Initial

watchdog/Dockerfile

+FROM alpine:edge
+
+COPY ./fwatchdog /usr/bin/fwatchdog
+ENV fprocess "cat -b"
+
+EXPOSE 8080
+CMD ["fwatchdog"]

watchdog/Dockerfile.build

+FROM golang:1.7.3
+RUN mkdir -p /go/src/fwatchdog
+COPY main.go /go/src/fwatchdog
+WORKDIR /go/src/fwatchdog
+RUN go get -d -v
+RUN go build

watchdog/build.sh

+#!/bin/bash
+
+docker build -t watchdog:latest . -f Dockerfile.build
+docker create --name buildoutput watchdog:latest
+docker cp buildoutput:/go/src/fwatchdog/fwatchdog ./
+docker rm buildoutput
+

watchdog/main.go

+package main
+
+import (
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"os/exec"
+	"strings"
+	"time"
+)
+
+func main() {
+	s := &http.Server{
+		Addr:           ":8080",
+		ReadTimeout:    2 * time.Second,
+		WriteTimeout:   2 * time.Second,
+		MaxHeaderBytes: 1 << 20,
+	}
+
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		if r.Method == "POST" {
+			process := os.Getenv("fprocess")
+			parts := strings.Split(process, " ")
+			targetCmd := exec.Command(parts[0], parts[1:]...)
+			writer, _ := targetCmd.StdinPipe()
+			res, _ := ioutil.ReadAll(r.Body)
+			writer.Write(res)
+			writer.Close()
+			out, err := targetCmd.Output()
+			if err != nil {
+				panic(err)
+			}
+
+			os.Stdout.Write(out)
+			w.Write(out)
+		}
+	})
+
+	log.Fatal(s.ListenAndServe())
+}
+