Using MySQL / MariaDB via SSH in Golang

In this post I will show how easy it is to connect to MySQL/MariaDB on a server via SSH using the local SSH-AGENT or password

package main

import (
    "database/sql"
    "fmt"
    "net"
    "os"

    "github.com/go-sql-driver/mysql"
    "golang.org/x/crypto/ssh"
    "golang.org/x/crypto/ssh/agent"
)

type ViaSSHDialer struct {
    client *ssh.Client
}

func (self *ViaSSHDialer) Dial(addr string) (net.Conn, error) {
    return self.client.Dial("tcp", addr)
}

func main() {

    sshHost := "example.com"   // SSH Server Hostname/IP
    sshPort := 22              // SSH Port
    sshUser := "ssh-user"      // SSH Username
    sshPass := "ssh-pass"      // Empty string for no password
    dbUser := "dbuser"         // DB username
    dbPass := "dbpass"         // DB Password
    dbHost := "localhost:3306" // DB Hostname/IP
    dbName := "database"       // Database name

    var agentClient agent.Agent
    // Establish a connection to the local ssh-agent
    if conn, err := net.Dial("unix", os.Getenv("SSH_AUTH_SOCK")); err == nil {
        defer conn.Close()

        // Create a new instance of the ssh agent
        agentClient = agent.NewClient(conn)
    }

    // The client configuration with configuration option to use the ssh-agent
    sshConfig := &ssh.ClientConfig{
        User: sshUser,
        Auth: []ssh.AuthMethod{},
    }

    // When the agentClient connection succeeded, add them as AuthMethod
    if agentClient != nil {
        sshConfig.Auth = append(sshConfig.Auth, ssh.PublicKeysCallback(agentClient.Signers))
    }
    // When there's a non empty password add the password AuthMethod
    if sshPass != "" {
        sshConfig.Auth = append(sshConfig.Auth, ssh.PasswordCallback(func() (string, error) {
            return sshPass, nil
        }))
    }

    // Connect to the SSH Server
    if sshcon, err := ssh.Dial("tcp", fmt.Sprintf("%s:%d", sshHost, sshPort), sshConfig); err == nil {
        defer sshcon.Close()

        // Now we register the ViaSSHDialer with the ssh connection as a parameter
        mysql.RegisterDial("mysql+tcp", (&ViaSSHDialer{sshcon}).Dial)

        // And now we can use our new driver with the regular mysql connection string tunneled through the SSH connection
        if db, err := sql.Open("mysql", fmt.Sprintf("%s:%s@mysql+tcp(%s)/%s", dbUser, dbPass, dbHost, dbName)); err == nil {

            fmt.Printf("Successfully connected to the db\n")

            if rows, err := db.Query("SELECT id, name FROM table ORDER BY id"); err == nil {
                for rows.Next() {
                    var id int64
                    var name string
                    rows.Scan(&id, &name)
                    fmt.Printf("ID: %d  Name: %s\n", id, name)
                }
                rows.Close()
            } else {
                fmt.Printf("Failure: %s", err.Error())
            }

            db.Close()

        } else {

            fmt.Printf("Failed to connect to the db: %s\n", err.Error())
        }

    }
}

Link to gist:
https://gist.github.com/vinzenz/d8e6834d9e25bbd422c14326f357cce0