WALG-1665. User proper DSNs in MySQL documentation & validate DSN for…

…mat it earlier (#1692)

docs/MySQL.md

@@ -9,7 +9,7 @@ Configuration
 
 * `WALG_MYSQL_DATASOURCE_NAME`
 
-To configure the connection string for MySQL. Required. Format ```user:password@host/dbname```
+To configure the connection string for MySQL. Required. [DSN format](https://github.com/go-sql-driver/mysql#dsn-data-source-name) ```user:password@tcp(host)/dbname```
 
 * `WALG_MYSQL_SSL_CA`
 
@@ -63,7 +63,7 @@ To configure the server id of the binlog server. Should be unique for each repli
 
 * `WALG_MYSQL_BINLOG_SERVER_REPLICA_SOURCE`
 
-To configure the connection string that will be used by `binlog-server` to connect to your MySQL. [DSN format](https://github.com/go-sql-driver/mysql#dsn-data-source-name): ```user:password@host/dbname```
+To configure the connection string that will be used by `binlog-server` to connect to your MySQL. [DSN format](https://github.com/go-sql-driver/mysql#dsn-data-source-name): ```user:password@tcp(host)/dbname```
 
 > **Operations with binlogs**: If you'd like to do binlog operations with wal-g don't forget to [activate the binary log](https://mariadb.com/kb/en/activating-the-binary-log/) by starting mysql/mariadb with [--log-bin](https://mariadb.com/kb/en/replication-and-binary-log-server-system-variables/#log_bin) and [--log-basename](https://mariadb.com/kb/en/mysqld-options/#-log-basename)=\[name\].
 
@@ -256,7 +256,7 @@ In that case MySQL backup is a plain SQL script.
 Here's typical wal-g configuration for that case:
 
 ```bash
- WALG_MYSQL_DATASOURCE_NAME=user:pass@localhost/mysql                                                                                                               
+ WALG_MYSQL_DATASOURCE_NAME=user:pass@tcp(localhost)/mysql                                                                                                               
  WALG_STREAM_CREATE_COMMAND="mysqldump --all-databases --single-transaction --set-gtid-purged=ON"                                                                                                                               
  WALG_STREAM_RESTORE_COMMAND="mysql"
  WALG_MYSQL_BINLOG_REPLAY_COMMAND='mysqlbinlog --stop-datetime="$WALG_MYSQL_BINLOG_END_TS" "$WALG_MYSQL_CURRENT_BINLOG" | mysql'
@@ -277,7 +277,7 @@ wal-g can work as replication source to do fast PiTR. In this case it will serve
  WALG_MYSQL_BINLOG_SERVER_PASSWORD="walgpwd"
  WALG_MYSQL_BINLOG_SERVER_ID=99
 
- WALG_MYSQL_BINLOG_SERVER_REPLICA_SOURCE="user:password@127.0.0.1:3306/db"
+ WALG_MYSQL_BINLOG_SERVER_REPLICA_SOURCE="user:password@tcp(127.0.0.1:3306)/db"
 ```
 
 Restore procedure is straightforward:

internal/databases/mysql/binlog_server_handler.go

@@ -15,8 +15,10 @@ import (
 	"github.com/go-mysql-org/go-mysql/mysql"
 	"github.com/go-mysql-org/go-mysql/replication"
 	"github.com/go-mysql-org/go-mysql/server"
+	mysqldriver "github.com/go-sql-driver/mysql"
 	"github.com/google/uuid"
 	"github.com/wal-g/tracelog"
+
 	"github.com/wal-g/wal-g/internal"
 	conf "github.com/wal-g/wal-g/internal/config"
 	"github.com/wal-g/wal-g/pkg/storages/storage"
@@ -264,6 +266,12 @@ func HandleBinlogServer(since string, until string) {
 	startTS, untilTS, _, err = getTimestamps(st.RootFolder(), since, until, "")
 	tracelog.ErrorLogger.FatalOnError(err)
 
+	// validate WALG_MYSQL_BINLOG_SERVER_REPLICA_SOURCE
+	replicaSource, err := conf.GetRequiredSetting(conf.MysqlBinlogServerReplicaSource)
+	tracelog.ErrorLogger.FatalOnError(err)
+	_, err = mysqldriver.ParseDSN(replicaSource)
+	tracelog.ErrorLogger.FatalOnError(err)
+
 	tracelog.InfoLogger.Printf("Starting binlog server")
 
 	serverAddress, err := conf.GetRequiredSetting(conf.MysqlBinlogServerHost)

internal/databases/mysql/mysql.go

@@ -15,8 +15,9 @@ import (
 	"github.com/wal-g/wal-g/internal/compression"
 
 	gomysql "github.com/go-mysql-org/go-mysql/mysql"
-	"github.com/go-sql-driver/mysql"
+	mysqldriver "github.com/go-sql-driver/mysql"
 	"github.com/wal-g/tracelog"
+
 	"github.com/wal-g/wal-g/internal"
 	conf "github.com/wal-g/wal-g/internal/config"
 	"github.com/wal-g/wal-g/pkg/storages/storage"
@@ -172,7 +173,7 @@ func getMySQLConnectionFromDatasource(datasourceName string) (*sql.DB, error) {
 		if ok := rootCertPool.AppendCertsFromPEM(pem); !ok {
 			return nil, fmt.Errorf("failed to load certificate from %s", caFile)
 		}
-		err = mysql.RegisterTLSConfig("custom", &tls.Config{
+		err = mysqldriver.RegisterTLSConfig("custom", &tls.Config{
 			RootCAs: rootCertPool,
 		})
 		if err != nil {
@@ -189,6 +190,10 @@ func getMySQLConnectionFromDatasource(datasourceName string) (*sql.DB, error) {
 			datasourceName += "?tls=custom"
 		}
 	}
+	_, err := mysqldriver.ParseDSN(datasourceName)
+	if err != nil {
+		return nil, err
+	}
 	db, err := sql.Open("mysql", datasourceName)
 	return db, err
 }