curl in webassembly with wss instead of ws

[rubenarslan]

Hi, @jeroen explains here how to get curl to work in webassembly. His example works in the webr REPL, but I could not figure out how to configure the default from ws to wss in quarto live. I tried

webr::eval_js('
  if (typeof Module !== "undefined" && Module.SOCKFS) {
    Module.SOCKFS.websocketArgs = Module.SOCKFS.websocketArgs || {};
    Module.SOCKFS.websocketArgs.url = "wss://";
  }
')

but SOCKFS was not defined.

[jeroen]

It should suffice to set the environment variable ALL_PROXY="socks5h://test:yolo@ws.r-universe.dev:443"

[rubenarslan]

Hi Jeroen, thanks for the prompt reaction. I tried this, but from the console it seemed as if quarto live defaults to ws://. Here's my non-working reprex:

{{< include _extensions/r-wasm/live/_knitr.qmd >}}

```{webr}
#| autorun: true
#| context: setup

# Try to trigger socket initialization first
tryCatch({
  curl::curl_fetch_memory("https://httpbin.org/get")
}, error = function(e) {
  # Expected to fail, but initializes SOCKFS
})

# Now set wss://
webr::eval_js('
  if (typeof Module !== "undefined" && Module.SOCKFS) {
    Module.SOCKFS.websocketArgs = Module.SOCKFS.websocketArgs || {};
    Module.SOCKFS.websocketArgs.url = "wss://";
  }
')

# Now configure proxy
Sys.setenv(ALL_PROXY='socks5h://test:yolo@ws.r-universe.dev:443')

# Try actual request
curl::curl_fetch_memory("https://httpbin.org/get")
```

[georgestagg]

Hi,

Since version 0.5.5 webR includes the required code changes to support curl requests, and also sets -s WEBSOCKET_URL=wss:// during its build process so that it should default to using wss://.

However, there are two issues with doing this in Quarto Live right now:

1. Quarto Live is currently still on v0.5.4 of webR, it does not have curl support yet. Luckily, upgrading should not be difficult.

2. The webR curl support only works when using the SharedArrayBuffer communication channel. The webR REPL and Shinylive set the required HTTP headers to enable that feature, but the Quarto preview server (and also many deployment targets like GitHub Pages...) do not.

The latter is harder to fix, we normally work around it in webR and Quarto Live by falling back to using the PostMessage communication channel. This works most of the time, but significantly for this issue, not for curl requests.

I will report back on this when there has been progress on either 1) or 2). We might require another minimal Quarto extension to add and enable coi-serviceworker on the page.

[rubenarslan]

Cool! I have a few use cases for teaching and dashboard-y stuff, so this would be great.