Building Plugins

Bulwark's plugins target the WebAssembly (WASM) instruction format and use the WebAssembly System Interface (WASI) API to communicate with their host environment. Currently, Bulwark only offers support for a Rust SDK, however other language support is planned.

The Rust SDK requires a Cargo.toml file in the plugin directory. This declares a plugin's dependencies and includes useful metadata like the plugin name and author information.

Rust

cargo.toml

[package]
name = "example-plugin"
version = "0.1.0"
edition = "2021"
publish = false

[dependencies]
bulwark-wasm-sdk = "0.3.0"

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

# These settings may help optimize file size for release builds
[profile.release]
lto = true
opt-level = 3
codegen-units = 1
panic = "abort"
strip = "debuginfo"

Plugin logic will be written in a src/lib.rs file.

Rust

src/lib.rs

use bulwark_wasm_sdk::*;

struct ExamplePlugin;

#[bulwark_plugin]
impl Handlers for ExamplePlugin {
    fn on_request_decision() -> Result {
        // Plugin logic goes here
        Ok(())
    }
}

A build subcommand is included in the bulwark-cli binary and should generally be used to compile Bulwark plugins.

bulwark-cli build

The default location for build output is the dist/ directory.