These instructions are for the JAVA build NOT Ruby Gem build and publish.
This is a Logstash plugin with a large amount of Java code.
The Java source is dependent on the logstash-core jar and the logstash-core-event jar.
These jars can be found in the gems that are resolved via the s.add_runtime_dependency "logstash-core-plugin-api", "~> 2.0" line in the gemspec.
So different versions of these gems can be installed as time goes by. The gradle build dependencies cannot refer to a static location and version.
These Rake tasks allow for Gradle to be dependent on Rubygems.
rake vendor- this task calls "./gradlew vendor" but only after have done the "bundle_install" rake taskrake bundle_install- this task callsbundle installthen puts the output ofbundle show logstash-coreandbundle show logstash-core-eventinto the "gradle.properties" file.
Each time a new gem version of logstash-core-plugin-api is released we need to run rake vendor to verify that any changes to the Java in logstash-core and logstash-core-event are still compatible with their usage in this plugin.
Run rake vendor
Travis is set to use rake write_gradle_properties before its build task
See the Gradle "vendor" task to understand how the the jar is generated.