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Built-in WASI Support

⚠️ Experimental Feature: WASI support in Fungi CLI is experimental and may change in future releases.

Starting from version 0.4.0, Fungi CLI includes built-in support for running WebAssembly modules using the WASI (WebAssembly System Interface) standard.

It re-exports commands from the Wasmtime project, allowing you to run WebAssembly modules with WASI support directly from the Fungi CLI.

Recommended Reading: If you're new to Fungi, we recommend reading the CLI Service Quick Start guide first to understand the basics of Fungi's networking and port forwarding.

Available WASI Commands​

fungi run <wasm-file> [args...] - Runs a WebAssembly module with WASI support.

fungi serve <wasm-file> [options] - Serves a WebAssembly module as an HTTP service with wasi-http.

Example Usage​

This example demonstrates how to run a WASI module on Device A and access it remotely from Device B through Fungi's port forwarding.

Prerequisites:

  • Both Device A and Device B have Fungi daemon installed and running
  • Device B is added to Device A's incoming-allowed-peers list
  • For setup instructions, see the CLI Service Quick Start guide

We'll use spore-box, a toy WASI application that allows you to transfer files and short messages between devices.

On Device A: Download Pre-compiled WASI Module​

wget https://github.com/enbop/spore-box/releases/download/v0.2.0/spore-box.wasm

(Or build from source)

On Device A: Start Serving the WASI Module​

Create a data directory to store spore-box data:

mkdir data

Start the wasi-http server using Fungi CLI:

fungi serve --addr=127.0.0.1:8081 -Scli --dir data spore-box.wasm

(This is equivalent to running wasmtime serve --addr=127.0.0.1:8081 --dir data spore-box.wasm if you have Wasmtime installed)

  • --addr - Specifies the listening address for the HTTP server
  • -Scli - Enables the wasi-cli and other initialized modules
  • --dir data - Mounts the data directory to the WASI module for persistent storage

Note: The WASI runtime is a sandboxed environment and can only access files and directories explicitly mounted to it.

On Device A: Access the WASI Service Locally​

Now you can access the spore-box service in your browser at http://127.0.0.1:8081?device=deviceA.

The ?device=deviceA parameter sets a unique identifier for this device in the spore-box application.

On Device A: Enable Port Forwarding​

Make sure you have the Fungi daemon running. Open another terminal and add a port-listening rule to share port 8081 through Fungi:

fungi tn add-listen 127.0.0.1:8081
This operation can also be performed in the Fungi App GUI.

This allows Device B to access this WASI service through Fungi's network.

On Device B: Add Forwarding Rule​

Make sure Device B has the Fungi daemon running and is connected to Device A.

Add a port-forwarding rule to access the WASI service running on Device A:

fungi tn add-forward 127.0.0.1:18081 ${PeerID-of-DeviceA} 8081
This operation can also be performed in the Fungi App GUI.

This command forwards local port 18081 on Device B to port 8081 on Device A. You can use any available local port instead of 18081.

You can get Device A's PeerID by running fungi info id on Device A, or checking the Fungi App GUI.

On Device B: Access the WASI Service Remotely​

Now on Device B, open your browser and access http://127.0.0.1:18081?device=deviceB.

The service is now accessible as if it were running locally on Device B!

Use the Spore-Box Service​

You can now send messages or files through the spore-box web interface on either device, and they will be transferred securely between Device A and Device B via Fungi's P2P network.

spore-box screenshot