Help dynamically adding services to a server #744

itmecho · 2021-08-14T22:31:46Z

itmecho
Aug 14, 2021

I'm trying to write a reusable wrapper to use across some microservices but I can't figure out how to add an unknown amount of services to a Server. This is a rough idea of the wrapper:

use std::{collections::HashMap, error::Error, net::SocketAddr};

use http::{Request, Response};
use tonic::{
    body::BoxBody,
    transport::{Body, NamedService},
};

pub struct Service<S> {
    servers: HashMap<SocketAddr, Vec<S>>,
}

impl<S> Service<S>
where
    S: tower::Service<Request<Body>, Response = Response<BoxBody>>
        + NamedService
        + Clone
        + Send
        + 'static,
    S::Future: Send + 'static,
    S::Error: Into<Box<dyn Error + Send + Sync>> + Send,
{
    pub fn builder() -> Self {
        Self {
            servers: HashMap::new(),
        }
    }

    pub fn with_server(mut self, addr: SocketAddr, server: S) -> Self {
        self.servers.entry(addr).or_default().push(server);
        self
    }

    pub fn run(self) -> Result<(), Box<dyn Error>> {
        let mut x = vec![];
        for (addr, services) in self.servers {
            let server = tonic::transport::Server::builder(); // <- Server
            for svc in services {
                server = server.add_service(svc); // Error here as add_service returns a Router, not a Server
            }
            x.push(server.serve(addr)); // Error again as you can't call serve on a Server
        }

        tokio::try_join!(futures::future::join_all(x))?; // Error due to the errors above
        Ok(())
    }
}