Initial commit: OpenVPN Manager v1.0

OpenVPN Web management console with multi-instance support, client cert
issuance, traffic/connection auditing, certificate expiry reminders,
auto backup/restore.

Stack:
- Backend: Go 1.21+ (Gin + JWT)
- Frontend: Vue 3 + Element Plus + ECharts + Vite
- Storage: JSON file (db.json) + filesystem (pki/, instances/, clients/, backups/)

Features:
- Multi-instance OpenVPN management (independent port/proto/subnet/PKI)
- One-click client certificate issuance with .ovpn (embedded certs)
- Certificate expiry reminders (30-day threshold)
- Connection log parsing (status-version 3)
- Auto backup/restore (tar.gz)
- Audit log for all write operations
- JWT auth (12h TTL)
- One-line install.sh for Ubuntu/Debian/RHEL/Fedora

backend/cmd/server/main.go

@@ -0,0 +1,88 @@
+package main
+
+import (
+	"flag"
+	"log"
+	"os"
+	"path/filepath"
+
+	"openvpn-manager/internal/api"
+	"openvpn-manager/internal/config"
+	"openvpn-manager/internal/service"
+	"openvpn-manager/internal/store"
+	"openvpn-manager/pkg/openvpn"
+)
+
+func main() {
+	dataDir := flag.String("data", "", "data directory (default $OVPNMGR_DATA or ./data)")
+	distDir := flag.String("dist", "", "frontend dist directory (default $OVPNMGR_DIST or ./dist)")
+	flag.Parse()
+
+	if *dataDir == "" {
+		*dataDir = os.Getenv("OVPNMGR_DATA")
+	}
+	if *dataDir == "" {
+		*dataDir = "./data"
+	}
+	if *distDir == "" {
+		*distDir = os.Getenv("OVPNMGR_DIST")
+	}
+	if *distDir == "" {
+		*distDir = "./dist"
+	}
+	abs, _ := filepath.Abs(*dataDir)
+	cfg := config.Load(abs)
+
+	if err := os.MkdirAll(cfg.PKIDir(), 0o700); err != nil {
+		log.Fatalf("mkdir pki: %v", err)
+	}
+	if err := os.MkdirAll(cfg.InstancesDir(), 0o755); err != nil {
+		log.Fatalf("mkdir instances: %v", err)
+	}
+	if err := os.MkdirAll(cfg.ClientsDir(), 0o755); err != nil {
+		log.Fatalf("mkdir clients: %v", err)
+	}
+	if err := os.MkdirAll(cfg.BackupsDir(), 0o755); err != nil {
+		log.Fatalf("mkdir backups: %v", err)
+	}
+
+	st, err := store.Open(cfg.DBFile())
+	if err != nil {
+		log.Fatalf("open store: %v", err)
+	}
+	ovm := openvpn.NewManager(cfg.OpenVPNBin, cfg.DataDir)
+	if err := ovm.EnsureCA(); err != nil {
+		log.Printf("warn: ensure CA: %v", err)
+	}
+	svc := service.New(cfg, st, ovm)
+
+	addr := cfg.Host + ":" + itoa(cfg.Port)
+	log.Printf("openvpn-manager listening on %s, data=%s, dist=%s", addr, cfg.DataDir, *distDir)
+	srv := api.NewServer(cfg, svc)
+	if err := srv.Router(*distDir).Run(addr); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func itoa(n int) string {
+	if n == 0 {
+		return "0"
+	}
+	neg := false
+	if n < 0 {
+		neg = true
+		n = -n
+	}
+	var buf [20]byte
+	i := len(buf)
+	for n > 0 {
+		i--
+		buf[i] = byte('0' + n%10)
+		n /= 10
+	}
+	if neg {
+		i--
+		buf[i] = '-'
+	}
+	return string(buf[i:])
+}