyone involved for their hard work and clever ideas that have brought Svelte and Sveltekit to the points that the projects are at now 🥰

I updated to the latest version of Sveltekit today, and after going through all the migrations and fixing everything, I have one remaining problem in my project, that dynamic public environment variables are not available in +server.ts endpoints.

I made a simple example repository showing the issue. After you install and build it, you can see that the public dynamic is rendered correctly when you navigate to /

If you navigate to /static, the endpoint will return a public and a private static environment variable and display 'working foo'.

If you navigate to /dynamic, the endpoint will return a public and private dynamic environment variable, and should display 'working bar'. However, the public dynamic variable is undefined, so it displays 'undefined bar'.

Reproduction

https://github.com/ssbm-oro/sveltekit-dynamic-public-bug

Logs

No response

System Info

System:
    OS: macOS 12.5
    CPU: (8) arm64 Apple M2
    Memory: 78.63 MB / 24.00 GB
    Shell: 5.8.1 - /bin/zsh
  Binaries:
    Node: 18.6.0 - /opt/homebrew/bin/node
    npm: 8.13.2 - /opt/homebrew/bin/npm
  Browsers:
    Firefox: 103.0.1
    Safari: 15.6
  npmPackages:
    @sveltejs/adapter-auto: next => 1.0.0-next.64 
    @sveltejs/kit: next => 1.0.0-next.411 
    svelte: ^3.44.0 => 3.49.0 
    vite: ^3.0.0 => 3.0.8

Severity

annoyance

Additional Information

No response

[Rich-Harris]

Braindumping my investigation so far: this is happening because vite.ssrLoadModule is loading two instances of both $env/dynamic/private and $env/dynamic/public. One is loaded by the plugin itself, in order to call the internal set_public_env and set_private_env functions before the app starts, and a second instance is loaded by the module that imports it. That second instance has env = {}, because its exported set_[mode]_env function is never called.

In theory they should be resolved to the same place, and Vite should just re-use the existing module. For some reason (possibly a bug in Vite? not 100% sure) that's not happening.

Due to a quirk in the module resolution algorithm, this doesn't happen inside the sveltejs/kit repo, only in apps that have the @sveltejs/kit package installed inside node_modules.

[bluwy]

In theory they should be resolved to the same place, and Vite should just re-use the existing module. For some reason (possibly a bug in Vite? not 100% sure) that's not happening.

I don't quite understand this part. Are we importing the modules with two different URLs that should ideally be deduped to one single instance? I can't find how this is happening in the codebase, maybe I'm missing something.

[aloker]

#5955 does not fix this issue on Windows. Here are my findings:

next.405

• $env/dynamic/public and $env/dynamic/private work as expected

next.408

• both env-objects in $env/dynamic/public and $env/dynamic/private are empty on the server side, $env/dynamic/public work on the client side

next.418

• fixes the issues for SSR on Linux, but not on Windows

next.427

• Still broken for Windows