ZLayer Rust SDK

Plugin Development Kit for building WASM plugins in Rust targeting ZLayer.

Requirements

• Rust 1.85+ (edition 2024)
• cargo-component for WASM compilation

Installation

Add to your Cargo.toml:

[package]
name = "my-plugin"
version = "0.1.0"
edition = "2024"

[lib]
crate-type = ["cdylib"]

[dependencies]
zlayer-sdk = "0.1"

[package.metadata.component]
package = "zlayer:plugin"

Development Setup

# Install cargo-component
cargo install cargo-component

# Clone and build the SDK
cd clients/zlayer-sdk/rust
cargo build

Usage

Basic Plugin Structure

use zlayer_sdk::prelude::*;

struct MyPlugin;

impl Handler for MyPlugin {
    fn handle(&self, request: Request) -> Response {
        // Access key-value storage
        let value = kv::get("my-key");

        // Log messages to host
        log::info("Processing request");

        // Return response
        Response::ok(b"Hello from ZLayer!")
    }
}

// Export the handler to ZLayer runtime
export_handler!(MyPlugin);

Building WASM Component

# Build with cargo-component
cargo component build --release

# Output will be in target/wasm32-wasip2/release/my_plugin.wasm

Available Host Capabilities

The SDK provides access to ZLayer host functions:

• config - Plugin configuration access
• kv - Key-value storage operations
• log - Structured logging
• secrets - Secure secret retrieval
• metrics - Emit custom metrics
• http - Outbound HTTP requests (WASI HTTP)

Plugin Worlds

ZLayer supports multiple plugin worlds for different use cases:

Selecting a World

Specify the world in your Cargo.toml:

[package.metadata.component]
package = "zlayer:plugin"
world = "zlayer-http-handler"

Project Structure

src/
  lib.rs           # Main library with bindings
examples/
  hello.rs         # Basic hello world plugin
wit/               # Symlink to WIT definitions

Testing

# Run unit tests
cargo test

# Test with the ZLayer runtime (requires zlayer CLI)
zlayer plugin test ./target/wasm32-wasip2/release/my_plugin.wasm

Type Safety

All bindings are generated from WIT definitions at compile time, providing:

• Compile-time type checking
• IDE autocompletion
• Documentation from WIT comments

License

MIT OR Apache-2.0