urltocmd/main.go

package main

import (
	"encoding/json"
	"io"
	"net/http"
	"os"
	"os/exec"
	"sync"
	"time"

	"gitea.larvit.se/pwrpln/go_log"
	"github.com/joho/godotenv"
)

func main() {
	// Load ENV from .env file
	err := godotenv.Load()
	if err != nil {
		tmpLog := go_log.GetLog()
		tmpLog.Info("Failed to load .env file!")
	}

	// Setting up logger
	log := go_log.GetLog()
	log.MinLogLvl = go_log.LogLvlFromStr(os.Getenv("LOG_LEVEL"))
	loc, err := time.LoadLocation(os.Getenv("LOG_LOCATION"))
	if err != nil {
		panic(err)
	}
	log.TimeLocation = loc

	// Open the JSON file for reading
	log.Info("Reading URLs and CMDs from file", "urls.json path", os.Getenv("URLS_CMDS_JSON_PATH"))
	file, err := os.Open(os.Getenv("URLS_CMDS_JSON_PATH"))
	if err != nil {
		log.Error("Error opening URLs and CMDs JSON file", "err", err.Error())
		panic(err)
	}

	// Read the JSON data from the file
	jsonStr, err := io.ReadAll(file)
	if err != nil {
		log.Error("Error reading JSON string from file", "err", err.Error())
		panic(err)
	}
	file.Close()

	var urlsToCmds map[string]string
	err = json.Unmarshal([]byte(jsonStr), &urlsToCmds)
	if err != nil {
		log.Error("Error unmarshalling JSON", "err", err.Error)
		panic(err)
	}

	http.HandleFunc("/", func(res http.ResponseWriter, req *http.Request) {
		cmdStr, exists := urlsToCmds[req.URL.Path]

		if !exists {
			log.Verbose("Call to undefined URL", "URL", req.URL.Path)
			res.WriteHeader(404)
			res.Write([]byte("Not Found"))
			return
		}

		log.Verbose("Executing command", "cmdStr", cmdStr)

		// Set the response headers for SSE
		res.Header().Set("Content-Type", "text/event-stream")
		res.Header().Set("Cache-Control", "no-cache")
		res.Header().Set("Connection", "keep-alive")

		// Create the command
		cmd := exec.Command("/bin/sh", "-c", cmdStr)

		// Create a pipes to capture the command's output
		stdoutPipe, err := cmd.StdoutPipe()
		if err != nil {
			http.Error(res, "Internal Server Error", 500)
			log.Error("Could not create stdout pipe from command", "err", err.Error())
			return
		}
		stderrPipe, err := cmd.StderrPipe()
		if err != nil {
			http.Error(res, "Internal Server Error", 500)
			log.Error("Could not create stderr pipe from command", "err", err.Error())
			return
		}

		// Start the command
		err = cmd.Start()
		if err != nil {
			http.Error(res, "Internal Server Error", 500)
			log.Error("Could not start the command", "err", err.Error())
			return
		}

		defer cmd.Wait()
		defer stdoutPipe.Close()
		defer stderrPipe.Close()

		var wg sync.WaitGroup

		wg.Add(1)
		go func() {
			buf := make([]byte, 1024)
			for {
				n, err := stdoutPipe.Read(buf)
				if err == io.EOF {
					break
				}
				if err != nil {
					log.Error("Error reading stdout from command", "err", err.Error())
					break
				}
				log.Debug("std", "out", string(buf[:n]))
				res.Write(buf[:n])
				flusher, ok := res.(http.Flusher)
				if ok {
					flusher.Flush()
				}
			}
			wg.Done()
		}()

		wg.Add(1)
		go func() {
			buf := make([]byte, 1024)
			for {
				n, err := stderrPipe.Read(buf)
				if err == io.EOF {
					break
				}
				if err != nil {
					log.Error("Error reading stderr from command", "err", err.Error())
					break
				}
				log.Debug("std", "err", string(buf[:n]))
				res.Write([]byte("STDERR: "))
				res.Write(buf[:n])
				flusher, ok := res.(http.Flusher)
				if ok {
					flusher.Flush()
				}
			}
			wg.Done()
		}()

		wg.Wait()
	})

	log.Info("Starting web server", "PORT", os.Getenv("PORT"))
	err = http.ListenAndServe(":"+os.Getenv("PORT"), nil)
	if err != nil {
		log.Error("Web server crashed", "err", err.Error())
	}
}