ping web

pingweb.go

package main

import (
	"encoding/json"
	"io"
	"log"
	"net/http"
	"os"
	"os/signal"
)

// These have to be upper case if we want to marshal with json.

type Service struct {
	Name   string `json:"name"`
	Status string `json:"status"`
}

type Status struct {
	Summary  string    `json:"summary"`
	Services []Service `json:"services"`
}

func findStatus() Status {
	return Status{
		Summary: "Partial",
		Services: []Service{
			Service{"Foo", "Ok"},
			Service{"Bar", "Ok"},
			Service{"Baz", "Down"}}}
}

func jsonWrite(d interface{}) string {
	b, err := json.MarshalIndent(d, "", "  ")
	if err != nil {
		panic(err)
	}
	return string(b)
}

func pingHandler(w http.ResponseWriter, r *http.Request) {
	io.WriteString(w, "Ok")
}

func statusHandler(w http.ResponseWriter, r *http.Request) {
	b := jsonWrite(findStatus())
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(200)
	io.WriteString(w, b)
}

func start() {
	log.Println("Starting web app.")
	log.Fatal(http.ListenAndServe(":8080", nil))
}

func lock() {
	log.Println("Setting up signal listener.")
	var sigChan = make(chan os.Signal, 1)

	signal.Notify(sigChan, os.Interrupt)
	whatSig := <-sigChan

	log.Printf("System signal: `%s`.\n", whatSig)
}

func main() {

	log.Println("Hello Ping Web Application")

	http.HandleFunc("/ping", pingHandler)
	http.HandleFunc("/status", statusHandler)

	go start()

	log.Println("Locking...")
	lock()
	log.Println("System halt.")
}