Wasm/WASI for MSBuild

• MSBuild task is an unit of execution inside a build, that can be created by users of MSBuild
• experimental project exporing using Wasm/WASI to create MSBuild tasks
• Wasm/WASI supports multiple languages extending the notion of a MSBuild Task from a C# class to a Wasm module
  • Rust example tasks [examples/]
• The tasks run in a Wasm/WASI runtime - Wasmtime which sandboxes the execution from the rest of the system and files/directories a task allowed to touch have to be specified.

see spec for details

User manual

Create a MSBuild task using Wasm/WASI toolchain.

1. install wasi-sdk, cargo, build the .dll for MSBuildWasm (e.g. by dotnet publish src)
2. copy rust_template from the examples folder and add your behavior to the lib.rs file, take care to specify the input/output parameters
3. compile with cargo build --release --target wasm32-wasi
4. in your project's project.csproj that you want to build with MSBuild include the task

<UsingTask TaskName="MyWasmTask" AssemblyFile="MSBuildWasm.dll" TaskFactory="WasmTaskFactory">
<Task>your_module.wasm</Task>
</UsingTask>

3. use the task in a target

<Target Name="MyWasmTarget" AfterTargets="Build">
  <MyWasmTask Param="StringParam" Param2="true">
      <Output TaskParameter="Result" PropertyName="TaskResult"/>
  </MyWasmTask>
</Target>

4. dotnet build

Inputs and outputs from a tasks can be bools, strings and "ITaskItem" which is basically a file path.

Writing tasks for MSBuild