feat: add -version flag for printing version and build info

Closes #117

Author: fionera

magefile.go

@@ -61,8 +61,11 @@ func Build() error {
 	if arch == "" {
 		arch = runtime.GOARCH
 	}
-
-	if err := sh.RunWith(map[string]string{"GOARCH": arch}, "go", "build", "-o", "build/coraza-spoa"); err != nil {
+	gitVersion, _ := sh.Output("git", "describe", "--tags", "--always", "--dirty")
+	ldflags := fmt.Sprintf("-X 'main.Version=%s'", gitVersion)
+	if err := sh.RunWith(map[string]string{
+		"GOARCH": arch,
+	}, "go", "build", "-ldflags="+ldflags, "-o", "build/coraza-spoa"); err != nil {
 		return err
 	}
 	return nil

main.go

@@ -6,27 +6,35 @@ package main
 import (
 	"context"
 	"flag"
+	"fmt"
 	"net"
 	"net/http"
 	"os"
 	"os/signal"
 	"runtime"
+	"runtime/debug"
 	"runtime/pprof"
 	"syscall"
+	_ "unsafe"
 
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/rs/zerolog"
 
 	"github.com/corazawaf/coraza-spoa/internal"
 )
 
+var (
+	Version = "dev"
+)
+
 var (
 	configPath     string
 	validateConfig bool
 	autoReload     bool
 	cpuProfile     string
 	memProfile     string
 	metricsAddr    string
+	version        bool
 	globalLogger   = zerolog.New(os.Stderr).With().Timestamp().Logger()
 )
 
@@ -37,8 +45,17 @@ func main() {
 	flag.StringVar(&cpuProfile, "cpuprofile", "", "write cpu profile to `file`")
 	flag.StringVar(&memProfile, "memprofile", "", "write memory profile to `file`")
 	flag.StringVar(&metricsAddr, "metrics-addr", "", "ip:port bind for prometheus metrics")
+	flag.BoolVar(&version, "version", false, "show version and exit")
 	flag.Parse()
 
+	if version {
+		fmt.Printf("Coraza SPOA Version: %s\n", Version)
+		if bi, ok := debug.ReadBuildInfo(); ok {
+			fmt.Printf("Build Info: %s", bi.String())
+		}
+		return
+	}
+
 	if configPath == "" {
 		globalLogger.Fatal().Msg("Configuration file is not set")
 	}