Socket Proxy Reverse Proxy

This package provides an HTTP reverse proxy implementation for proxying requests to Unix sockets (typically Docker sockets). It is based on Go's net/http/httputil.ReverseProxy with simplifications for socket proxying use cases.

Differences from net/http/httputil.ReverseProxy

Feature	stdlib httputil.ReverseProxy	This package
Request modification	Director or Rewrite	Director only
Response modification	ModifyResponse hook	Not supported
Buffering	Uses io.Copy	Uses ioutils.CopyCloseWithContext
Flush support	Flush() method	Not exposed

Key Simplifications

1. Director only: Only the Director function is supported. The stdlib's Rewrite type and ModifyResponse hook are removed.

2. Context-aware body copying: Uses ioutils.CopyCloseWithContext which:

   • Respects request context for cancellation
   • Uses Content-Length for optimal copying when available
   • Properly handles trailer headers

3. No buffering: Unlike the stdlib which can buffer responses, this implementation streams directly to the client.

Usage

rp := &reverseproxy.ReverseProxy{
    Director: func(req *http.Request) {
        req.URL.Scheme = "http"
        req.URL.Host = "api.moby.localhost"
        req.RequestURI = req.URL.String()
    },
    Transport: &http.Transport{
        DialContext: func(ctx context.Context, _, _ string) (net.Conn, error) {
            return net.DialTimeout("unix", "/var/run/docker.sock", 5*time.Second)
        },
        DisableCompression: true,
    },
}

http.HandleFunc("/", rp.ServeHTTP)
http.ListenAndServe(":2375", nil)

Socket Proxy Integration

The socket proxy uses this package in socket-proxy/pkg/handler.go:

func dockerSocketHandler(socket string) http.HandlerFunc {
    rp := &reverseproxy.ReverseProxy{
        Director: func(req *http.Request) {
            req.URL.Scheme = "http"
            req.URL.Host = "api.moby.localhost"
            req.RequestURI = req.URL.String()
        },
        Transport: &http.Transport{
            DialContext: func(ctx context.Context, _, _ string) (net.Conn, error) {
                dialer := &net.Dialer{KeepAlive: 1 * time.Second}
                return dialer.DialContext(ctx, "unix", socket)
            },
            DisableCompression: true,
        },
    }
    return rp.ServeHTTP
}

License

This code is based on Go's net/http/httputil and is licensed under the BSD-style license found at the top of reverse_proxy.go.