NEXUS-10014 has a good summary of the options for clearing bundle cache on startup.
The resolution of NEXUS-10014 meant:
- the UI installer touches a clean_cache file inside the chosen data directory so that the bundle cache is cleared on startup
- the archive installers include a clean_cache file inside their default ( but not optimal ) data subdirectory
According to some recent analysis we still have significant user base using the archives (zip/tgz) to install Nexus. In the use case of upgrade using the archive bundle, a user needs to edit bin/nexus.vmoptions and change the karaf.data property value to reference their existing, to be upgraded data directory. They then also need to manually create a clean_cache file there so that on startup the cache is cleared.
This issue is about eliminating the step of creating the clean_cache file and instead, configuring Nexus to always reload the bundle cache on startup. Other than some so far reportedly insignificant startup processing of bundle caching, I haven't heard of a good reason not to do this. Implementing this aims to make the upgrade process simpler.