Logstash, an open-source data processing pipeline, can be optimized for maintainability and reusability by using modular components stored in separate files, which are combined to create pipelines. This approach addresses the complexities and code duplication issues that arise when processing events from multiple input sources. By utilizing the glob expression to specify which files to include, Logstash can maintain an alphabetical order of execution, ensuring that shared logic across pipelines is effectively managed. The blog illustrates the setup of unique pipelines using components stored in specifically named configuration files for inputs, filters, and outputs, demonstrating how this modular technique simplifies pipeline management and enhances code clarity. Furthermore, this method allows for the reuse of common logic across different pipelines, with the potential addition of pipeline-to-pipeline communication to further enhance modularity.