CompileError: WebAssembly.instantiate(): Wasm code generation disallowed by embedder

Hey folks,

I'm trying to run a wasm file compiled by emscripten on CF workers. It's working fine locally, but when I try it in production I get:

failed to asynchronously prepare wasm: CompileError: WebAssembly.instantiate(): Wasm code generation disallowed by embedder

failed to asynchronously prepare wasm: CompileError: WebAssembly.instantiate(): Wasm code generation disallowed by embedder

failed to asynchronously prepare wasm: CompileError: WebAssembly.instantiate(): Wasm code generation disallowed by embedder

failed to asynchronously prepare wasm: CompileError: WebAssembly.instantiate(): Wasm code generation disallowed by embedder

This page seems to indicate that

WebAssembly.instantiate

WebAssembly.instantiate

WebAssembly.instantiate

WebAssembly.instantiate should work, am I missing something?

https://developers.cloudflare.com/workers/runtime-apis/webassembly/

WebAssembly (Wasm) · Cloudflare Workers docs

Execute code written in a language other than JavaScript or write an entire Cloudflare Worker in Rust.

kian•1/31/24, 4:46 PM

The module can't be inlined as a buffer, it needs to be uploaded as a separate .wasm file

xeon06OP•1/31/24, 6:18 PM

Thanks for taking the time to answer. It is; the emscripten glue is fetching it

xeon06OP•1/31/24, 6:19 PM

The error happens on instantiateinstantiate, but the

fetch

fetch

code before works without error:

xeon06OP•1/31/24, 6:19 PM

function Ea(a) {
    return y || "function" != typeof fetch ? Promise.resolve().then(function() {
        return Da(a)
    }) : fetch(a, {
        credentials: "same-origin"
    }).then(function(b) {
        if (!b.ok) throw "failed to load wasm binary file at '" + a + "'";
        return b.arrayBuffer()
    }).catch(function() {
        return Da(a)
    })
}

function Fa(a, b, c) {
    return Ea(a).then(function(d) {
        return WebAssembly.instantiate(d, b)
    }).then(function(d) {
        return d
    }).then(c, function(d) {
        w("failed to asynchronously prepare wasm: " + d);
        z(d)
    })
}

function Ea(a) {
    return y || "function" != typeof fetch ? Promise.resolve().then(function() {
        return Da(a)
    }) : fetch(a, {
        credentials: "same-origin"
    }).then(function(b) {
        if (!b.ok) throw "failed to load wasm binary file at '" + a + "'";
        return b.arrayBuffer()
    }).catch(function() {
        return Da(a)
    })
}

function Fa(a, b, c) {
    return Ea(a).then(function(d) {
        return WebAssembly.instantiate(d, b)
    }).then(function(d) {
        return d
    }).then(c, function(d) {
        w("failed to asynchronously prepare wasm: " + d);
        z(d)
    })
}

kian•1/31/24, 6:20 PM

Fetch as in from a URL? That's basically the same thing as loading it as a Buffer.

xeon06OP•1/31/24, 6:20 PM

Yeah fetched from a URL

xeon06OP•1/31/24, 6:20 PM

How should I proceed?

xeon06OP•1/31/24, 6:20 PM

Does it need to be like bundled in?

xeon06OP•1/31/24, 6:21 PM

My understanding was that .wasm code is typically fetched over the network, and I was thinking this would help with worker bundle size given the wasm file is almost 1mb itself

kian•1/31/24, 6:22 PM

It needs to be bundled

xeon06OP•1/31/24, 6:29 PM

Sorry I'm slightly confused, above when you said "it needs to be uploaded as a separate .wasm file", that's not contrary to the idea of bundling it?

xeon06OP•1/31/24, 7:19 PM

I assume something like this https://vitejs.dev/guide/features#webassembly which will include it in the bundle. I also realized that paid is now 10mb. I'll give that a go, thanks for the help.

CompileError: WebAssembly.instantiate(): Wasm code generation disallowed by embedder

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