Middleware layers for Pingora’s ProxyHttp trait.

Pingora’s ProxyHttp trait has ~40 methods and no built-in middleware or layer system. A single monolithic impl handles all concerns. Concerns that span multiple phases (e.g. auth touches request_filter, upstream_request_filter, and logging) are split across methods shared with unrelated logic.

Wrapping one ProxyHttp in another keeps each concern in one impl, but requires forwarding ~34 default methods. This crate generates them:

#[proxy_http_delegate(self.inner)]
impl<T: ProxyHttp> ProxyHttp for MyLayer<T> { ... }

#[proxy_http_delegate]

Generates self.<inner>.method(...) delegations for every ProxyHttp method not already defined in the impl block.

Also emits #[async_trait] and #[deny(clippy::missing_trait_methods)] on the impl — do not add these yourself.

Syntax

#[proxy_http_delegate(self.inner)]                  // lint defaults to deny
#[proxy_http_delegate(self.inner, lint = warn)]     // downgrade to warning
#[proxy_http_delegate(self.inner, lint = allow)]    // silence the lint
#[proxy_http_delegate(self.inner, lint = deny)]     // explicit deny (default)
#[proxy_http_delegate(self.inner, ctx = ctx.inner)] // map context for delegation

The lint option controls the clippy::missing_trait_methods lint level emitted on the impl block. It accepts deny (default), warn, or allow.

The ctx option remaps the context passed to the inner delegate. When set, delegation calls pass the mapped expression (e.g. &mut ctx.inner) instead of ctx directly. The new_ctx delegation is not generated — you must define it yourself. This is useful when your layer has its own context type that wraps the inner context.

Example

use pingora_core::prelude::*;
use pingora_proxy::{ProxyHttp, Session};
use pingora_proxy_delegate::proxy_http_delegate;

struct InnerProxy;

#[async_trait::async_trait]
impl ProxyHttp for InnerProxy {
    type CTX = ();

    fn new_ctx(&self) -> Self::CTX {
        todo!()
    }
    async fn upstream_peer(
        &self,
        _: &mut pingora_proxy::Session,
        _: &mut Self::CTX,
    ) -> Result<Box<HttpPeer>, Box<pingora_core::Error>> {
        todo!()
    }
}

struct MyDecorator<Inner> {
    inner: Inner,
}

#[proxy_http_delegate(self.inner)]
impl<Inner> ProxyHttp for MyDecorator<Inner>
where
    Inner: ProxyHttp + Send + Sync,
    Inner::CTX: Default + Send + Sync + 'static,
{
    type CTX = Inner::CTX;

    async fn logging(
        &self,
        session: &mut Session,
        error: Option<&pingora_core::Error>,
        ctx: &mut Self::CTX,
    ) where
        Self::CTX: Send + Sync,
    {
        self.inner.logging(session, error, ctx).await;
        // your logic here
    }
}

Layers nest: MyDecorator<AuthLayer<RateLimitLayer<CoreProxy>>>.

Compatibility

Targets Pingora 0.8. If Pingora adds a new trait method the missing_trait_methods deny will surface a compile error — update this crate’s method list and re-release.