feat: MySQL/PG 实时指标采集 + 版本检测修复 + 密码加密存储

- 新增 getMySQLMetrics(): SHOW GLOBAL STATUS 采集连接数/QPS/延迟/运行时间
- 新增 getPostgresMetrics(): pg_stat_activity 采集活跃连接+运行时间
- 修复 extractVersion(): 支持 Redis 'version: 7.4.9, mode: standalone' 格式(逗号截断)
- CreateInstance/UpdateInstance: 创建/更新时自动加密密码(enc: 前缀)
- InstanceMetrics handler: MySQL/PG 分别调用专属 metrics 函数

backend/internal/handler/connection_tester.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"database/sql"
 	"fmt"
+	"strconv"
 	"strings"
 	"time"
 
@@ -83,8 +84,12 @@ func extractVersion(msg, prefix string) string {
 		return ""
 	}
 	ver := msg[idx+len(prefix):]
-	if end := strings.Index(ver, ")"); end > 0 {
-		ver = ver[:end]
+	// Cut at first comma, closing paren, or space (whichever comes first)
+	for _, sep := range []string{")", ",", " "} {
+		if end := strings.Index(ver, sep); end > 0 {
+			ver = ver[:end]
+			break
+		}
 	}
 	return strings.TrimSpace(ver)
 }
@@ -280,7 +285,164 @@ func getRedisMetrics(instance *model.Instance) map[string]interface{} {
 	return metrics
 }
 
-// getDB opens a real database connection and returns *sql.DB
+// getMySQLMetrics fetches live MySQL metrics (connections, QPS, latency, uptime, version)
+func getMySQLMetrics(instance *model.Instance) map[string]interface{} {
+	password := instance.Password
+	if strings.HasPrefix(password, "enc:") {
+		decrypted, err := decryptPassword(strings.TrimPrefix(password, "enc:"))
+		if err == nil {
+			password = decrypted
+		}
+	}
+
+	metrics := map[string]interface{}{
+		"status":      "offline",
+		"connections": 0,
+		"qps":         0,
+		"latency":     0,
+		"uptime":      "-",
+		"version":     "",
+	}
+	if instance.Version != nil {
+		metrics["version"] = *instance.Version
+	}
+
+	dsn := fmt.Sprintf("%s:%s@tcp(%s:%d)/?timeout=5s&parseTime=true",
+		instance.Username, password, instance.Host, instance.Port)
+	db, err := sql.Open("mysql", dsn)
+	if err != nil {
+		return metrics
+	}
+	defer db.Close()
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	// Latency from simple query
+	start := time.Now()
+	if err := db.PingContext(ctx); err != nil {
+		return metrics
+	}
+	metrics["latency"] = time.Since(start).Milliseconds()
+	metrics["status"] = "online"
+
+	// Fetch STATUS variables
+	statusVars := map[string]string{}
+	rows, err := db.QueryContext(ctx, "SHOW GLOBAL STATUS WHERE Variable_name IN "+
+		"('Threads_connected','Queries','Uptime','Connections','Slow_queries')")
+	if err == nil {
+		defer rows.Close()
+		for rows.Next() {
+			var name, value string
+			rows.Scan(&name, &value)
+			statusVars[name] = value
+		}
+	}
+
+	if v, ok := statusVars["Threads_connected"]; ok {
+		n, _ := strconv.Atoi(v)
+		metrics["connections"] = n
+	}
+	if v, ok := statusVars["Uptime"]; ok {
+		secs, _ := strconv.Atoi(v)
+		if secs > 86400 {
+			metrics["uptime"] = fmt.Sprintf("%d 天", secs/86400)
+		} else if secs > 3600 {
+			metrics["uptime"] = fmt.Sprintf("%d 小时", secs/3600)
+		} else {
+			metrics["uptime"] = fmt.Sprintf("%d 分钟", secs/60)
+		}
+	}
+	// QPS = Queries / Uptime
+	if q, ok := statusVars["Queries"]; ok {
+		if u, ok2 := statusVars["Uptime"]; ok2 {
+			qi, _ := strconv.ParseFloat(q, 64)
+			ui, _ := strconv.ParseFloat(u, 64)
+			if ui > 0 {
+				metrics["qps"] = int(qi / ui)
+			}
+		}
+	}
+
+	// Version from DB if not already set
+	if instance.Version == nil || *instance.Version == "" {
+		var ver string
+		if err := db.QueryRowContext(ctx, "SELECT VERSION()").Scan(&ver); err == nil {
+			metrics["version"] = ver
+		}
+	}
+
+	return metrics
+}
+
+// getPostgresMetrics fetches live PostgreSQL metrics
+func getPostgresMetrics(instance *model.Instance) map[string]interface{} {
+	password := instance.Password
+	if strings.HasPrefix(password, "enc:") {
+		decrypted, err := decryptPassword(strings.TrimPrefix(password, "enc:"))
+		if err == nil {
+			password = decrypted
+		}
+	}
+
+	metrics := map[string]interface{}{
+		"status":      "offline",
+		"connections": 0,
+		"qps":         0,
+		"latency":     0,
+		"uptime":      "-",
+		"version":     "",
+	}
+	if instance.Version != nil {
+		metrics["version"] = *instance.Version
+	}
+
+	dsn := fmt.Sprintf("postgres://%s:%s@%s:%d/postgres?sslmode=disable&connect_timeout=5",
+		instance.Username, password, instance.Host, instance.Port)
+	db, err := sql.Open("pgx", dsn)
+	if err != nil {
+		return metrics
+	}
+	defer db.Close()
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	start := time.Now()
+	if err := db.PingContext(ctx); err != nil {
+		return metrics
+	}
+	metrics["latency"] = time.Since(start).Milliseconds()
+	metrics["status"] = "online"
+
+	// Fetch pg_stat_activity counts
+	var activeConns int
+	db.QueryRowContext(ctx, "SELECT count(*) FROM pg_stat_activity WHERE state = 'active'").Scan(&activeConns)
+	metrics["connections"] = activeConns
+
+	// Uptime
+	var uptimeSecs int
+	if err := db.QueryRowContext(ctx, "SELECT extract(epoch from now() - pg_postmaster_start_time())::int").Scan(&uptimeSecs); err == nil {
+		if uptimeSecs > 86400 {
+			metrics["uptime"] = fmt.Sprintf("%d 天", uptimeSecs/86400)
+		} else if uptimeSecs > 3600 {
+			metrics["uptime"] = fmt.Sprintf("%d 小时", uptimeSecs/3600)
+		} else {
+			metrics["uptime"] = fmt.Sprintf("%d 分钟", uptimeSecs/60)
+		}
+	}
+
+	// Version
+	if instance.Version == nil || *instance.Version == "" {
+		var ver string
+		if err := db.QueryRowContext(ctx, "SELECT version()").Scan(&ver); err == nil {
+			metrics["version"] = ver
+		}
+	}
+
+	return metrics
+}
+
 func getDBConnection(instance *model.Instance, dbName string) (*sql.DB, error) {
 	password, err := decryptPassword(instance.Password)
 	if err != nil {