tHDFSConnection Standard properties

Property type

Either Built-in or Repository

Built-in: No property data stored centrally.

Repository: Select the repository file in which the properties are stored. The fields that follow are completed automatically using the data retrieved.

Distribution

1. Select Import from existing version to import an officially supported distribution as base and then add other required jar files which the base distribution does not provide.

2. Select Import from zip to import the configuration zip for the custom distribution to be used. This zip file should contain the libraries of the different Hadoop elements and the index file of these libraries.

   Note that custom versions are not officially supported by Talend . Talend and its community provide you with the opportunity to connect to custom versions from Talend Studio but cannot guarantee that the configuration of whichever version you choose will be easy, due to the wide range of different Hadoop distributions and versions that are available. As such, you should only attempt to set up such a connection if you have sufficient Hadoop experience to handle any issues on your own.

   Information noteNote:

   In this dialog box, the active check box must be kept selected so as to import the jar files pertinent to the connection to be created between the custom distribution and this component.

   For a step-by-step example about how to connect to a custom distribution and share this connection, see Hortonworks.

Version

Select the version of the Hadoop distribution you are using. The available options vary depending on the component you are using.

• HDFS
• WebHDFS. WebHDFS with SSL is not supported yet.
• ADLS. Only Azure Data Lake Storage Gen1 is supported.

The schemes present on this list vary depending on the distribution you are using and only the scheme that appears on this list with a given distribution is officially supported by Talend.

Once a scheme is selected, the corresponding syntax such as webhdfs://localhost:50070/ for WebHDFS is displayed in the field for the NameNode location of your cluster.

NameNode URI

Type in the URI of the Hadoop NameNode, the master node of a Hadoop system. For example, we assume that you have chosen a machine called masternode as the NameNode, then the location is hdfs://masternode:portnumber. If you are using WebHDFS, the location should be webhdfs://masternode:portnumber; WebHDFS with SSL is not supported yet.

Inspect the classpath for configurations

Select this check box to allow the component to check the configuration files in the directory you have set with the $HADOOP_CONF_DIR variable and directly read parameters from these files in this directory. This feature allows you to easily change the Hadoop configuration for the component to switch between different environments, for example, from a test environment to a production environment.

In this situation, the fields or options used to configure Hadoop connection and/or Kerberos security are hidden.

<!-- Put site-specific property overrides in this file. --> 
<configuration> 
    <property> 
        <name>talend.kerberos.authentication </name> 
        <value>kinit </value>
         <description> Set the Kerberos authentication method to use. Valid values are: kinit or keytab.  </description> 
    </property> 
    <property> 
        <name>talend.kerberos.keytab.principal </name>
        <value>user@BIGDATA.COM </value>
        <description> Set the keytab's principal name.  </description>
    </property> 
    <property>   
        <name>talend.kerberos.keytab.path </name> 
        <value>/kdc/user.keytab </value> 
        <description> Set the keytab's path.  </description> 
    </property> 
    <property> 
        <name>talend.encryption </name> 
        <value>none </value> 
        <description> Set the encryption method to use. Valid values are: none or ssl.  </description> 
    </property> 
    <property> 
        <name>talend.ssl.trustStore.path </name> 
        <value>ssl </value> 
        <description> Set SSL trust store path.  </description> 
    </property> 
    <property> 
        <name>talend.ssl.trustStore.password </name> 
        <value>ssl </value> 
        <description> Set SSL trust store password.  </description> 
    </property> 
</configuration>

The parameters read from these configuration files override the default ones used by Talend Studio. When a parameter does not exist in these configuration files, the default one is used.

Use kerberos authentication

If you are accessing the Hadoop cluster running with Kerberos security, select this check box, then, enter the Kerberos principal name for the NameNode in the field displayed. This enables you to use your username to authenticate against the credentials stored in Kerberos.

This check box is available depending on the Hadoop distribution you are connecting to.

Select the Use a keytab to authenticate check box to log into a Kerberos-enabled system using a given keytab file. A keytab file contains pairs of Kerberos principals and encrypted keys. You need to enter the principal to be used in the Principal field and the access path to the keytab file itself in the Keytab field. This keytab file must be stored in the machine in which your Job actually runs, for example, on a Talend JobServer.

Note that the user that executes a keytab-enabled Job is not necessarily the one a principal designates but must have the right to read the keytab file being used. For example, the username you are using to execute a Job is user1 and the principal to be used is guest; in this situation, ensure that user1 has the right to read the keytab file to be used.

User name

User authentication name of HDFS.

Enter the membership including the authentication user under which the HDFS instances were started. This field is available depending on the distribution you are using.

Hadoop properties

Use datanode hostname

Select the Use datanode hostname check box to allow the Job to access datanodes via their hostnames. This actually sets the dfs.client.use.datanode.hostname property to true.

Setup HDFS encryption configurations

If the HDFS transparent encryption has been enabled in your cluster, select the Setup HDFS encryption configurations check box and in the HDFS encryption key provider field that is displayed, enter the location of the KMS proxy.

For further information about the HDFS transparent encryption and its KMS proxy, see Transparent Encryption in HDFS.

tStatCatcher Statistics

Select this check box to collect log data at the component level.

Global Variables

ERROR_MESSAGE: the error message generated by the component when an error occurs. This is an After variable and it returns a string. This variable functions only if the Die on error check box is cleared, if the component has this check box.

A Flow variable functions during the execution of a component while an After variable functions after the execution of the component.

To fill up a field or expression with a variable, press Ctrl+Space to access the variable list and choose the variable to use from it.

For more information about variables, see Using contexts and variables.

Usage rule

This component is generally used with other Hadoop components.

Prerequisites

The Hadoop distribution must be properly installed, so as to guarantee the interaction with Talend Studio . The following list presents MapR related information for example.

• Ensure that you have installed the MapR client in the machine where Talend Studio is, and added the MapR client library to the PATH variable of that machine. According to MapR's documentation, the library or libraries of a MapR client corresponding to each OS version can be found under MAPR_INSTALL\ hadoop\hadoop-VERSION\lib\native. For example, the library for Windows is \lib\native\MapRClient.dll in the MapR client jar file.

  Without adding the specified library or libraries, you may encounter the following error: no MapRClient in java.library.path.

• Set the -Djava.library.path argument, for example, in the Job Run VM arguments area of the Run/Debug view in the Preferences dialog box in the Window menu. This argument provides to Talend Studio the path to the native library of that MapR client. This allows the subscription-based users to make full use of the Data viewer to view locally in Talend Studio the data stored in MapR.

For further information about how to install a Hadoop distribution, see the manuals corresponding to the Hadoop distribution you are using.

Limitations

JRE 1.6+ is required.