Server configuration

Lens server provides you with various configuration options. Administrator can configure the offered services from server, available drivers for query execution, query output options, enabling metrics from server and etc. The configuration parameters and their detailed description and default values are available here. The overridden configuration can be part of lens-site.xml.

Driver configuration

The supported drivers are configured through type and classname in this release. The property lens.server.drivers in server configuration specifies the driver types supported by the system and their corresponding driver implementation.

System can have multiple drivers of same type, for example MySQL and Postgres can be two drivers of type JDBC. The configuration for each driver is specified in its site.xml file which should be present under the folder Server_Conf_location/drivers/driver-type/driver-name. For example, Hive driver's configuration should be specified in LensServer_Install_Location/conf/drivers/hive/hive1/hivedriver-site.xml where hive1 is the driver name. A driver is identified by its fully qualified name which includes the driver type and driver name. For the example discussed above the fully qualified name would be "hive/hive1"

The organization of drivers in the system is illustrated below

  ├── conf
      └── drivers
          ├── hive
          │   ├── hive1
          │   │   └── hivedriver-site.xml
          │   └── hive2
          │       └── hivedriver-site.xml
          └── jdbc
              ├── jdbc1
              │   └── jdbcdriver-site.xml
              └── jdbc2
                  └── jdbcdriver-site.xml

Supported drivers in this version are org.apache.lens.driver.hive.HiveDriver, org.apache.lens.driver.jdbc.JDBCDriver and org.apache.lens.driver.es.ESDriver. The configuration parameters and their description are explained in their respective docs listed below HiveDriver - here JDBCDriver - here ESDriver - here. For overridding configurations, use the appropriate site.xml as listed below hive - hivedriver-site.xml jdbc - jdbc-driver-site.xml es - esdriver-site.xml

Session configuration

The configuration that user can override for each session is documented here. These configuration mostly include query parameters, which can be overriden by query as well. Server should be configured with appropriate values for them in the site file. The overridden configuration can be part of lens-site.xml.