title: Sqoop list-databases requires --connection-manager
body: <p>I'm using Hortonworks Sandbox HDP 2.4 and I can't use the <code>list-databases</code> tool, although <code>import</code> is working.</p>
  
  <pre><code>sqoop list-databases --connect jdbc:mysql://&lt;ip&gt;:&lt;port&gt;/  --driver com.mysql.jdbc.Driver --username=myusername -P
  </code></pre>
  
  <p>This the result that I get</p>
  
  <pre><code>16/08/11 07:44:47 WARN sqoop.ConnFactory: Parameter --driver is set to an explicit driver however appropriate connection manager is not being set (via --connection-manager). Sqoop is going to fall back to org.apache.sqoop.manager.GenericJdbcManager. Please specify explicitly which connection manager should be used next time.
  16/08/11 07:44:47 INFO manager.SqlManager: Using default fetchSize of 1000
  16/08/11 07:44:47 ERROR manager.SqlManager: Generic SqlManager.listDatabases() not implemented.
  Could not retrieve database list from server
  16/08/11 07:44:47 ERROR tool.ListDatabasesTool: manager.listDatabases() returned null
  </code></pre>
  
  <p>The response says that I need to set the <code>--connection-manager</code> parameter, which I do not know.</p>
  
  <p>If I will take out the --driver argument, I get exception:</p>
  
  <pre><code>16/08/11 07:48:12 ERROR manager.CatalogQueryManager: Failed to list databases
  com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
  
  The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
          at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
          at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
          at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
          at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
          at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
          at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116)
          at com.mysql.jdbc.MysqlIO.&lt;init&gt;(MysqlIO.java:344)
          at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2336)
          at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2370)
          at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2154)
          at com.mysql.jdbc.ConnectionImpl.&lt;init&gt;(ConnectionImpl.java:792)
          at com.mysql.jdbc.JDBC4Connection.&lt;init&gt;(JDBC4Connection.java:49)
          at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
          at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
          at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
          at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
          at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
          at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:381)
          at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
          at java.sql.DriverManager.getConnection(DriverManager.java:571)
          at java.sql.DriverManager.getConnection(DriverManager.java:215)
          at org.apache.sqoop.manager.SqlManager.makeConnection(SqlManager.java:885)
          at org.apache.sqoop.manager.GenericJdbcManager.getConnection(GenericJdbcManager.java:52)
          at org.apache.sqoop.manager.CatalogQueryManager.listDatabases(CatalogQueryManager.java:57)
          at org.apache.sqoop.tool.ListDatabasesTool.run(ListDatabasesTool.java:49)
          at org.apache.sqoop.Sqoop.run(Sqoop.java:148)
          at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:76)
          at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:184)
          at org.apache.sqoop.Sqoop.runTool(Sqoop.java:226)
          at org.apache.sqoop.Sqoop.runTool(Sqoop.java:235)
          at org.apache.sqoop.Sqoop.main(Sqoop.java:244)
  Caused by: java.net.ConnectException: Connection refused
          at java.net.PlainSocketImpl.socketConnect(Native Method)
          at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
          at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
          at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
          at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
          at java.net.Socket.connect(Socket.java:579)
          at java.net.Socket.connect(Socket.java:528)
          at java.net.Socket.&lt;init&gt;(Socket.java:425)
          at java.net.Socket.&lt;init&gt;(Socket.java:241)
          at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:258)
          at com.mysql.jdbc.MysqlIO.&lt;init&gt;(MysqlIO.java:295)
          ... 24 more
  16/08/11 07:48:12 ERROR sqoop.Sqoop: Got exception running Sqoop: java.lang.RuntimeException: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
  
  The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
  java.lang.RuntimeException: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
  
  The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
          at org.apache.sqoop.manager.CatalogQueryManager.listDatabases(CatalogQueryManager.java:73)
          at org.apache.sqoop.tool.ListDatabasesTool.run(ListDatabasesTool.java:49)
          at org.apache.sqoop.Sqoop.run(Sqoop.java:148)
          at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:76)
          at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:184)
          at org.apache.sqoop.Sqoop.runTool(Sqoop.java:226)
          at org.apache.sqoop.Sqoop.runTool(Sqoop.java:235)
          at org.apache.sqoop.Sqoop.main(Sqoop.java:244)
  Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
  
  The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
          at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
          at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
          at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
          at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
          at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
          at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116)
          at com.mysql.jdbc.MysqlIO.&lt;init&gt;(MysqlIO.java:344)
          at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2336)
          at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2370)
          at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2154)
          at com.mysql.jdbc.ConnectionImpl.&lt;init&gt;(ConnectionImpl.java:792)
          at com.mysql.jdbc.JDBC4Connection.&lt;init&gt;(JDBC4Connection.java:49)
          at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
          at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
          at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
          at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
          at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
          at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:381)
          at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
          at java.sql.DriverManager.getConnection(DriverManager.java:571)
          at java.sql.DriverManager.getConnection(DriverManager.java:215)
          at org.apache.sqoop.manager.SqlManager.makeConnection(SqlManager.java:885)
          at org.apache.sqoop.manager.GenericJdbcManager.getConnection(GenericJdbcManager.java:52)
          at org.apache.sqoop.manager.CatalogQueryManager.listDatabases(CatalogQueryManager.java:57)
          ... 7 more
  Caused by: java.net.ConnectException: Connection refused
          at java.net.PlainSocketImpl.socketConnect(Native Method)
          at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:339)
          at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:200)
          at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:182)
          at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
          at java.net.Socket.connect(Socket.java:579)
          at java.net.Socket.connect(Socket.java:528)
          at java.net.Socket.&lt;init&gt;(Socket.java:425)
          at java.net.Socket.&lt;init&gt;(Socket.java:241)
          at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:258)
          at com.mysql.jdbc.MysqlIO.&lt;init&gt;(MysqlIO.java:295)
          ... 24 more
  </code></pre>
  
  <p>What's the value for <code>--connection-manager</code>?</p>