Demo WASM and Docker Integration

Learn how to compile a simple C program to WebAssembly (WASM) using a WASI-compatible compiler and then package it into a Docker image with a minimal runtime.

Docker’s WASM integration is currently a beta feature available in a special technical-preview build of Docker Desktop. Refer to Docker’s experimental WASM support when testing locally.

Prerequisites

Tool	Version	Purpose
Clang (WASI SDK)	v16+	Compile C to WASM via WASI
Docker Desktop	Latest (technical preview)	Build and run WASM containers
WasmEdge	v0.14+	Execute the WASM binary inside Docker

1. Write a simple C program

Create a file named helloworld.c:

#include <stdio.h>

int main() {
    printf("hello, world\n");
    return 0;
}

2. Compile to a WASM binary

Use the WASI SDK’s Clang to target wasm32-wasi:

clang --target=wasm32-wasi -O3 helloworld.c -o helloworld.wasm

This produces a standalone helloworld.wasm in your working directory.

3. Create the Dockerfile

We’ll build FROM scratch so the final image only contains the WASM binary:

FROM scratch
COPY helloworld.wasm /helloworld.wasm
ENTRYPOINT [ "/helloworld.wasm" ]

Save this as Dockerfile alongside helloworld.wasm.

4. Build the Docker image

Run:

cd path/to/your/project
docker build --platform=wasm/wasm32 -t helloworld-wasm .

The --platform=wasm/wasm32 flag instructs Docker to treat this as a WASM container.

5. Run the WASM container

Execute with the WasmEdge runtime support in containerd:

docker run --rm \
  --name wasm-docker-c-program \
  --runtime=io.containerd.wasmedge.v1 \
  helloworld-wasm

You should see:

hello, world

Congratulations! You’ve compiled a C program to WebAssembly and run it inside a Docker container.

Links and References

Watch Video

Exploring WebAssembly WASM and Docker

WASM Tools and Frameworks WasmCloud Fermyon Spin framework

Introduction

Introduction to WebAssembly (WASM)

WebAssembly Core Concepts

Getting Started with WebAssembly

Compiling to WebAssembly

Future: WebAssembly in Cloud

Community & Resources

Demo WASM and Docker Integration

Prerequisites

1. Write a simple C program

2. Compile to a WASM binary

3. Create the Dockerfile

4. Build the Docker image

5. Run the WASM container

Links and References

Watch Video

​Prerequisites

​1. Write a simple C program

​2. Compile to a WASM binary

​3. Create the Dockerfile

​4. Build the Docker image

​5. Run the WASM container

​Links and References

Watch Video

Prerequisites

1. Write a simple C program

2. Compile to a WASM binary

3. Create the Dockerfile

4. Build the Docker image

5. Run the WASM container

Links and References