feat: add suppress_pre_request_error_log

docs/user_guide/phase.md

@@ -130,6 +130,13 @@ Every error that reaches `fail_to_proxy()` will be automatically logged in the e
 
 This callback returns a string which allows users to customize what info to dump in the error log to help track and debug the failures.
 
+### `suppress_pre_request_error_log()`
+This is also not a phase, but another callback.
+
+This callback is similar to `suppress_error_log()`, but it is invoked for downstream request read and parse failures before the per-request `CTX` is created. Because the request may not have been parsed successfully yet, it receives the downstream HTTP session directly instead of `Session` and `CTX`.
+
+Return `true` to suppress the error log.
+
 ### `suppress_error_log()`
 This is also not a phase, but another callback.
 

pingora-proxy/src/lib.rs

@@ -67,7 +67,6 @@ use pingora_core::protocols::http::subrequest::server::SubrequestHandle;
 use pingora_core::protocols::http::v1::client::HttpSession as HttpSessionV1;
 use pingora_core::protocols::http::v2::server::H2Options;
 use pingora_core::protocols::http::HttpTask;
-use pingora_core::protocols::http::ServerSession as HttpSession;
 use pingora_core::protocols::http::SERVER_NAME;
 use pingora_core::protocols::Stream;
 use pingora_core::protocols::{Digest, UniqueID};
@@ -89,6 +88,7 @@ pub mod subrequest;
 
 use subrequest::{BodyMode, Ctx as SubrequestCtx};
 
+pub use pingora_core::protocols::http::ServerSession as HttpSession;
 pub use proxy_cache::range_filter::{range_header_filter, MultiRangeInfo, RangeType};
 pub use proxy_purge::PurgeStatus;
 pub use proxy_trait::{FailToProxy, ProxyHttp};
@@ -234,7 +234,12 @@ where
             }
             Err(mut e) => {
                 e.as_down();
-                error!("Fail to proxy: {e}");
+                if !self
+                    .inner
+                    .suppress_pre_request_error_log(&downstream_session, &e)
+                {
+                    error!("Fail to proxy: {e}");
+                }
                 if matches!(e.etype, InvalidHTTPHeader) {
                     downstream_session
                         .respond_error(400)

pingora-proxy/src/proxy_trait.rs

@@ -505,6 +505,15 @@ pub trait ProxyHttp {
     ) {
     }
 
+    /// A value of true means that the log message will be suppressed. The default value is false.
+    ///
+    /// This callback is invoked for downstream request read or parse failures, before
+    /// [`Self::early_request_filter`] and before [`Self::CTX`] is created, so
+    /// implementations should not assume `session.req_header()` is available.
+    fn suppress_pre_request_error_log(&self, _session: &HttpSession, _error: &Error) -> bool {
+        false
+    }
+
     /// A value of true means that the log message will be suppressed. The default value is false.
     fn suppress_error_log(&self, _session: &Session, _ctx: &Self::CTX, _error: &Error) -> bool {
         false