GUACAMOLE-852: Support either MySQL or MariaDB JDBC drivers.

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/src/main/java/org/apache/guacamole/auth/mysql/MySQLAuthenticationProviderModule.java

@@ -41,6 +41,12 @@ public class MySQLAuthenticationProviderModule implements Module {
      */
     private final Properties driverProperties = new Properties();
     
+    /**
+     * The MySQL-compatible driver that should be used to talk to the database
+     * server.
+     */
+    private MySQLDriver mysqlDriver;
+    
     /**
      * Creates a new MySQL authentication provider module that configures
      * driver and MyBatis properties using the given environment.
@@ -73,13 +79,32 @@ public class MySQLAuthenticationProviderModule implements Module {
         // Allow use of multiple statements within a single query
         driverProperties.setProperty("allowMultiQueries", "true");
         
+        // Get the MySQL-compatible driver to use.
+        mysqlDriver = environment.getMySQLDriver();
+
     }
 
     @Override
     public void configure(Binder binder) {
 
-        // Bind MySQL-specific properties
+        // Check which MySQL-compatible driver is in use
-        JdbcHelper.MySQL.configure(binder);
+        switch(mysqlDriver) {
+            
+            // Bind MySQL-specific properties
+            case MYSQL:
+                JdbcHelper.MySQL.configure(binder);
+                break;
+                
+            // Bind MariaDB-specific properties
+            case MARIADB:
+                JdbcHelper.MariaDB.configure(binder);
+                break;
+                
+            default:
+                throw new UnsupportedOperationException(
+                    "A driver has been specified that is not supported by this module."
+                );
+        }
 
         // Bind MyBatis properties
         Names.bindProperties(binder, myBatisProperties);

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/src/main/java/org/apache/guacamole/auth/mysql/MySQLDriver.java

@@ -0,0 +1,37 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.guacamole.auth.mysql;
+
+/**
+ * The possible JDBC drivers to use when talking to a MySQL-compatible database
+ * server.
+ */
+public enum MySQLDriver {
+
+    /**
+     * MySQL driver.
+     */
+    MYSQL,
+
+    /**
+     * MariaDB driver.
+     */
+    MARIADB;
+}

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/src/main/java/org/apache/guacamole/auth/mysql/MySQLDriverProperty.java

@@ -0,0 +1,52 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.guacamole.auth.mysql;
+
+import org.apache.guacamole.GuacamoleException;
+import org.apache.guacamole.GuacamoleServerException;
+import org.apache.guacamole.properties.GuacamoleProperty;
+
+/**
+ * A property whose value is a MySQL-compatible JDBC driver.  The string values
+ * of either "mysql" or "mariadb" are parsed into the corresponding MySQLDriver
+ * enum value. Any values that are not valid result in a parse error.
+ */
+public abstract class MySQLDriverProperty implements GuacamoleProperty<MySQLDriver> {
+
+    @Override
+    public MySQLDriver parseValue(String value) throws GuacamoleException {
+
+        // If no value provided, return null.
+        if (value == null)
+            return null;
+
+        // MySQL Driver
+        if (value.equals("mysql"))
+            return MySQLDriver.MYSQL;
+
+        // MariaDB Driver
+        if (value.equals("mariadb"))
+            return MySQLDriver.MARIADB;
+
+        throw new GuacamoleServerException("MySQL driver must be one of \"mysql\" or \"mariadb\".");
+
+    }
+
+}

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/src/main/java/org/apache/guacamole/auth/mysql/MySQLEnvironment.java

@@ -51,6 +51,11 @@ public class MySQLEnvironment extends JDBCEnvironment {
      */
     private static final MySQLVersion MYSQL_SUPPORTS_CTE = new MySQLVersion(8, 0, 1, false);
 
+    /**
+     * The default MySQL-compatible driver to use, if not specified.
+     */
+    private static final MySQLDriver DEFAULT_DRIVER = MySQLDriver.MYSQL;
+    
     /**
      * The default host to connect to, if MYSQL_HOSTNAME is not specified.
      */
@@ -164,6 +169,25 @@ public class MySQLEnvironment extends JDBCEnvironment {
         return new MySQLPasswordPolicy(this);
     }
 
+    /**
+     * Returns the MySQL driver that will be used to talk to the MySQL-compatible
+     * database server hosting the Guacamole Client database.  If unspecified
+     * a default value of MySQL will be used.
+     * 
+     * @return
+     *     The MySQL driver that will be used to communicate with the MySQL-
+     *     compatible server.
+     * 
+     * @throws GuacamoleException 
+     *     If guacamole.properties cannot be parsed.
+     */
+    public MySQLDriver getMySQLDriver() throws GuacamoleException {
+        return getProperty(
+            MySQLGuacamoleProperties.MYSQL_DRIVER,
+            DEFAULT_DRIVER
+        );
+    }
+    
     /**
      * Returns the hostname of the MySQL server hosting the Guacamole
      * authentication tables. If unspecified, this will be "localhost".

extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-mysql/src/main/java/org/apache/guacamole/auth/mysql/MySQLGuacamoleProperties.java

@@ -33,6 +33,17 @@ public class MySQLGuacamoleProperties {
      */
     private MySQLGuacamoleProperties() {}
     
+    /**
+     * The JDBC driver that should be used to talk to MySQL-compatible servers.
+     */
+    public static final MySQLDriverProperty MYSQL_DRIVER =
+            new MySQLDriverProperty() {
+
+        @Override
+        public String getName() { return "mysql-driver"; }
+
+    };
+
     /**
      * The hostname of the MySQL server hosting the Guacamole authentication 
      * tables.