piper

piper is a small library to aide in running a process locally, but actually run it remotely over a WebSocket connection.

Here is an example of its usage in a tool used on Gondor:

package main

import (
	"flag"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/exec"
	"strings"

	"github.com/eldarion-gondor/piper"
	"github.com/gorilla/websocket"
)

var secret = flag.String("secret", "", "")
var buildSHA string

var upgrader = websocket.Upgrader{
	ReadBufferSize:  8192,
	WriteBufferSize: 8192,
}

func main() {
	flag.Parse()
	if len(flag.Args()) == 0 {
		fmt.Println("no program to exec")
		os.Exit(1)
	}
	done := make(chan bool)
	http.HandleFunc("/ok", func(rw http.ResponseWriter, req *http.Request) {
		rw.WriteHeader(http.StatusOK)
	})
	http.HandleFunc("/", func(rw http.ResponseWriter, req *http.Request) {
		defer func() { done <- true }()
		log.Println("connection recieved")
		ws, err := upgrader.Upgrade(rw, req, nil)
		if err != nil {
			log.Printf("upgrade error: %s", err)
			return
		}
		log.Println("upgraded to websockets; ready to pipe")
		pipe, err := piper.NewServerPipe(req, ws)
		if err != nil {
			log.Printf("pipe error: %s", err)
			ws.Close()
			return
		}
		log.Printf("exec: %s", strings.Join(flag.Args(), " "))
		cmd := exec.Command(flag.Arg(0), flag.Args()[1:]...)
		if err := pipe.RunCmd(cmd); err != nil {
			log.Printf("exec error: %s", err)
			pipe.Close("error")
			return
		}
	})
	go func() {
		if err := http.ListenAndServe(":8000", nil); err != nil {
			fmt.Println(err)
			os.Exit(1)
		}
	}()
	<-done
}

This program will start an HTTP server and expose a process via a WebSocket connection.