Fix buffer dead-lock in Watchdog (#33)

* Go sync group to handle blocking on buffered-pipes

watchdog/main.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"os/exec"
 	"strings"
+	"sync"
 	"time"
 )
 
@@ -20,21 +21,34 @@ func (OsEnv) Getenv(key string) string {
 	return os.Getenv(key)
 }
 
-func makeRequestHandler(config *WatchdogConfig) func(http.ResponseWriter, *http.Request) {
-	return func(w http.ResponseWriter, r *http.Request) {
-		if r.Method == "POST" {
+func pipeRequest(config *WatchdogConfig, w http.ResponseWriter, r *http.Request) {
 	parts := strings.Split(config.faasProcess, " ")
 
 	targetCmd := exec.Command(parts[0], parts[1:]...)
 	writer, _ := targetCmd.StdinPipe()
 
-			res, _ := ioutil.ReadAll(r.Body)
+	var out []byte
+	var err error
+	var res []byte
+
+	var wg sync.WaitGroup
+	wg.Add(2)
+
+	res, _ = ioutil.ReadAll(r.Body)
 	defer r.Body.Close()
 
+	go func() {
+		defer wg.Done()
 		writer.Write(res)
 		writer.Close()
+	}()
 
-			out, err := targetCmd.CombinedOutput()
+	go func() {
+		defer wg.Done()
+		out, err = targetCmd.CombinedOutput()
+	}()
+
+	wg.Wait()
 
 	if err != nil {
 		if config.writeDebug == true {
@@ -56,6 +70,12 @@ func makeRequestHandler(config *WatchdogConfig) func(http.ResponseWriter, *http.
 	}
 	w.WriteHeader(200)
 	w.Write(out)
+}
+
+func makeRequestHandler(config *WatchdogConfig) func(http.ResponseWriter, *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if r.Method == "POST" {
+			pipeRequest(config, w, r)
 		} else {
 			w.WriteHeader(http.StatusMethodNotAllowed)
 		}