wasmic

A CLI tool for managing WASI components and running them as MCP (Model Context Protocol) servers. See components for use

What it does

Wasic enables you to run WebAssembly components as MCP (Model Context Protocol) servers, giving you access to a wide range of tools and functionality through a unified interface. With wasmic, you can:

• Deploy and manage WebAssembly tools from local files or remote OCI registries
• Expose WASM component functions as MCP tools that can be used by AI assistants and other MCP clients
• Run sandboxed, cross-platform tools without worrying about installation conflicts or system dependencies
• Integrate with AI workflows by making WebAssembly capabilities available through the Model Context Protocol
• Configure and customize component behavior through simple YAML configuration files

Features

• Accepts both local file paths and OCI URLs for WASM components
• Uses wasm-tools and wkg for component manipulation
• Built on wasmtime for executing WASM components
• Integrates with MCP (Model Context Protocol) servers
• Supports component configuration and profiling

Installation

From GitHub Releases (Recommended)

Pre-compiled binaries for Linux (x86_64), macOS (x86_64 and ARM64), and Windows (x86_64) are available on the GitHub Releases page. This is the recommended way to install wasmic for most users.

Download the appropriate archive for your system, extract it, and place the wasmic (or wasmic.exe on Windows) binary in your system's PATH.

Using cargo-binstall

For easy installation from crates.io (once published):

cargo binstall wasmic

From Cargo

To install the latest version from source via Cargo:

cargo install wasmic

From Source

To install the latest development version from source:

# Clone the repository
git clone https://github.com/dineshdb/wasmic.git
cd wasmic

# Install the CLI tool
just install

Configuration

Default Configuration File

The default configuration file is config.yaml in the project root. It defines:

• Profiles for different environments
• Component configurations
• OCI registry settings
• MCP server settings

Configuration Locations

The wasmic CLI looks for configuration files in the following order:

1. Command-line argument (--config)
2. Environment variable (WASIC_CONFIG)
3. Default locations:
   • Linux/macOS: ~/.config/wasmic/config.yaml
   • macOS: ~/Library/Application Support/wasmic/config.yaml

Cache Folder

Wasic uses a cache folder for storing downloaded OCI artifacts and other temporary files:

• Linux: ~/.cache/wasmic/
• macOS: ~/Library/Caches/wasmic/
• Windows: %LOCALAPPDATA%\wasmic\cache\

Usage

Basic Commands

# List available components
wasmic --config config.yaml list

# Call a function on a component
wasmic --config config.yaml call --function "time.get-current-time" --args "{}"

# Call fetch function
wasmic --config config.yaml call --function "fetch.fetch" --args '{"url":"https://httpbin.org/get"}'

Configuration

Create a config.yaml file to define your components:

profiles:
  default:
    components:
      time:
        path: target/wasm32-wasip2/release/time.wasm
        config:
          timezone: "UTC"
      fetch:
        path: target/wasm32-wasip2/release/fetch.wasm

Or use OCI references:

profiles:
  default:
    components:
      time:
        oci: ghcr.io/dineshdb/wasmic-components/time:v0.1.0
        config:
          timezone: "UTC"
      fetch:
        oci: ghcr.io/dineshdb/wasmic-components/fetch:v0.1.0

Building Components

# Build all WASM components
just build

# Build specific component
just _build time
just _build fetch

MCP Server Usage

Running as MCP Server

Wasic can run as a standalone MCP server that exposes WASM components as MCP tools:

# Start MCP server with default config
wasmic mcp

# Start with custom config
wasmic mcp --config /path/to/config.yaml

# Start on specific host and port
wasmic mcp --http 0.0.0.0:8080

MCP Integration

Wasic integrates with MCP (Model Context Protocol) to expose WASM components as tools that can be used by MCP clients. The server automatically:

• Loads components from the configuration
• Generates tool definitions based on WIT interfaces
• Handles tool execution requests
• Manages component lifecycle and state

Example Components

Time Component

• Function: get-current-time
• Returns: Current time as string
• Configurable timezone support

Fetch Component

• Function: fetch
• Input: URL string
• Returns: HTTP response content as string

Dependencies

• wkg: For OCI artifact pulling
• wasm-tools: For WASM component manipulation
• wasmtime: For WASM runtime execution
• rmcp: For MCP server functionality
• clap: For command-line interface

Development

For development information, see docs/development.md.

Example WASIP2 Component

For testing, you can use: ghcr.io/yoshuawuyts/time:latest