Force namespace via cmdline parameter (#53)

* Force name via cmdline parameter

* Use a library to parse CLI flags

* Use less env vars

* Document it

main.go

@@ -1,7 +1,9 @@
 package main
 
 import (
+	"fmt"
 	"github.com/gin-gonic/gin"
+	"github.com/jessevdk/go-flags"
 	"github.com/komodorio/helm-dashboard/pkg/dashboard"
 	"github.com/pkg/browser"
 	log "github.com/sirupsen/logrus"
@@ -14,37 +16,70 @@ var (
 	date    = "unknown"
 )
 
+type options struct {
+	Verbose   bool `short:"v" long:"verbose" description:"Show verbose debug information"`
+	NoBrowser bool `short:"b" long:"no-browser" description:"Do not attempt to open Web browser upon start"`
+	Version   bool `long:"version" description:"Show tool version"`
+
+	Port uint `short:"p" long:"port" description:"Port to start server on" default:"8080"` // TODO: better default port to clash less?
+
+	Namespace string `short:"n" long:"namespace" description:"Limit operations to a specific namespace"`
+}
+
 func main() {
-	setupLogging()
+	opts := parseFlags()
 
-	// TODO: proper command-line parsing
-	if len(os.Args) > 1 { // dirty thing to allow --help to work
-		os.Exit(0)
-	}
+	setupLogging(opts.Verbose)
 
-	address, webServerDone := dashboard.StartServer(version)
+	address, webServerDone := dashboard.StartServer(version, int(opts.Port), opts.Namespace, opts.Verbose)
 
-	if os.Getenv("HD_NOBROWSER") == "" {
+	if opts.NoBrowser {
+		log.Infof("Access web UI at: %s", address)
+	} else {
 		log.Infof("Opening web UI: %s", address)
 		err := browser.OpenURL(address)
 		if err != nil {
 			log.Warnf("Failed to open Web browser for URL: %s", err)
 		}
-	} else {
-		log.Infof("Access web UI at: %s", address)
 	}
 
 	<-webServerDone
 	log.Infof("Done.")
 }
 
-func setupLogging() {
-	if os.Getenv("DEBUG") == "" {
-		log.SetLevel(log.InfoLevel)
-		gin.SetMode(gin.ReleaseMode)
-	} else {
+func parseFlags() options {
+	opts := options{}
+	args, err := flags.Parse(&opts)
+	if err != nil {
+		if e, ok := err.(*flags.Error); ok {
+			if e.Type == flags.ErrHelp {
+				os.Exit(0)
+			}
+		}
+
+		// we rely on default behavior to print the problem inside `flags` library
+		os.Exit(1)
+	}
+
+	if opts.Version {
+		fmt.Print(version)
+		os.Exit(0)
+	}
+
+	if len(args) > 0 {
+		panic("The program does not take argumants, see --help for usage")
+	}
+	return opts
+}
+
+func setupLogging(verbose bool) {
+	if verbose {
 		log.SetLevel(log.DebugLevel)
 		gin.SetMode(gin.DebugMode)
+		log.Debugf("Debug logging is enabled")
+	} else {
+		log.SetLevel(log.InfoLevel)
+		gin.SetMode(gin.ReleaseMode)
 	}
 	log.Infof("Helm Dashboard by Komodor, version %s (%s @ %s)", version, commit, date)
 }