main.go

package main

import (
	"fmt"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/Sirupsen/logrus"
	"github.com/pkg/errors"
	"github.com/urfave/cli"

	"github.com/longhorn/upgrade-responder/upgraderesponder"
)

var VERSION = "v0.0.0-dev"

const (
	FlagUpgradeResponseConfiguration = "upgrade-response-config"
	EnvUpgradeResponseConfiguration  = "UPGRADE_RESPONSE_CONFIG"
	FlagApplicationName              = "application-name"
	EnvApplicationName               = "APPLICATION_NAME"
	FlagInfluxDBURL                  = "influxdb-url"
	EnvInfluxDBURL                   = "INFLUXDB_URL"
	FlagInfluxDBUser                 = "influxdb-user"
	EnvInfluxDBUser                  = "INFLUXDB_USER"
	FlagInfluxDBPass                 = "influxdb-pass"
	EnvInfluxDBPass                  = "INFLUXDB_PASS"
	FlagQueryPeriod                  = "query-period"
	EnvQueryPeriod                   = "QUERY_PERIOD"
	FlagGeoDB                        = "geodb"
	EnvGeoDB                         = "GEODB"
	FlagPort                         = "port"
	EnvPort                          = "PORT"
)

func main() {
	app := cli.NewApp()
	app.Name = "upgrade-responder"
	app.Version = VERSION
	app.Flags = []cli.Flag{
		cli.BoolFlag{
			Name:   "debug, d",
			Usage:  "enable debug logging level",
			EnvVar: "DEBUG",
		},
	}
	app.Before = func(c *cli.Context) error {
		if c.GlobalBool("debug") {
			logrus.SetLevel(logrus.DebugLevel)
		}
		return nil
	}

	app.Commands = []cli.Command{
		UpgradeResponderCmd(),
	}

	if err := app.Run(os.Args); err != nil {
		logrus.Fatal(err)
	}
}

func UpgradeResponderCmd() cli.Command {
	return cli.Command{
		Name: "start",
		Flags: []cli.Flag{
			cli.StringFlag{
				Name:   FlagUpgradeResponseConfiguration,
				EnvVar: EnvUpgradeResponseConfiguration,
				Usage:  "Specify the response configuration file for upgrade query",
			},
			cli.StringFlag{
				Name:   FlagApplicationName,
				EnvVar: EnvApplicationName,
				Usage:  "Specify the name of the application that is using this upgrade checker. This will be used to create a database name <application-name>_upgrade_responder in the InfluxDB to store all data for this upgrade checker",
			},
			cli.StringFlag{
				Name:   FlagInfluxDBURL,
				EnvVar: EnvInfluxDBURL,
				Usage:  "Specify the URL of InfluxDB",
			},
			cli.StringFlag{
				Name:   FlagInfluxDBUser,
				EnvVar: EnvInfluxDBUser,
				Usage:  "Specify the InfluxDB user name",
			},
			cli.StringFlag{
				Name:   FlagInfluxDBPass,
				EnvVar: EnvInfluxDBPass,
				Usage:  "Specify the InfluxDB password",
			},
			cli.StringFlag{
				Name:   FlagQueryPeriod,
				EnvVar: EnvQueryPeriod,
				Value:  "1h",
				Usage:  "Specify the period for how often each instance of the application makes the request. Cannot change after set for the first time. This value should be the same as time in GROUP BY clause in Grafana",
			},
			cli.StringFlag{
				Name:   FlagGeoDB,
				EnvVar: EnvGeoDB,
				Usage:  "Specify the path of to GeoDB file",
			},
			cli.IntFlag{
				Name:   FlagPort,
				EnvVar: EnvPort,
				Value:  8314,
				Usage:  "Specify the port number",
			},
		},
		Action: func(c *cli.Context) error {
			return startUpgradeResponder(c)
		},
	}
}

func startUpgradeResponder(c *cli.Context) error {
	if err := validateCommandLineArguments(c); err != nil {
		return err
	}

	cfg := c.String(FlagUpgradeResponseConfiguration)
	influxURL := c.String(FlagInfluxDBURL)
	influxUser := c.String(FlagInfluxDBUser)
	influxPass := c.String(FlagInfluxDBPass)
	queryPeriod := c.String(FlagQueryPeriod)
	applicationName := c.String(FlagApplicationName)
	geodb := c.String(FlagGeoDB)
	port := c.Int(FlagPort)

	done := make(chan struct{})
	server, err := upgraderesponder.NewServer(done, applicationName, cfg, influxURL, influxUser, influxPass, queryPeriod, geodb)
	if err != nil {
		return err
	}
	router := http.Handler(upgraderesponder.NewRouter(server))

	listeningAddress := fmt.Sprintf("0.0.0.0:%v", port)

	go func() {
		logrus.Infof("Server is listening at %v", listeningAddress)
		// always returns error. ErrServerClosed on graceful close
		if err := http.ListenAndServe(listeningAddress, router); err != http.ErrServerClosed {
			logrus.Fatalf("%v", err)
		}
		<-done
	}()

	RegisterShutdownChannel(done)
	<-done
	return nil
}

func RegisterShutdownChannel(done chan struct{}) {
	sigs := make(chan os.Signal, 1)
	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
	go func() {
		sig := <-sigs
		logrus.Infof("Receive %v to exit", sig)
		close(done)
	}()
}

func validateCommandLineArguments(c *cli.Context) error {
	cfg := c.String(FlagUpgradeResponseConfiguration)
	if cfg == "" {
		return fmt.Errorf("no upgrade response configuration file specified")
	}

	applicationName := c.String(FlagApplicationName)
	if applicationName == "" {
		return fmt.Errorf("no application name specified")
	}

	queryPeriod := c.String(FlagQueryPeriod)
	if _, err := time.ParseDuration(queryPeriod); err != nil {
		return errors.Wrap(err, "fail to parse --query-period")
	}

	return nil
}