Bazel Rules for WebAssembly Component Model

Modern Bazel rules for building and composing WebAssembly components.

Features

• 🚀 Component Model Support: Full support for WASM Component Model and WIT
• 🦀 Rust Integration: Seamless integration with rules_rust
• 🐹 Go Integration: TinyGo v0.38.0 with WASI Preview 2 component support
• 🔧 Toolchain Management: Automatic wasm-tools and wit-bindgen setup
• 📦 Composition: WAC-based component composition with OCI registry support
• 🐳 OCI Publishing: Publish and distribute components via container registries
• 🔐 Digital Signing: Component signing with wasmsign2 and verification
• 🏗️ Enterprise Architecture: Multi-registry microservices with security policies
• 🎯 Type Safety: Strongly typed WIT interfaces
• ⚡ Performance: Optimized builds with proper caching

Installation

Add to your MODULE.bazel:

bazel_dep(name = "rules_wasm_component", version = "1.0.0")

# Optional: Configure WASM toolchain version
wasm_toolchain = use_extension(
    "@rules_wasm_component//wasm:extensions.bzl",
    "wasm_toolchain",
)
wasm_toolchain.register(
    name = "wasm_tools",
    version = "1.0.60",  # Optional, defaults to latest stable
)

# Optional: Configure TinyGo toolchain version
tinygo = use_extension("//wasm:extensions.bzl", "tinygo")
tinygo.register(
    name = "tinygo",
    tinygo_version = "0.38.0"  # Optional, defaults to 0.38.0
)

Quick Start

1. Define WIT Interfaces

load("@rules_wasm_component//wit:defs.bzl", "wit_library")

wit_library(
    name = "my_interfaces",
    srcs = ["my-interface.wit"],
    deps = ["//wit/deps:wasi-io"],
)

2. Build Rust WASM Component

load("@rules_wasm_component//rust:defs.bzl", "rust_wasm_component")

rust_wasm_component(
    name = "my_component",
    srcs = ["src/lib.rs"],
    wit = ":my_interfaces",
    deps = [
        "//third_party/rust:wit_bindgen",
    ],
)

2b. Build Go WASM Component

load("@rules_wasm_component//go:defs.bzl", "go_wasm_component")

go_wasm_component(
    name = "my_go_component",
    srcs = ["main.go", "logic.go"],
    wit = "my-interface.wit",
    world = "my-world",
    go_mod = "go.mod",
    adapter = "//wasm/adapters:wasi_snapshot_preview1",
)

3. Compose Components

load("@rules_wasm_component//wac:defs.bzl", "wac_compose")

wac_compose(
    name = "my_system",
    components = {
        "frontend": ":frontend_component",
        "backend": ":backend_component",
    },
    composition = """
        let frontend = new frontend:component { ... };
        let backend = new backend:component { ... };

        connect frontend.request -> backend.handler;

        export frontend as main;
    """,
)

Rules

WIT Rules

• wit_library - Process WIT interface files
• wit_bindgen - Generate language bindings from WIT

Rust Rules

• rust_wasm_component - Build Rust WASM components
• rust_wasm_component_test - Test WASM components

Go Rules

• go_wasm_component - Build Go WASM components with TinyGo
• go_wit_bindgen - Generate Go bindings from WIT interfaces

Composition Rules

• wac_compose - Compose multiple components
• wac_compose_with_oci - Compose local and OCI registry components
• wac_microservices_app - Microservices composition pattern
• wac_distributed_system - Distributed system composition pattern
• wasm_component_new - Convert modules to components

OCI Publishing Rules

• wasm_component_oci_image - Prepare OCI images for components
• wasm_component_publish - Publish components to registries
• wasm_component_from_oci - Pull components from OCI registries
• wkg_registry_config - Configure registry authentication
• wkg_multi_registry_publish - Publish to multiple registries

Security Rules

• wasm_keygen - Generate signing key pairs
• wasm_sign - Sign WebAssembly components
• wasm_security_policy - Define security policies
• wasm_component_secure_publish - Policy-enforced publishing

Analysis Rules

• wasm_validate - Validate WASM components
• wit_lint - Lint WIT interfaces

Examples

See the examples/ directory for complete examples:

Core Examples

• Basic Component - Simple component with WIT
• Go Component - TinyGo WASM components
• JavaScript Component - JS components with ComponentizeJS
• C++ Component - Native C++ component development

Composition and Architecture

• WAC Remote Compose - Remote component composition
• WAC + OCI Composition - OCI registry integration
• Microservices Architecture - Production-ready microservices
• Multi-Language Composition - Polyglot component systems

OCI and Distribution

• OCI Publishing - Container registry publishing
• Component Signing - Digital signatures with wasmsign2

Advanced Features

• Wizer Pre-initialization - Startup optimization
• Wasmtime Runtime - Custom runtime integration
• Multi-Profile Components - Development vs production builds

Documentation

For Developers

• Rule Reference
• Migration Guide
• Best Practices
• Troubleshooting

For AI Agents

• AI Agent Guide - Structured documentation for AI coding assistants
• Rule Schemas - Machine-readable rule definitions
• Examples - Progressive complexity examples:
  • Basic - Fundamental patterns
  • Intermediate - Cross-package dependencies
  • Advanced - Complex compositions and custom rules

Contributing

Contributions are welcome! Please read our Contributing Guide.

Development Setup

This project uses pre-commit hooks for code quality:

# Install pre-commit
pip install pre-commit

# Install hooks
pre-commit install
pre-commit install --hook-type commit-msg

# Test setup
pre-commit run --all-files

See Pre-commit Instructions for detailed setup.

License

Apache 2.0 - See LICENSE for details.