wash - wasmCloud Shell

This skill provides expertise in using the wasmCloud Shell (wash) CLI tool for developing and managing WebAssembly components and wasmCloud applications.

Prerequisites

• wash

  version 2.0.0 or later (including release candidates like 2.0.0-rc.X)
• Verify version with:

  wash --version

Important Notes

Do not use

cargo component

commands (like

cargo component build

) when working with wasmCloud projects. Always use

wash

commands instead:

• Use

  wash build

  or

  wash dev

  for building components
• For plugins, build with

  wash build --skip-fetch

  (since wasmcloud:wash interface isn't published)

Core Commands

wash dev

Use

wash dev

for local development and build loop. This command:

• Automatically rebuilds your component on file changes
• Provides a fast iteration cycle during development
• Watches for changes and recompiles as needed

Example:

wash dev

wash wit update

Use

wash wit update

when there are mismatched WIT (WebAssembly Interface Types) definitions. This command:

• Updates WIT dependencies to resolve conflicts
• Synchronizes WIT definitions across your project
• Fixes version mismatches in component interfaces

Example:

wash wit update

Common Workflows

Starting a New Project

1. Initialize your project with

   wash new https://github.com/cosmonic-labs/<TEMPLATE> --name my-project

2. cd my-project

3. Run

   wash build

   to build the code
4. Make changes to your code

Fixing WIT Definition Conflicts

If you encounter errors about mismatched WIT definitions:

1. Run

   wash wit update

   to synchronize definitions
2. Review the updated WIT files
3. Continue with

   wash build

Additional Resources

• wash is the primary CLI tool for the wasmCloud ecosystem
• It handles component building, testing, and deployment
• Supports both local development and production workflows