dn42grcsrv/dn42grcsrv.go

//////////////////////////////////////////////////////////////////////////
// DN42 GRC API Server
//////////////////////////////////////////////////////////////////////////

package main

//////////////////////////////////////////////////////////////////////////

import (
	"context"
	"github.com/gorilla/mux"
	log "github.com/sirupsen/logrus"
	flag "github.com/spf13/pflag"
	"net/http"
	"os"
	"os/signal"
	"time"
)

//////////////////////////////////////////////////////////////////////////

var EventBus = make(SimpleEventBus)

//////////////////////////////////////////////////////////////////////////
// http request logger

func requestLogger(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

		log.WithFields(log.Fields{
			"method": r.Method,
			"URL":    r.URL.String(),
			"Remote": r.RemoteAddr,
		}).Debug("HTTP Request")

		next.ServeHTTP(w, r)
	})
}

//////////////////////////////////////////////////////////////////////////
// Install static routes

func installStaticRoutes(router *mux.Router, staticPath string) {

	// an empty path disables static route serving
	if staticPath == "" {
		log.Info("Disabling static route serving")
		return
	}

	// validate that the staticPath exists
	stat, err := os.Stat(staticPath)
	if err != nil {
		log.WithFields(log.Fields{
			"error": err,
			"path":  staticPath,
		}).Fatal("Unable to find static page directory")
	}

	// and it is a directory
	if !stat.IsDir() {
		log.WithFields(log.Fields{
			"error": err,
			"path":  staticPath,
		}).Fatal("Static path is not a directory")
	}

	// install a file server for the static route
	router.PathPrefix("/").Handler(http.StripPrefix("/",
		http.FileServer(http.Dir(staticPath)))).Methods("GET")

	log.WithFields(log.Fields{
		"path": staticPath,
	}).Info("Static route installed")

}

//////////////////////////////////////////////////////////////////////////
// everything starts here

func main() {

	// set a default log level, so that logging can be used immediately
	// the level will be overidden later on once the command line
	// options are loaded
	log.SetLevel(log.InfoLevel)
	log.Info("DN42 GRC API Server Starting")

	// declare cmd line options
	var (
		logLevel        = flag.StringP("LogLevel", "l", "Info", "Log level")
		bindAddress     = flag.StringP("BindAddress", "b", ":80", "Server bind address")
		staticRoot      = flag.StringP("StaticRoot", "s", "/home/grcsrv/webapp", "Static page directory")
		refreshInterval = flag.StringP("Refresh", "i", "60m", "Refresh interval")
	)
	flag.Parse()

	// now initialise logging properly based on the cmd line options
	setLogLevel(*logLevel)

	// parse the refreshInterval and start data collection
	interval, err := time.ParseDuration(*refreshInterval)
	if err != nil {
		log.WithFields(log.Fields{
			"error":    err,
			"interval": *refreshInterval,
		}).Fatal("Unable to parse registry refresh interval")
	}

	interval = interval

	// start data collection here

	// initialise router
	router := mux.NewRouter()
	// log all access
	router.Use(requestLogger)

	// add API routes
	subr := router.PathPrefix("/api").Subrouter()
	EventBus.Fire("APIEndpoint", subr)

	// initialise static routes
	installStaticRoutes(router, *staticRoot)

	// initialise http server
	server := &http.Server{
		Addr:         *bindAddress,
		WriteTimeout: time.Second * 15,
		ReadTimeout:  time.Second * 15,
		IdleTimeout:  time.Second * 60,
		Handler:      router,
	}

	// run the server in a non-blocking goroutine

	log.WithFields(log.Fields{
		"BindAddress": *bindAddress,
	}).Info("Starting server")

	go func() {
		if err := server.ListenAndServe(); err != nil {
			log.WithFields(log.Fields{
				"error":       err,
				"BindAddress": *bindAddress,
			}).Fatal("Unable to start server")
		}
	}()

	// graceful shutdown via SIGINT (^C)
	csig := make(chan os.Signal, 1)
	signal.Notify(csig, os.Interrupt)

	// and block
	<-csig

	log.Info("Server shutting down")

	// deadline for server to shutdown
	ctx, cancel := context.WithTimeout(context.Background(), 10)
	defer cancel()

	// shutdown the server
	server.Shutdown(ctx)

	// nothing left to do
	log.Info("Shutdown complete, all done")
	os.Exit(0)
}

//////////////////////////////////////////////////////////////////////////
// end of code