fn-serverless/examples/tutorial/hello/rust/README.md

Tutorial 1: Rust Function w/ Input (3 minutes)

This example will show you how to test and deploy Rust code to Oracle Functions. It will also demonstrate passing data in through stdin.

The easiest way to create a function in rust is via cargo and fn.

Prerequisites

Create an empty rust project as follows:

cargo init --name func --bin

Make sure the project name is func and is of type bin.

Now put the following code in main.rs (can also copy directly from the file in this repo):

use std::io;
use std::io::Read;

fn main() {
    let mut buffer = String::new();
    let stdin = io::stdin();
    if stdin.lock().read_to_string(&mut buffer).is_ok() {
        println!("Hello {}", buffer.trim());
    }
}

Now run the following commands:

# Initialize your function creating a func.yaml file
fn init --name hello-rust

# Test your function. This will run inside a container exactly how it will on the server
fn run

# Now try with an input (copy sample.payload.json from this repo)
cat sample.payload.json | fn run

# Deploy your functions to the Oracle Functions server (default localhost:8080)
# This will create a route to your function as well
fn deploy --app myapp

Now call your function:

curl http://localhost:8080/r/myapp/hello-rust

Or call from a browser: http://localhost:8080/r/myapp/hello-rust

And now with the JSON input:

curl -H "Content-Type: application/json" -X POST -d @sample.payload.json http://localhost:8080/r/myapp/hello-rust

That's it!

Note on Dependencies

In Review

1. We piped JSON data into the function at the command line

   cat sample.payload.json | fn run
   

2. We received our function input through stdin

   read_to_string(&mut buffer)
   

3. We wrote our output to stdout

   println!("Hello {}", buffer.trim());
   

4. We sent stderr to the server logs

   TODO
   

Next Up

Part 2: Input Parameters