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