Logstash Filter to run ElasticSearch Queries Dynamically on Events in Scala

The text discusses the development of a Logstash filter in Scala for evaluating events against Elasticsearch-style queries, providing a detailed guide on how to implement such a filter. It distinguishes this filter from the built-in Logstash Elasticsearch filter, emphasizing its purpose to check if an event matches a given query and take action accordingly. The process involves transforming Elasticsearch queries into simplified flat expressions using Scala, which are then utilized to tag events that satisfy the queries. The article outlines the necessary modifications to a Gradle build configuration for compiling Scala code and integrating it with Java, and it details testing the Logstash filter using a sample configuration. The author advocates for using Java or Scala for plugin development due to performance benefits and shares insights into optimizing queries for efficient event tagging.