Example Spring Boot web application running embedded Apache Felix OSGI Container

The idea is to be able to:

• load basic Spring Boot App running an embedded Felix Framework.
• Add functionality using plain jars using standard annotations like Spring Web controllers and ServletFilter etc
• Auto detect and serve embedded static resources

Spring boot

• Create App Entrypoint as @SpringBootApplication
• Customise Spring Boot start Banner
• Configure Spring default logging to use log4j2.xml in resources
• Add a way for Felix framework to use Spring boot properties in internal environment

Felix

• Create FelixService as Spring Service Component and ApplicationReadyEvent Event Listener to initialise it
• Configure Felix to load some predefined framework bundles

Gradle

• Generate custom start.sh, start.bat script in output distribution
• Create Task to copy configurable OSGI Framework bundles into framework_bundles folder in distribution
• Generate an empty plugins folder in the distribution
• Generate zip and tar.gz distributions which include the ./framework_bundles and ./plugins folder plus start scripts.

Additional Custom Bundles for initial framework load

• PluginServices

  • Services for turning plain JAR into OSGI bundle using BND tools
  • OSGI bundle activation processing pipeline with hooks for custom processing e.g.
    • Detecting and wiring Servlets, Filters via annotations
    • Detecting and wiring Spring MVC Controllers, RestControllers etc
    • Detecting and wiring custom @AuthRequired annotations etc
    • Detecting static resources

• PluginFileWatcherService - watch a dir for new jars then use PluginServices to process it.