#How To Access MySQL-MGR Instances

There are multiple ways to connect to a MySQL-MGR instance when accessing it from a business application. This section describes how to choose a connection address to access the MySQL-MGR instance and provides examples for demonstration.

#Applicable scenarios

#Common client programs

The example demonstrates programs using JDBC and GORM clients. Please refer to the corresponding framework documentation for other clients.

When using the code, please modify the relevant variables to your actual values. The variable descriptions are as follows:

#JDBC

1. Cluster Internal Access

   import java.sql.*;
   public class Main {
       static final String DB_URL = "jdbc:mysql://mgr-0:3306,mgr-1:3306,mgr-2:3306/mysql";
       static final String USER = "root";
       static final String PASS = "123456";
       public static void main(String[] args) {
           try {
               Connection conn = DriverManager.getConnection(DB_URL,USER,PASS);
               Statement statement = conn.createStatement();
           }catch(SQLException se){
               se.printStackTrace();
           }
       }
   }

2. External Access to the Cluster - via NodePort

   import java.sql.*;
   public class Main {
       static final String DB_URL = "jdbc:mysql://192.168.1.100:32630,192.168.1.101:32630,192.168.1.102:32630/mysql";
       static final String USER = "root";
       static final String PASS = "123456";
       public static void main(String[] args) {
           try {
               Connection conn = DriverManager.getConnection(DB_URL,USER,PASS);
               Statement statement = conn.createStatement();
           }catch(SQLException e){
               e.printStackTrace();
           }
       }
   }

#GORM

1. Cluster Internal Access

   import (
       "gorm.io/driver/mysql"
       "gorm.io/gorm"
       "gorm.io/plugin/dbresolver"
   )
   
   func main() {
       writeDSN:="root:123456@tcp(mgr-read-write:32631)/mysql"
       readDSN := "root:123456@tcp(mgr-read-only:32630)/mysql"
       db, err := gorm.Open(mysql.Open(writeDSN), &gorm.Config{})
       if err != nil {
           panic(err)
       }
       err = db.Use(dbresolver.Register(dbresolver.Config{
           Replicas:          []gorm.Dialector{mysql.Open(readDSN)},
           Policy:            dbresolver.RandomPolicy{},
           TraceResolverMode: true,
       }))
       if err != nil {
           panic(err)
       }
   }

2. External Access to the Cluster - via NodePort

   package main
   
   import (
       "gorm.io/driver/mysql"
       "gorm.io/gorm"
       "gorm.io/plugin/dbresolver"
   )
   
   func main() {
       writeDSNs := []string{
           "root:123456@tcp(192.168.18.130:32631)/mysql",
           "root:123456@tcp(192.168.18.131:32631)/mysql",
           "root:123456@tcp(192.168.18.132:32631)/mysql",
       }
       readDSNs := []string{
           "root:123456@tcp(192.168.18.131:32630)/mysql",
           "root:123456@tcp(192.168.18.132:32630)/mysql",
           "root:123456@tcp(192.168.18.133:32630)/mysql",
       }
       db, err := gorm.Open(mysql.Open(writeDSNs[0]), &gorm.Config{})
       if err != nil {
           panic(err)
       }
       sources := make([]gorm.Dialector, 0)
       replicas := make([]gorm.Dialector, 0)
       for _, dsn := range writeDSNs {
           sources = append(sources, mysql.Open(dsn))
       }
       for _, dsn := range readDSNs {
           replicas = append(replicas, mysql.Open(dsn))
       }
       err = db.Use(dbresolver.Register(dbresolver.Config{
           Sources:           sources,
           Replicas:          replicas,
           Policy:            dbresolver.RandomPolicy{},
           TraceResolverMode: true,
       }))
       if err != nil {
           panic(err)
       }
   }