tonic_middleware/
middleware.rs

1use std::task::{Context, Poll};
2
3use crate::ServiceBound;
4use async_trait::async_trait;
5use futures_util::future::BoxFuture;
6use tonic::body::Body;
7use tonic::codegen::http::Request;
8use tonic::codegen::http::Response;
9use tonic::codegen::Service;
10use tonic::server::NamedService;
11use tower::Layer;
12
13/// The `Middleware` trait defines a generic interface for middleware components
14/// in a grpc service chain.
15/// Implementors of this trait can modify, observe, or otherwise interact with requests and
16/// responses in the service pipeline
17///
18/// If you need just intercept requests, pls can [RequestInterceptor]
19///
20/// # Type Parameters
21///
22/// * `S`: A service bound that defines the requirements for the service being wrapped by
23/// the middleware.
24///
25/// See [examples on GitHub](https://github.com/teimuraz/tonic-middleware/tree/main/example)
26#[async_trait]
27pub trait Middleware<S>
28where
29    S: ServiceBound,
30{
31    /// Processes an incoming request and forwards it to the given service.
32    ///
33    /// Implementations may perform operations before or after forwarding the request,
34    /// such as logging, metrics collection, or request modification.
35    ///
36    /// # Parameters
37    ///
38    /// * `req`: The incoming request to process.
39    /// * `service`: The service to forward the processed request to.
40    ///
41    /// # Returns
42    ///
43    /// A `Result` containing the response from the service or an error if one occurred
44    /// during processing.
45    async fn call(&self, req: Request<Body>, service: S) -> Result<Response<Body>, S::Error>;
46}
47
48/// `MiddlewareFor` is a service wrapper that pairs a middleware with its target service.
49///
50/// # Type Parameters
51///
52/// * `S`: The service that this middleware is wrapping.
53/// * `M`: The middleware that is being applied to the service.
54#[derive(Clone)]
55pub struct MiddlewareFor<S, M>
56where
57    S: ServiceBound,
58    M: Middleware<S>,
59{
60    pub inner: S,
61    pub middleware: M,
62}
63
64impl<S, M> MiddlewareFor<S, M>
65where
66    S: ServiceBound,
67    M: Middleware<S>,
68{
69    /// Constructs a new `MiddlewareFor` with the given service and middleware.
70    ///
71    /// # Parameters
72    ///
73    /// * `inner`: The service that this middleware is wrapping.
74    /// * `middleware`: The middleware that is being applied to the service.
75    pub fn new(inner: S, middleware: M) -> Self {
76        MiddlewareFor { inner, middleware }
77    }
78}
79
80impl<S, M> Service<Request<Body>> for MiddlewareFor<S, M>
81where
82    S: ServiceBound,
83    S::Future: Send,
84    M: Middleware<S> + Send + Clone + 'static + Sync,
85{
86    type Response = S::Response;
87    type Error = S::Error;
88    type Future = BoxFuture<'static, Result<Self::Response, Self::Error>>;
89
90    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
91        self.inner.poll_ready(cx)
92    }
93
94    fn call(&mut self, req: Request<Body>) -> Self::Future {
95        let middleware = self.middleware.clone();
96        let inner = self.inner.clone();
97        Box::pin(async move { middleware.call(req, inner).await })
98    }
99}
100
101impl<S, M> NamedService for MiddlewareFor<S, M>
102where
103    S: NamedService + ServiceBound,
104    M: Middleware<S>,
105{
106    const NAME: &'static str = S::NAME;
107}
108
109/// `MiddlewareLayer` provides a way to wrap services with a specific middleware using
110/// the tower `Layer` trait
111#[derive(Clone)]
112pub struct MiddlewareLayer<M> {
113    middleware: M,
114}
115
116impl<M> MiddlewareLayer<M> {
117    /// Creates a new `MiddlewareLayer` with the given middleware.
118    ///
119    /// # Parameters
120    ///
121    /// * `middleware`: The middleware to apply to services.
122    pub fn new(middleware: M) -> Self {
123        MiddlewareLayer { middleware }
124    }
125}
126
127impl<S, M> Layer<S> for MiddlewareLayer<M>
128where
129    S: ServiceBound,
130    M: Middleware<S> + Clone,
131{
132    type Service = MiddlewareFor<S, M>;
133
134    fn layer(&self, inner: S) -> Self::Service {
135        MiddlewareFor::new(inner, self.middleware.clone())
136    }
137}
tonic_middleware/middleware.rs

tonic_middleware/
middleware.rs
