first commit

pkg/mysql/mysql.go

@@ -0,0 +1,92 @@
+package mysql
+
+import (
+	"fmt"
+
+	"gorm.io/driver/mysql"
+	"gorm.io/gorm"
+	"gorm.io/gorm/schema"
+	"gorm.io/plugin/dbresolver"
+)
+
+type Config struct {
+	Host     string
+	Port     int
+	User     string
+	Password string
+	Database string
+	Charset  string
+	Prefix   string
+
+	ReadHost     string
+	ReadPort     int
+	ReadUser     string
+	ReadPassword string
+	ReadDatabase string
+}
+
+func New(c Config) (*gorm.DB, error) {
+
+	dsn := buildDSN(c.User, c.Password, c.Host, c.Port, c.Database, c.Charset)
+	db, err := gorm.Open(mysql.New(mysql.Config{
+		DSN:                       dsn,
+		DefaultStringSize:         256,
+		DisableDatetimePrecision:  true,
+		DontSupportRenameIndex:    true,
+		DontSupportRenameColumn:   true,
+		SkipInitializeWithVersion: false,
+	}), &gorm.Config{
+		NamingStrategy: schema.NamingStrategy{
+			TablePrefix: c.Prefix,
+		},
+	})
+	if err != nil {
+		return nil, fmt.Errorf("mysql open: %w", err)
+	}
+
+	readDSN := buildReadDSN(c)
+	if readDSN != "" {
+		if err := db.Use(dbresolver.Register(dbresolver.Config{
+			Sources:  []gorm.Dialector{mysql.Open(dsn)},
+			Replicas: []gorm.Dialector{mysql.Open(readDSN)},
+			Policy:   dbresolver.RandomPolicy{},
+		})); err != nil {
+			return nil, fmt.Errorf("mysql dbresolver: %w", err)
+		}
+	}
+
+	return db, nil
+}
+
+func buildReadDSN(c Config) string {
+	if c.ReadHost == "" {
+		return ""
+	}
+
+	port := c.ReadPort
+	if port == 0 {
+		port = c.Port
+	}
+	user := c.ReadUser
+	if user == "" {
+		user = c.User
+	}
+	password := c.ReadPassword
+	if password == "" {
+		password = c.Password
+	}
+	database := c.ReadDatabase
+	if database == "" {
+		database = c.Database
+	}
+	charset := c.Charset
+	if charset == "" {
+		charset = "utf8mb4"
+	}
+	return buildDSN(user, password, c.ReadHost, port, database, charset)
+}
+
+func buildDSN(user, password, host string, port int, database, charset string) string {
+	return fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=%s&parseTime=True&loc=Local",
+		user, password, host, port, database, charset)
+}