This section describes everything required to build and run Wasmtime.


Before we can actually build Wasmtime, we'll need to make sure these things are installed first.

Git Submodules

The Wasmtime repository contains a number of git submodules. To build Wasmtime and most other crates in the repository, you have to ensure that those are initialized with this command:

git submodule update --init

The Rust Toolchain

Install the Rust toolchain here. This includes rustup, cargo, rustc, etc...

libclang (optional)

The wasmtime-fuzzing crate transitively depends on bindgen, which requires that your system has a libclang installed. Therefore, if you want to hack on Wasmtime's fuzzing infrastructure, you'll need libclang. Details on how to get libclang and make it available for bindgen are here.

Building the wasmtime CLI

To make an unoptimized, debug build of the wasmtime CLI tool, go to the root of the repository and run this command:

cargo build

The built executable will be located at target/debug/wasmtime.

To make an optimized build, run this command in the root of the repository:

cargo build --release

The built executable will be located at target/release/wasmtime.

You can also build and run a local wasmtime CLI by replacing cargo build with cargo run.

Building the Wasmtime C API

To build the C API of Wasmtime you can run:

cargo build --release -p wasmtime-c-api

This will place the shared library inside of target/release. On Linux it will be called libwasmtime.{a,so}, on macOS it will be called libwasmtime.{a,dylib}, and on Windows it will be called wasmtime.{lib,dll,dll.lib}.

Building Other Wasmtime Crates

You can build any of the Wasmtime crates by appending -p wasmtime-whatever to the cargo build invocation. For example, to build the wasmtime-environ crate, execute this command:

cargo build -p wasmtime-environ

Alternatively, you can cd into the crate's directory, and run cargo build there, without needing to supply the -p flag:

cd crates/environ/
cargo build