tHDFSConnection Standard properties - 7.0

HDFS

author
Talend Documentation Team
EnrichVersion
7.0
EnrichProdName
Talend Big Data
Talend Big Data Platform
Talend Data Fabric
Talend Open Studio for Big Data
Talend Real-Time Big Data Platform
task
Data Governance > Third-party systems > File components (Integration) > HDFS components
Data Quality and Preparation > Third-party systems > File components (Integration) > HDFS components
Design and Development > Third-party systems > File components (Integration) > HDFS components
EnrichPlatform
Talend Studio

These properties are used to configure tHDFSConnection running in the Standard Job framework.

The Standard tHDFSConnection component belongs to the Big Data and the File families.

The component in this framework is available in all Talend products with Big Data and in Talend Data Fabric.

Basic settings

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

Select the cluster you are using from the drop-down list. The options in the list vary depending on the component you are using. Among these options, the following ones requires specific configuration:
  • If available in this Distribution drop-down list, the Microsoft HD Insight option allows you to use a Microsoft HD Insight cluster. For this purpose, you need to configure the connections to the HD Insightcluster and the Windows Azure Storage service of that cluster in the areas that are displayed.For detailed explanation about these parameters, see Configuring the connection manually.

  • If you select Amazon EMR, see the following article about how to configure the connection: Amazon EMR - Getting Started .

  • The Custom option allows you to connect to a cluster different from any of the distributions given in this list, that is to say, to connect to a cluster not officially supported by Talend .

  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.

    In Talend Exchange, members of Talend community have shared some ready-for-use configuration zip files which you can download from this Hadoop configuration list and directly use them in your connection accordingly. However, because of the ongoing evolution of the different Hadoop-related projects, you might not be able to find the configuration zip corresponding to your distribution from this list; then it is recommended to use the Import from existing version option to take an existing distribution as base to add the jars required by your distribution.

    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 the 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.

    Note:

    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 Connecting to a custom Hadoop distribution.

Hadoop version

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

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.

If you want to use certain parameters such as the Kerberos parameters but these parameters are not included in these Hadoop configuration files, you need to create a file called talend-site.xml and put this file into the same directory defined with $HADOOP_CONF_DIR. This talend-site.xml file should read as follows:
<!-- 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 the 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 user name to authenticate against the credentials stored in Kerberos.
  • If this cluster is a MapR cluster of the version 5.0.0 or later, you can set the MapR ticket authentication configuration in addition or as an alternative by following the explanation in Connecting to a security-enabled MapR.

    Keep in mind that this configuration generates a new MapR security ticket for the username defined in the Job in each execution. If you need to reuse an existing ticket issued for the same username, leave both the Force MapR ticket authentication check box and the Use Kerberos authentication check box clear, and then MapR should be able to automatically find that ticket on the fly.

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

Use a keytab to authenticate

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 user name 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.

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; if this WebHDFS is secured with SSL, the scheme should be swebhdfs and you need to use a tLibraryLoad in the Job to load the library required by the secured WebHDFS.

User name

User authentication name of HDFS.

Group

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

Talend Studio uses a default configuration for its engine to perform operations in a Hadoop distribution. If you need to use a custom configuration in a specific situation, complete this table with the property or properties to be customized. Then at runtime, the customized property or properties will override those default ones.
  • Note that if you are using the centrally stored metadata from the Repository, this table automatically inherits the properties defined in that metadata and becomes uneditable unless you change the Property type from Repository to Built-in.

For further information about the properties required by Hadoop and its related systems such as HDFS and Hive, see the documentation of the Hadoop distribution you are using or see Apache's Hadoop documentation on http://hadoop.apache.org/docs and then select the version of the documentation you want. For demonstration purposes, the links to some properties are listed below:

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.

Advanced settings

tStatCatcher Statistics

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

Global Variables

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 further information about variables, see Talend Studio User Guide.

Usage

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 the 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. For further information, see the following link from MapR: http://www.mapr.com/blog/basic-notes-on-configuring-eclipse-as-a-hadoop-development-environment-for-mapr.

    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 the 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 the 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.