rtlambda example echo server

echo-server.rs

use rtlambda::prelude::*;
use serde::Serialize;
#[macro_use]
extern crate rtlambda;

// Create a struct representing the lambda's response.
#[derive(Serialize, Clone)]
struct EchoMessage {
    msg: String,
    req_id: String,
}

// Define output and error types for berevity.
type OUT = EchoMessage;
type ERR = String;

// Implement an initialization function.
fn initialize() -> Result<
    Box<dyn Fn(Option<&str>, RefLambdaContext<LambdaRuntimeEnv, UreqResponse>) -> Result<OUT, ERR>>,
    ERR,
> {
    // One-time initialization of reusable resources goes here
    //     
    return Ok(Box::new(move |event, context| {
        // Get the aws request id
        let req_id = context.aws_request_id().unwrap();

        // Unwrap the event string
        let event = match event {
            Some(v) => v,
            None => {
                return Err(format!(
                    "AWS should not permit empty events. Something strange must've happened."
                ))
            }
        };

        if event == "\"\"" {
            return Err(format!("Empty input, nothing to echo."));
        }

        // Echo the event back as a string.
        Ok(EchoMessage {
            msg: format!("ECHO: {}", event),
            req_id: req_id.to_string(),
        })
    }));
}

fn main() {
    // Create a runtime instance and run its loop.
    let mut runtime = default_runtime!(OUT, ERR, LAMBDA_VER, initialize);
    runtime.run();
}