Mewz

Mewz is a unikernel designed specifically for running Wasm applications and compatible with WASI.

What's new with Mewz

There are now various Wasm runtimes, but they operate on general-purpose operating systems such as Linux or Windows.

Mewz is a specialized kernel designed for running Wasm. Mewz runs a single Wasm application within the kernel by linking it together during the build process with the Wasm application. (A kernel composed in this manner is commonly referred to as a unikernel.) In this way, Mewz provides the minimal required features and environment for executing Wasm.

Quick Start

There are some example programs. Please check out examples.

Option1: Docker

We prepare for a Docker image that has a environment for running Mewz.

curl -o helloworld.wat https://raw.githubusercontent.com/Mewz-project/Wasker/main/helloworld.wat
docker run -v .:/volume ghcr.io/mewz-project/mewz helloworld.wat

This image internally run Wasker, build Mewz, and run it on QEMU.

Option2: Dev Container

You can use Dev Container on GitHub Codespaces or your local VSCode.

To start Codespaces,

• Click Code -> Codespaces -> New codespace on this repository page.
• Wait for a while, then you can see VSCode on browser.
• Open terminal on VSCode

# On the Dev Container
git submodule update --init
curl -o helloworld.wat https://raw.githubusercontent.com/Mewz-project/Wasker/main/helloworld.wat
wasker helloworld.wat
zig build -Dapp-obj=wasm.o run

Option3: Build from source

Compile a Wasm file into a native object file, using Wasker. Follow the instruction here.

Then, build Mewz and run it on QEMU with the following commands.

zig build -Dapp-obj=<path to the object file generated by Wasker> run

To use file systems, specify the directory by -Ddir=<path to dir>. See examples/static_file_server.

Warning

This option makes an archive of the directory by tar and attach it to QEMU.

Note

QEMU's port 1234 is mapped to localhost:1234.

Development

GDB

You can debug Mewz with GDB. When you run Mewz with QEMU, it listens on port 12345 for GDB. You can connect to it by just running GDB at the root of the repository as .gdbinit is already configured.

zig build -Dapp-obj=<path to the object file generated by Wasker> run
# In another terminal
gdb

zig build debug command prevent Mewz from booting up until GDB connects to it. This is useful when you want to debug the boot process.

zig build -Dapp-obj=<path to the object file generated by Wasker> debug
# In another terminal
gdb

Run integration tests

zig bulid -Dtest=true run

Current Status

Feature	Status
WASI Preview 1	In Progress: Partial Implementation (Please refer to #1)
Socket	✅ (WasmEdge Compatible)
Component Model	Not yet
File System	On memory, read only
Network	✅