reverseproxy

Enhanced HTTP reverse proxy with WebSocket and HTTP/2 support, integrated with godoxy's logging and access control systems.

Overview

This package extends Go's net/http/httputil/reverse_proxy with:

• Integrated logging: Uses godoxy's zerolog logger for structured logging
• Access logging: Built-in support for accesslog.AccessLogger
• Scheme mismatch handling: Custom callback for HTTP/HTTPS scheme mismatches
• Enhanced header manipulation: X-Forwarded headers, WebSocket header normalization
• HTTP/2 h2c support: Cleartext HTTP/2 support
• Error suppression: Suppresses certain unimportant/expected errors to prevent logging them
• Performance optimizations: Uses CopyCloseContext with sync.Pool for efficient body copying, reducing GC pressure

Key Differences from stdlib

Feature	stdlib httputil/reverse_proxy	This Package
Logging	log.Printf	zerolog.Logger
Access logging	Not supported	AccessLogger interface
Scheme mismatch	Not supported	OnSchemeMisMatch callback
X-Forwarded headers	Manual via Director	Built-in SetXForwarded()
WebSocket headers	Basic handling	Normalized casing
Body copy	io.Copy	CopyCloseContext with buffer pool

Integration with GoDoxy

import (
    "github.com/yusing/godoxy/goutils/http/reverseproxy"
    "github.com/yusing/godoxy/internal/logging"
)

// Create proxy with godoxy's logger
rp := reverseproxy.NewReverseProxy("backend", target, nil)
rp.Logger = logging.Logger  // Uses godoxy's zerolog logger
rp.AccessLogger = logging.AccessLogger  // Uses godoxy's access logging

API Reference

ReverseProxy

type ReverseProxy struct {
    zerolog.Logger  // Embedded for structured logging
    Transport http.RoundTripper
    ModifyResponse func(*http.Response) error
    AccessLogger accesslog.AccessLogger
    HandlerFunc http.HandlerFunc
    OnSchemeMisMatch func() bool  // Called on HTTP/HTTPS scheme mismatch
    TargetName string
    TargetURL *url.URL
}

ProxyRequest

type ProxyRequest struct {
    In *http.Request   // Incoming request (read-only)
    Out *http.Request  // Outgoing request (modifiable)
}

Functions

NewReverseProxy

func NewReverseProxy(name string, target *url.URL, transport http.RoundTripper) *ReverseProxy

Creates a proxy. Transport can be nil to use default.

SetXForwarded

func (p *ProxyRequest) SetXForwarded()

Sets all X-Forwarded headers (For, Host, Proto, Method, URI, Port) on the outbound request.

Handler

func (p *ReverseProxy) ServeHTTP(rw http.ResponseWriter, req *http.Request)

Main request handler with automatic:

• Hop-by-hop header removal
• X-Forwarded header setting
• WebSocket upgrade handling
• Response modification

Usage Examples

Basic Setup

target, _ := url.Parse("http://localhost:8080")
rp := reverseproxy.NewReverseProxy("backend", target, nil)
http.Handle("/", rp)

With GoDoxy Logging

import "github.com/yusing/godoxy/internal/logging"

rp := reverseproxy.NewReverseProxy("backend", target, nil)
rp.Logger = logging.With().Str("component", "reverse_proxy").Logger()

With Scheme Mismatch Detection

rp := reverseproxy.NewReverseProxy("backend", target, nil)
rp.OnSchemeMisMatch = func() bool {
    rp.Logger.Warn().Msg("Scheme mismatch detected")
    return true  // Retry with different scheme
}

Custom Request Rewrite

rewriteFunc := func(pr *reverseproxy.ProxyRequest) {
    pr.SetXForwarded()
    pr.Out.URL.Path = strings.TrimPrefix(pr.Out.URL.Path, "/api")
}

Performance

• Buffer pooling: Uses CopyCloseContext with sync.Pool for efficient body copying, reducing GC pressure

• Context propagation: Properly handles request cancellation via context

• HTTP/1.1: Full support

• HTTP/2: h2c cleartext support

• WebSocket: Automatic upgrade handling with header normalization

Header Handling

1. Removes hop-by-hop headers: Connection, Transfer-Encoding, Upgrade, etc.
2. Sets X-Forwarded headers automatically
3. Removes service headers: X-Powered-By, Server
4. Normalizes WebSocket header casing

Related Packages

• accesslog - Access logging interface
• httpheaders - Header manipulation utilities
• websocket - WebSocket utilities