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

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

README.md