Sample OpenWhisk Action using Rust

main.rs

extern crate rustc_serialize;
use rustc_serialize::json;
use rustc_serialize::json::Json;
use std::env;

#[derive(RustcDecodable, RustcEncodable)]
pub struct Greeting {
    message: String
}

fn main() {
    let mut name = "stranger".to_string();

    // first arg contains JSON parameters
    if let Some(arg1) = env::args().nth(1) {
        // parse JSON and extract 'name' field
        let params = Json::from_str(&arg1).unwrap();
        if let Some(params_obj) = params.as_object() {
            if let Some(params_name) = params_obj.get("name") {
                name = params_name.as_string().unwrap().to_string();
            }
        }
    };

    let greeting = Greeting {
        message: format!("Hello, {}!", name),
    };

    println!("{}", json::encode(&greeting).unwrap());
}