Logstash HDFS plugin
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README.md

Logstash HDFS plugin

An HDFS plugin for Logstash. This plugin is provided as an external plugin (see Usage below) and is not part of the Logstash project.

Usage

Logstash 1.4.x

Run logstash with the --pluginpath (-p) command line argument to let logstash know where the plugin is. Also, you need to let Java know where your Hadoop JARs are, so set the CLASSPATH variable correctly. On Logstash 1.4.x use the following command (ajusting paths as neccessary of course):

LD_LIBRARY_PATH="/usr/lib/hadoop/lib/native" GEM_HOME=./logstash-1.4.2/vendor/bundle/jruby/1.9 CLASSPATH=$(find ./logstash-1.4.2/vendor/jar -type f -name '*.jar'|tr '\n' ':'):$(find /usr/lib/hadoop-hdfs -type f -name '*.jar' | tr '\n' ':'):$(find /usr/lib/hadoop -type f -name '*.jar' | tr '\n' ':'):/etc/hadoop/conf java org.jruby.Main -I./logstash-1.4.2/lib ./logstash-1.4.2/lib/logstash/runner.rb agent -f logstash.conf -p ./logstash-hdfs/lib

Note that logstash is not executed with java -jar because executable jars ignore external classpath. Instead we put the logstash jar on the class path and call the runner class. Important: the Hadoop configuration dir containing hdfs-site.xml must be on the classpath.

Logstash 1.5.x

Logstash 1.5.x supports distribution of plugins as rubygems which makes life a lot easier. To install the plugin from the version on rubygems:

$LOGSTASH_DIR/bin/plugin install logstash-output-hdfs

Or from source (after checking out the source, run in checkout directory):

$LOGSTASH_DIR/bin/plugin build logstash-output-hdfs.gemspec

Then run logstash with the following command (change jar versions and locations as per your hadoop installation):

LD_LIBRARY_PATH="$HADOOP_DIR/lib/native" CLASSPATH=$HADOOP_DIR/share/hadoop/common/lib/htrace-core-3.0.4.jar:$HADOOP_DIR/share/hadoop/common/lib/protobuf-java-2.5.0.jar:$HADOOP_DIR/share/hadoop/common/lib/commons-cli-1.2.jar:$HADOOP_DIR/share/hadoop/common/lib/slf4j-api-1.7.5.jar:$HADOOP_DIR/share/hadoop/common/lib/hadoop-auth-2.6.0.jar:$HADOOP_DIR/share/hadoop/common/lib/commons-lang-2.6.jar:$HADOOP_DIR/share/hadoop/common/lib/commons-configuration-1.6.jar:$HADOOP_DIR/share/hadoop/common/lib/commons-collections-3.2.1.jar:$HADOOP_DIR/share/hadoop/common/lib/guava-11.0.2.jar:$HADOOP_DIR/share/hadoop/common/lib/commons-logging-1.1.3.jar:$HADOOP_DIR/share/hadoop/hdfs/hadoop-hdfs-2.6.0.jar:$HADOOP_DIR/share/hadoop/common/hadoop-common-2.6.0.jar:$HADOOP_DIR/conf $LOGSTASH_DIR/bin/logstash agent -f logstash.conf

Hadoop paths may need adjustments depending on the distribution and version you are using. The important thing is to have hadoop-hdfs, hadoop-common and the dependencies from common/lib on the classpath.

The following command line will work on most distributions (but will take a little longer to load since it loads many unnecessary jars) - note there may be conflicts with other plugins (e.g. elasticsearch) if you load all the jars:

LD_LIBRARY_PATH="/usr/lib/hadoop/lib/native" CLASSPATH=$(hadoop classpath) $LOGSTASH_DIR/bin/logstash agent -f logstash.conf

HDFS Configuration

By default, the plugin will load Hadoop's configuration from the classpath. However, a logstash configuration option named 'hadoop_config_resources' has been added that will allow the user to pass in multiple configuration locations to override this default configuration.

output {
        hdfs {
            path => "/path/to/output_file.log"
            hadoop_config_resources => ['path/to/configuration/on/classpath/hdfs-site.xml', 'path/to/configuration/on/classpath/core-site.xml']
        }
    }

HDFS Append and rewriting files

Please note, HDFS versions prior to 2.x do not properly support append. See HADOOP-8230 for reference. To enable append on HDFS, set dfs.support.append in hdfs-site.conf (2.x) or dfs.support.broken.append on 1.x, and use the enable_append config option:

output {
    hdfs {
        path => "/path/to/output_file.log"
        enable_append => true
    }
}

If append is not supported and the file already exists, the plugin will cowardly refuse to reopen the file for writing unless enable_reopen is set to true. This is probably a very bad idea, you have been warned!

HFDS Flush

Flush and sync don't actually work as promised on HDFS (see HDFS-536). In Hadoop 2.x, hflush provides flush-like functionality and the plugin will use hflush if it is available. Nevertheless, flushing code has been left in the plugin in case flush and sync will work on some HDFS implementation.

License

The plugin is released under the Apache V2 license.