praxis-proxy-core 0.7.5

Configuration, error types, and server factory for Praxis
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// SPDX-License-Identifier: Apache-2.0
// Copyright (c) 2024 Praxis Contributors

#![forbid(unsafe_code)]
#![deny(unreachable_pub)]

//! Core configuration, error types, and server factory for Praxis.
//!
//! `praxis-core` is the leaf of the crate dependency flow
//! `server -> protocol -> filter -> core -> tls`: it depends only on
//! [`praxis_tls`] and is depended on by every other Praxis crate. It
//! exists to give the filter, protocol, and server layers a single
//! source of truth for what a valid proxy looks like, so a parsed
//! configuration can be treated as already well-formed downstream.
//!
//! Responsibilities:
//! - YAML configuration parsing and validation with serde ([`config`]).
//! - Error types shared across the workspace ([`errors`], re-exported as [`ProxyError`]).
//! - Health state for active health checking ([`health`]) and the key-value store trait and registry ([`kv`]).
//! - The network backend contract ([`server::ServerRuntime`], [`egress`]) with the build's selected backend behind
//!   [`backend`], the runtime options ([`RuntimeOptions`]) and tracing setup ([`TracingGuard`], [`logging`]).
//!
//! Configuration types validate at load time, upholding the invariant
//! that higher layers never re-check structural validity of a [`config`]
//! value they receive.

/// Circuit breaker state machine for sub-request fault isolation.
pub mod circuit;
/// YAML configuration parsing and validation.
pub mod config;
/// Upstream connection options and endpoint types.
pub mod connectivity;
/// Backend-neutral egress: peers, connectors, and sessions.
pub mod egress;
/// Error types shared across the workspace.
pub mod errors;
/// Process-wide file descriptor pressure monitoring.
pub mod fd;
/// Shared gRPC protocol utilities.
pub mod grpc;
/// Shared health state types for active health checking.
pub mod health;
/// Hedge-copy admission budget and the per-request race.
pub mod hedge;
/// Per-instance request ID generation.
pub mod id;
/// Key-value store trait and registry.
pub mod kv;
/// Tracing subscriber setup.
pub mod logging;
/// Process-wide memory pressure monitoring.
pub mod memory;
/// Hop-by-hop and reserved-header stripping for the next HTTP hop.
pub mod next_hop_headers;
/// Reserved internal header prefixes for proxy-internal metadata.
pub mod reserved_headers;
/// Shared retry budget and per-cluster active-request tracking.
pub mod retry;
/// Server factory and runtime options.
pub mod server;
/// Shared HTTP connector for sub-request execution.
pub mod subrequest;
/// Wall-clock time abstraction for filters.
pub mod time;
/// W3C trace-context extraction and injection when the `otel` feature is enabled.
#[cfg(feature = "otel")]
pub mod trace_context;
/// Shared W3C `tracestate` validation and normalization.
pub mod trace_state;

pub use errors::ProxyError;
pub use logging::TracingGuard;
#[cfg(feature = "pingora")]
pub use server::PingoraServerRuntime;
pub use server::{RuntimeOptions, ServerRuntime};

// -----------------------------------------------------------------------------
// Backend Selection
// -----------------------------------------------------------------------------

/// The network backend this build runs on.
///
/// Exactly one backend is selected at build time with a Cargo feature, and
/// these names resolve to its types: `Runtime` implements [`ServerRuntime`]
/// and `Connector` implements [`egress::Connector`]. Under the `pingora`
/// feature both are the Pingora implementations. Without a backend feature
/// the library still compiles: `Connector` refuses every connection and
/// `Runtime` has nothing to serve, and the `praxis-proxy` binary refuses to
/// build. Adding a backend means adding its feature here; see
/// `docs/developing/adding-backends.md`.
///
/// ```
/// use praxis_core::{backend, egress::Connector as _};
/// praxis_tls::provider::install(); // required before any connector is built
///
/// let connector = backend::Connector::new(16);
/// let _shared = connector.clone();
/// ```
///
/// [`ServerRuntime`]: crate::server::ServerRuntime
/// [`egress::Connector`]: crate::egress::Connector
pub mod backend {
    /// With no backend compiled in, every connection is refused.
    #[cfg(not(feature = "pingora"))]
    pub use crate::egress::Unavailable as Connector;
    /// The egress connector shared by every outbound exchange.
    #[cfg(feature = "pingora")]
    pub use crate::egress::pingora::PingoraConnector as Connector;
    /// With no backend compiled in, there is nothing to serve.
    #[cfg(not(feature = "pingora"))]
    pub use crate::server::UnavailableRuntime as Runtime;
    /// The server runtime: owns the async runtime, listeners and shutdown.
    #[cfg(feature = "pingora")]
    pub use crate::server::pingora::PingoraServerRuntime as Runtime;
}