# omhdfs: Hadoop Filesystem Output Module

Module Name: | omhdfs
Author: | Rainer Gerhards <rgerhards@adiscon.com>

## Purpose

This module supports writing message into files on Hadoop’s HDFS file system.

## Configuration Parameters

Note

Parameter names are case-insensitive.

### `obsolete legacy` Directives

`obsolete legacy` directive | type | default | mandatory
--- | --- | --- | ---
`$OMHDFSFileName` | word | none | no

The name of the file to which the output data shall be written.

`obsolete legacy` directive | type | default | mandatory
--- | --- | --- | ---
`$OMHDFSHost` | word | default | no

Name or IP address of the HDFS host to connect to.

`obsolete legacy` directive | type | default | mandatory
--- | --- | --- | ---
`$OMHDFSPort` | integer | 0 | no

Port on which to connect to the HDFS host.

`obsolete legacy` directive | type | default | mandatory
--- | --- | --- | ---
`$OMHDFSDefaultTemplate` | word | RSYSLOG_FileFormat | no

Default template to be used when none is specified. This saves the work of specifying the same template ever and ever again. Of course, the default template can be overwritten via the usual method.

## Caveats/Known Bugs

Building omhdfs is a challenge because we could not yet find out how to integrate Java properly into the autotools build process. The issue is that HDFS is written in Java and libhdfs uses JNI to talk to it. That requires that various system-specific environment options and paths be set correctly. At this point, we leave this to the user. If someone knows how to do it better, please drop us a line!

- In order to build, you need to set these environment variables BEFORE running ./configure:

  - JAVA_INCLUDES - must have all include paths that are needed to build JNI C programs, including the -I options necessary for gcc. An example is # export JAVA_INCLUDES=”-I/usr/lib/jvm/java-1.6.0-openjdk-1.6.0.0.x86_64/include -I/usr/lib/jvm/java-1.6.0-openjdk-1.6.0.0.x86_64/include/linux”

  - JAVA_LIBS - must have all library paths that are needed to build JNI C programs, including the -l/-L options necessary for gcc. An example is # export export JAVA_LIBS=”-L/usr/java/jdk1.6.0_21/jre/lib/amd64 -L/usr/java/jdk1.6.0_21/jre/lib/amd64/server -ljava -ljvm -lverify”

- As of HDFS architecture, you must make sure that all relevant environment variables (the usual Java stuff and HADOOP’s home directory) are properly set.

- As it looks, libhdfs makes Java throw exceptions to stdout. There is no known work-around for this (and it usually should not case any troubles.

## Examples

### Example 1

    $ModLoad omhdfs
    $OMHDFSFileName /var/log/logfile \*.\* :omhdfs:

See also

Help with configuring/using `Rsyslog`:

- Mailing list - best route for general questions

- GitHub: rsyslog source project - detailed questions, reporting issues that are believed to be bugs with `Rsyslog`

- Stack Exchange (View, Ask) - experimental support from rsyslog community

See also

Contributing to `Rsyslog`:

- Source project: rsyslog project README.

- Documentation: rsyslog-doc project README

Copyright 2008-2020 Rainer Gerhards (Großrinderfeld), and Others.