proxy for metabase to run behind IIS

main.go

package main

import (
	"fmt"
	"log"
	"net/http"
	"net/http/httputil"
	"os"
	"os/exec"
	"time"
)

func main() {
	err := startMetabase()
	if err != nil {
		log.Panicf("could not start metabase %s", err.Error())
	}
	proxy := setupProxy()
	http.Handle("/", proxy)

	fmt.Println("Listening at " + os.Getenv("HTTP_PLATFORM_PORT"))
	log.Fatal(http.ListenAndServe("localhost:"+os.Getenv("HTTP_PLATFORM_PORT"), nil))
}

func startMetabase() error {
	cmd := exec.Command("java.exe", "-jar", ".\\metabase.jar")
	cmd.Stderr = os.Stderr
	cmd.Stdout = os.Stdout
	return cmd.Start()
}

func setupProxy() *httputil.ReverseProxy {
	metabasePort := os.Getenv("MB_JETTY_PORT")
	director := func(req *http.Request) {
		waitReady()

		req.URL.Scheme = "http"
		req.URL.Host = "localhost:" + metabasePort
		req.Host = req.URL.Host
	}
	return &httputil.ReverseProxy{Director: director}
}

var metabaseReady = false

func waitReady() {
	for !metabaseReady {
		metabasePort := os.Getenv("MB_JETTY_PORT")
		resp, err := http.Get("http://localhost:" + metabasePort)
		if err == nil && resp.StatusCode >= 200 && resp.StatusCode < 400 {
			metabaseReady = true
		} else {
			time.Sleep(300 * time.Millisecond)
		}
	}
}