Logstash-forwarder-java is a log shipper program written in java. This is in fact a java version of logstash-forwarder by jordansissel. Here are a few features of this program :

compatible with Java 5 runtime
lightweight : package size is ~2MB
configuration compatible with logstash-forwarder
lumberjack output (including zlib compression)

Why ?

Logstash-forwarder is written in go. This programming language is not available on all platforms (for example AIX), that's why a java version is more portable.

Logstash runs on java and provides a lumberjack output, but the file input doesn't run on all plaforms (for example AIX) and logstash requires a recent JVM. Moreover Logstash is heavier : big package and more system resources.

So logstash-forwarder-java is a solution for those who want a portable, lightweight log shipper for their ELK stack.

How to install it ?

Download one of the following archives :

Or download the maven project and run maven package. Then you can install one of the archives located in the target directory.

How to run it ?

Just run this command :

java -jar logstash-forwarder-java-X.Y.Z.jar -config /path/to/config/file.json

Differences with logstash-forwarder

Configuration

The configuration file is the same (json format), but there are a few differences :

the ssl ca parameter points to a java keystore containing the root certificate of the server, not a PEM file
comments are C-style comments
the stdin input is not yet implemented

Command-line options

Some options are the same :

config (but only for a file, not a directory)
quiet
idle-timeout (renamed idletimeout)
spool-size (renamed spoolsize)
help

There are a few more options :

debug : turn on debug logging level
trace : turn on trace logging level