Proxy

Proxy in Rust

Proxy is a structural design pattern that provides an object that acts as a substitute for a real service object used by a client. A proxy receives client requests, does some work (access control, caching, etc.) and then passes the request to a service object.

The proxy object has the same interface as a service, which makes it interchangeable with a real object when passed to a client.

Learn more about Proxy

Conceptual Example: Nginx Proxy

A web server such as Nginx can act as a proxy for your application server:

It provides controlled access to your application server.
It can do rate limiting.
It can do request caching.

server.rs

mod application; mod nginx; pub use nginx::NginxServer; pub trait Server { fn handle_request(&mut self, url: &str, method: &str) -> (u16, String); }

server/application.rs

use super::Server; pub struct Application; impl Server for Application { fn handle_request(&mut self, url: &str, method: &str) -> (u16, String) { if url == "/app/status" && method == "GET" { return (200, "Ok".into()); } if url == "/create/user" && method == "POST" { return (201, "User Created".into()); } (404, "Not Ok".into()) } }

server/nginx.rs

use std::collections::HashMap; use super::{application::Application, Server}; /// NGINX server is a proxy to an application server. pub struct NginxServer { application: Application, max_allowed_requests: u32, rate_limiter: HashMap<String, u32>, } impl NginxServer { pub fn new() -> Self { Self { application: Application, max_allowed_requests: 2, rate_limiter: HashMap::default(), } } pub fn check_rate_limiting(&mut self, url: &str) -> bool { let rate = self.rate_limiter.entry(url.to_string()).or_insert(1); if *rate > self.max_allowed_requests { return false; } *rate += 1; true } } impl Server for NginxServer { fn handle_request(&mut self, url: &str, method: &str) -> (u16, String) { if !self.check_rate_limiting(url) { return (403, "Not Allowed".into()); } self.application.handle_request(url, method) } }

main.rs

mod server; use crate::server::{NginxServer, Server}; fn main() { let app_status = &"/app/status".to_string(); let create_user = &"/create/user".to_string(); let mut nginx = NginxServer::new(); let (code, body) = nginx.handle_request(app_status, "GET"); println!("Url: {}\nHttpCode: {}\nBody: {}\n", app_status, code, body); let (code, body) = nginx.handle_request(app_status, "GET"); println!("Url: {}\nHttpCode: {}\nBody: {}\n", app_status, code, body); let (code, body) = nginx.handle_request(app_status, "GET"); println!("Url: {}\nHttpCode: {}\nBody: {}\n", app_status, code, body); let (code, body) = nginx.handle_request(create_user, "POST"); println!("Url: {}\nHttpCode: {}\nBody: {}\n", create_user, code, body); let (code, body) = nginx.handle_request(create_user, "GET"); println!("Url: {}\nHttpCode: {}\nBody: {}\n", create_user, code, body); }

Output

Url: /app/status HttpCode: 200 Body: Ok Url: /app/status HttpCode: 200 Body: Ok Url: /app/status HttpCode: 403 Body: Not Allowed Url: /create/user HttpCode: 201 Body: User Created Url: /create/user HttpCode: 404 Body: Not Ok

Proxy in Other Languages