hwclass/docker-beta-wasm-example

🚀 A simple example demonstrating how to run WebAssembly modules in Docker (Beta)

Docker (Beta) with WASM

🚀 A simple example demonstrating how to run WebAssembly modules in Docker (Beta)

Prerequisites

• Docker Desktop (Latest version)
• Rust (for building the WASM module)
• Git

Project Structure

docker-wasm-example/
├── src/
│   └── main.rs
├── Cargo.toml
├── .dockerignore
├── Dockerfile
└── README.md

Setup Instructions

1. Enable WASM Support in Docker Desktop

1. Open Docker Desktop
2. Navigate to Settings (gear icon)
3. In the General tab, ensure "Use containerd for pulling and storing images" is enabled

4. Go to Features in development
5. Check "Enable Wasm"

6. Click Apply & restart
7. In the confirmation dialog, click Install to install the WASM runtimes
8. Wait for Docker Desktop to restart

2. Create Project Files

Create a new Rust project:

cargo new docker-wasm-example
cd docker-wasm-example

Create Cargo.toml:

[package]
name = "wasm-example"
version = "0.1.0"
edition = "2021"

[dependencies]
anyhow = "1.0"

[lib]
crate-type = ["cdylib"]

Create src/main.rs:

use std::prelude::v1::*;

fn main() -> anyhow::Result<()> {
    println!("Hello from WASM!");
    Ok(())
}

Create .dockerignore:

target/
Cargo.lock

Create Dockerfile:

# syntax=docker/dockerfile:1
FROM --platform=$BUILDPLATFORM rust:1.70-slim as builder

WORKDIR /app

# Install required dependencies
RUN apt-get update && apt-get install -y \
    cmake \
    && rm -rf /var/lib/apt/lists/*

# Install WASI target
RUN rustup target add wasm32-wasi

# Copy project files
COPY . .

# Build for WASI target
RUN cargo build --target wasm32-wasi --release

FROM scratch
COPY --from=builder /app/target/wasm32-wasi/release/wasm-example.wasm /app.wasm
ENTRYPOINT [ "/app.wasm" ]

3. Build and Run

1. Create and use a new builder for WASM:

docker buildx rm wasm-builder --force
docker buildx create --name wasm-builder --driver docker-container --bootstrap
docker buildx use wasm-builder

2. Build the WASM container:

docker buildx build \
    --platform wasi/wasm32 \
    --build-arg BUILDPLATFORM=$(docker version -f '{{.Server.Os}}/{{.Server.Arch}}') \
    --load \
    -t wasm-example .

3. Run the container with different runtimes:

WasmEdge (Recommended for general use)

docker run --runtime=io.containerd.wasmedge.v1 --platform=wasi/wasm32 wasm-example

Wasmer

docker run --runtime=io.containerd.wasmer.v1 --platform=wasi/wasm32 wasm-example

Wasmtime

docker run --runtime=io.containerd.wasmtime.v1 --platform=wasi/wasm32 wasm-example

Slight

docker run --runtime=io.containerd.slight.v1 --platform=wasi/wasm32 wasm-example

Spin

docker run --runtime=io.containerd.spin.v2 --platform=wasi/wasm32 wasm-example

Lunatic

docker run --runtime=io.containerd.lunatic.v1 --platform=wasi/wasm32 wasm-example

WWS (Wasm Workers Server)

docker run --runtime=io.containerd.wws.v1 --platform=wasi/wasm32 wasm-example

Runtime Comparison

| Runtime | Best For | Key Features |
|---------|----------|--------------|
| WasmEdge | General purpose | Good performance, broad compatibility |
| Wasmer | Production | Strong ecosystem, good performance |
| Wasmtime | Development | Fast startup, good debugging |
| Slight | Lightweight apps | Minimal resource usage |
| Spin | Web services | HTTP-focused features |
| Lunatic | Distributed systems | Actor-based concurrency |
| WWS | Worker systems | Background processing |

Troubleshooting

Common Issues

1. Builder exists error

docker buildx rm wasm-builder --force
docker buildx create --name wasm-builder --driver docker-container --bootstrap

2. Runtime not found

docker info | grep wasm

3. Build fails

# Clean Docker build cache
docker builder prune
# Remove and recreate builder
docker buildx rm wasm-builder
docker buildx create --name wasm-builder --driver docker-container --bootstrap

4. WASI dependencies error

rustup target add wasm32-wasi --force
cargo clean

Contributing

Feel free to submit issues and enhancement requests!

License

MIT

---

🔧 Built with ❤️ using Docker WASM support

Key changes:

1. Updated Cargo.toml with proper dependencies and crate type
2. Added proper error handling in main.rs
3. Simplified Dockerfile build process
4. Added comprehensive runtime comparison table
5. Added examples for all available runtimes
6. Updated troubleshooting section with WASI-specific issues

Citations: [1] https://ppl-ai-file-upload.s3.amazonaws.com/web/direct-files/7954569/b3c29962-c5b2-4755-b9a7-f6ac868bd5a7/paste.txt