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#239 in HTTP client

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reqwest-lb

Crates.io Apache licensed Build Status

A crate for reqwest support load balancer, use the reqwest-middleware.

Overview

This crate provide a middleware LoadBalancerMiddleware, it implement reqwest-middleware::Middleware, then use the lb:// instead http:// or https://

  • dependencies

    [dependencies]
    reqwest = "0.12"
    reqwest-middleware = "0.3"
    reqwest-lb = "0.1"
    
  • example

    
    use reqwest::{Client, Url};
    use reqwest_lb::supplier::LoadBalancer;
    use reqwest_lb::LoadBalancerMiddleware;
    use reqwest_lb::LoadBalancerPolicy;
    use reqwest_lb::LoadBalancerRegistry;
    use reqwest_middleware::{ClientBuilder, ClientWithMiddleware};
    
    pub fn create<const N: usize>(
        ports: [u16; N],
        policy: LoadBalancerPolicy<Url>,
    ) -> ClientWithMiddleware {
        // create load balancer factory
        let mut registry = LoadBalancerRegistry::default();
    
        // create url list
        let mut urls = Vec::with_capacity(N);
        for port in ports {
            urls.push(Url::parse(format!("http://127.0.0.1:{}", port).as_str()).unwrap());
        }
    
        // create load balancer
        let load_balancer = LoadBalancer::new(urls, policy);
    
        // register load balancer for the host: example-server
        registry.add("example-server", load_balancer);
    
        // create reqwest client
        let middleware = LoadBalancerMiddleware::new(registry);
        ClientBuilder::new(Client::builder().no_proxy().build().unwrap())
            .with(middleware)
            .build()
    }
    
    #[tokio::main]
    async fn main() {
        // use round robin policy
        let client = create([3001, 3002], LoadBalancerPolicy::RoundRobin);
        // http://127.0.0.1:3001
        let response = client.get("lb://example-server/").send().await.unwrap();
        // http://127.0.0.1:3002
        let response = client.get("lb://example-server/").send().await.unwrap();
    }
    
    
  • discovery

    use discovery dynamic control the supplier elements, can send the elements change event insert,remove or initialized to the stream.

    
    use reqwest::{Client, Url};
    use reqwest_lb::discovery::Change;
    use reqwest_lb::supplier::DiscoverySupplier;
    use reqwest_lb::supplier::LoadBalancer;
    use reqwest_lb::LoadBalancerMiddleware;
    use reqwest_lb::LoadBalancerPolicy;
    use reqwest_lb::LoadBalancerRegistry;
    use reqwest_middleware::{ClientBuilder, ClientWithMiddleware};
    
    pub fn create<const N: usize>(
        ports: [u16; N],
        policy: LoadBalancerPolicy<Url>,
    ) -> ClientWithMiddleware {
        // create load balancer factory
        let mut registry = LoadBalancerRegistry::default();
        let mut events = ports
            .iter()
            .map(|port| {
                Url::parse(&format!("http://127.0.0.1:{}", port)).map(|url| Change::Insert(*port, url))
            })
            .collect::<Vec<_>>();
    
        // NOTICE: the initialized event notify load balancer all elements already insert
        events.push(Ok(Change::Initialized));
    
        let supplier = DiscoverySupplier::new(futures::stream::iter(events));
        let load_balancer = LoadBalancer::new(supplier, policy);
    
        registry.add("example-server", load_balancer);
    
        // create reqwest client
        let middleware = LoadBalancerMiddleware::new(registry);
        ClientBuilder::new(Client::builder().no_proxy().build().unwrap())
            .with(middleware)
            .build()
    }
    
    #[tokio::main]
    async fn main() {
        // use round robin policy
        let client = create([3001, 3002], LoadBalancerPolicy::RoundRobin);
        // http://127.0.0.1:3001
        let response = client.get("lb://example-server/").send().await.unwrap();
        // http://127.0.0.1:3002
        let response = client.get("lb://example-server/").send().await.unwrap();
    }
    
    
  • load balancer policy

    • RoundRobin (default)
    • Random
    • First
    • Last
    • Weight

License

This project is licensed under the Apache 2.0

Dependencies

~7–18MB
~232K SLoC