From d3c4f85c8ec93b9b739abfb4629ef2dce633b8e1 Mon Sep 17 00:00:00 2001
From: Vishal Thapar <5137689+vthapar@users.noreply.github.com>
Date: Tue, 25 Jul 2023 18:00:48 +0530
Subject: [PATCH] Add version flag to LH binaries

Adds `--version` flag to Lighthouse Agent and `--subm-version`
flag to Lighthouse Coredns. CoreDNS already has `--version` which
prints CoreDNS version, so we can't use the same flag for
Lighthouse version.

Removed a log entry from metrics.go which didn't add much value
so we can have version as first entry in log file.

Refer https://github.com/submariner-io/enhancements/pull/204

Fixes #1333

Signed-off-by: Vishal Thapar <5137689+vthapar@users.noreply.github.com>
---
 coredns/main.go           | 20 +++++++++++++++++---
 coredns/plugin/metrics.go |  2 --
 coredns/plugin/setup.go   |  3 ---
 pkg/agent/main.go         | 22 +++++++++++++++-------
 4 files changed, 32 insertions(+), 15 deletions(-)

diff --git a/coredns/main.go b/coredns/main.go
index c57505309..99d36ec25 100644
--- a/coredns/main.go
+++ b/coredns/main.go
@@ -22,6 +22,10 @@ package main
 // https://coredns.io/2017/07/25/compile-time-enabling-or-disabling-plugins/#build-with-external-golang-source-code
 
 import (
+	"flag"
+	"fmt"
+	"os"
+
 	_ "github.com/coredns/caddy/onevent"
 	"github.com/coredns/coredns/core/dnsserver"
 	"github.com/coredns/coredns/coremain"
@@ -61,7 +65,7 @@ import (
 	_ "github.com/coredns/coredns/plugin/tls"
 	_ "github.com/coredns/coredns/plugin/trace"
 	_ "github.com/coredns/coredns/plugin/whoami"
-	lighthouse "github.com/submariner-io/lighthouse/coredns/plugin"
+	_ "github.com/submariner-io/lighthouse/coredns/plugin"
 )
 
 var directives = []string{
@@ -105,13 +109,23 @@ var directives = []string{
 	"on",
 }
 
-var version = "not-compiled-properly"
+var (
+	version     = "not-compiled-properly"
+	showVersion = false
+)
 
 func init() {
-	lighthouse.Version = version
+	flag.BoolVar(&showVersion, "subm-version", showVersion, "Show version")
 	dnsserver.Directives = directives
 }
 
 func main() {
+	flag.Parse()
+	fmt.Fprintf(os.Stderr, "submariner-lighthouse-coredns version: %s\n", version)
+
+	if showVersion {
+		return
+	}
+
 	coremain.Run()
 }
diff --git a/coredns/plugin/metrics.go b/coredns/plugin/metrics.go
index 301634023..68558dafb 100644
--- a/coredns/plugin/metrics.go
+++ b/coredns/plugin/metrics.go
@@ -35,8 +35,6 @@ const (
 var dnsQueryCounter *prometheus.GaugeVec
 
 func init() {
-	log.Infof("Initializing dns query counter")
-
 	dnsQueryCounter = prometheus.NewGaugeVec(
 		prometheus.GaugeOpts{
 			Name: ServiceDiscoveryQueryCounterName,
diff --git a/coredns/plugin/setup.go b/coredns/plugin/setup.go
index b081e4aec..2d99a7fa3 100644
--- a/coredns/plugin/setup.go
+++ b/coredns/plugin/setup.go
@@ -42,7 +42,6 @@ import (
 var (
 	masterURL  string
 	kubeconfig string
-	Version    string
 )
 
 // Hooks for unit tests.
@@ -71,8 +70,6 @@ func init() {
 // setup is the function that gets called when the config parser see the token "lighthouse". Setup is responsible
 // for parsing any extra options the this plugin may have. The first token this function sees is "lighthouse".
 func setupLighthouse(c *caddy.Controller) error {
-	log.Infof("submariner-lighthouse-coredns version: %v", Version)
-
 	l, err := lighthouseParse(c)
 	if err != nil {
 		return plugin.Error(PluginName, err) //nolint:wrapcheck // No need to wrap this.
diff --git a/pkg/agent/main.go b/pkg/agent/main.go
index 00a48d226..5aa46807d 100644
--- a/pkg/agent/main.go
+++ b/pkg/agent/main.go
@@ -43,16 +43,20 @@ import (
 	mcsv1a1 "sigs.k8s.io/mcs-api/pkg/apis/v1alpha1"
 )
 
+const componentName = "submariner-lighthouse-agent"
+
 var (
-	masterURL  string
-	kubeConfig string
-	help       = false
-	logger     = log.Logger{Logger: logf.Log.WithName("main")}
-	version    = "not-compiled-properly"
+	masterURL   string
+	kubeConfig  string
+	help        = false
+	showVersion = false
+	logger      = log.Logger{Logger: logf.Log.WithName("main")}
+	version     = "not-compiled-properly"
 )
 
 func init() {
 	flag.BoolVar(&help, "help", help, "Print usage options")
+	flag.BoolVar(&showVersion, "version", showVersion, "Show version")
 }
 
 func exitOnError(err error, reason string) {
@@ -84,6 +88,12 @@ func main() {
 		return
 	}
 
+	fmt.Fprintf(os.Stderr, "%s version: %s\n", componentName, version)
+
+	if showVersion {
+		return
+	}
+
 	kzerolog.InitK8sLogging()
 
 	// initialize klog as well, since some internal k8s packages still log with klog directly
@@ -112,8 +122,6 @@ func main() {
 	localClient, err := dynamic.NewForConfig(cfg)
 	exitOnError(err, "Error creating dynamic client")
 
-	logger.Infof("submariner-lighthouse-agent version: %v", version)
-
 	// set up signals so we handle the first shutdown signal gracefully
 	ctx := signals.SetupSignalHandler()