https://github.com/pulseengine/rules_wasm_component
Bazel rules for WebAssembly Component Model development with multi-profile builds and dependency management
https://github.com/pulseengine/rules_wasm_component
bazel component-model pulseengine rust toolchain webassembly
Last synced: about 1 month ago
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Bazel rules for WebAssembly Component Model development with multi-profile builds and dependency management
- Host: GitHub
- URL: https://github.com/pulseengine/rules_wasm_component
- Owner: pulseengine
- License: apache-2.0
- Created: 2025-07-06T13:12:10.000Z (11 months ago)
- Default Branch: main
- Last Pushed: 2026-04-13T11:36:59.000Z (about 2 months ago)
- Last Synced: 2026-04-13T13:30:09.100Z (about 2 months ago)
- Topics: bazel, component-model, pulseengine, rust, toolchain, webassembly
- Language: Starlark
- Homepage: https://rules-wasm-component.pulseengine.eu/
- Size: 189 MB
- Stars: 1
- Watchers: 0
- Forks: 0
- Open Issues: 10
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Agents: AGENTS.md
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README
# rules_wasm_component
Bazel rules for WebAssembly Component Model
Production-ready Bazel rules for building WebAssembly components across multiple languages with native WASI 0.2 support.
> [!NOTE]
> Part of the PulseEngine toolchain. Used across all PulseEngine projects for hermetic component builds.
## Why Use This?
- **Multi-language**: Build components from Rust, Go (TinyGo), C++, JavaScript/TypeScript
- **Production Ready**: OCI publishing, cryptographic signing, WAC composition, AOT compilation
- **Bazel Native**: Hermetic builds, aggressive caching, cross-platform (Windows/macOS/Linux)
- **Zero Shell Scripts**: Pure Bazel implementation for maximum portability
## Installation
Add to your `MODULE.bazel`:
```starlark
bazel_dep(name = "rules_wasm_component", version = "1.0.0")
```
## Quick Examples
### Rust Component
```starlark
load("@rules_wasm_component//rust:defs.bzl", "rust_wasm_component")
rust_wasm_component(
name = "my_service",
srcs = ["src/lib.rs"],
wit = ":service_wit",
profiles = ["debug", "release"],
)
```
### Go Component (TinyGo 0.39.0+)
```starlark
load("@rules_wasm_component//go:defs.bzl", "go_wasm_component")
go_wasm_component(
name = "calculator",
srcs = ["main.go"],
wit = ":calculator_wit",
world = "calculator",
)
```
### C++ Component (WASI SDK 27+)
```starlark
load("@rules_wasm_component//cpp:defs.bzl", "cpp_component")
cpp_component(
name = "calculator",
srcs = ["calculator.cpp"],
wit = ":calculator_wit",
cxx_std = "c++20",
)
```
### WAC Composition
```starlark
load("@rules_wasm_component//wac:defs.bzl", "wac_compose")
wac_compose(
name = "full_system",
components = {
":frontend": "app:frontend",
":backend": "app:backend",
},
composition = '''
let frontend = new app:frontend { ... };
let backend = new app:backend { ... };
connect frontend.request -> backend.handler;
export frontend as main;
''',
)
```
## Features
### Language Support
- **Rust** (1.90.0+): Multi-profile builds, Clippy integration, Wizer pre-initialization
- **Go** (TinyGo 0.39.0): Native WASI 0.2, hermetic Go module resolution
- **C++** (WASI SDK 27): C++17/20/23, cross-package headers, LTO optimization
- **JavaScript/TypeScript** (jco 1.4.0, Node.js 20.18.0): NPM dependencies, componentize-js
### Production Features
- **WAC Composition**: Official WebAssembly Composition standard for multi-component systems
- **OCI Publishing**: Push components to Docker/OCI registries
- **Cryptographic Signing**: wasmsign2 integration for supply chain security
- **AOT Compilation**: Wasmtime precompilation for 87% size reduction and faster startup
- **Wizer Pre-initialization**: 1.35-6x startup improvement for Rust components
- **Multi-Profile Builds**: Debug, release, and custom optimization profiles
### Developer Experience
- **Hermetic Toolchains**: All tools downloaded automatically, no system dependencies
- **Cross-Platform**: Native Windows/macOS/Linux support without WSL
- **Comprehensive Examples**: 20+ working examples from basic to advanced patterns
## Toolchain Versions
**See [MODULE.bazel](MODULE.bazel) for current versions** — the single source of truth.
All toolchains are hermetically downloaded and version-pinned for reproducible builds.
## Documentation
**[Complete Rule Reference](docs/rules.md)** — All rules, attributes, and providers
**Guides:**
- [Toolchain Configuration](docs/toolchain_configuration.md)
- [Multi-Profile Builds](docs/multi_profile.md)
- [Development Guidelines](CLAUDE.md)
**Examples:**
- [Basic Component](examples/basic/)
- [Multi-Language Composition](examples/multi_language_composition/)
- [Wizer Pre-initialization](examples/wizer_example/)
- [OCI Publishing](examples/oci_publishing/)
- [See all examples](examples/)
## Known Limitations
### Go WIT Components (Temporary)
- WIT-enabled Go components currently fail due to upstream TinyGo limitations
- Tracking: [Issue #82](https://github.com/pulseengine/rules_wasm_component/issues/82)
- Basic Go components (without WIT) work perfectly
### C++ Exception Handling
- WASI disables C++ exceptions by default for size/performance
- Use `enable_exceptions = True` for components that require exceptions ([Issue #83](https://github.com/pulseengine/rules_wasm_component/issues/83))
## Contributing
Contributions welcome! See [CONTRIBUTING.md](CONTRIBUTING.md) for details.
## License
Apache-2.0 — see [LICENSE](LICENSE).
---
Part of PulseEngine — formally verified WebAssembly toolchain for safety-critical systems