Changes for new minimum Solr Versions

This is a list of improvements that can be made to the Solr Operator when it is guaranteed that all Solrs will be at least a certain version.

So when upgrading the minimum supported Solr Version for the operator, we can then go ahead and make all improvements that align with versions <= the new minimum supported version.

8.x

8.11

• SOLR-7642: Solr will create a chroot if necessary using the ZK_CREATE_CHROOT envVar

9.x

9.0

• SOLR-14957: Prometheus exporter bin is now in the PATH for the Solr docker image
• SOLR-14957: The default Prometheus exporter config is now on the classpath, and it does not need to be provided on startup.
• SOLR-15914: Solr Modules can be included via an Environment variable, no need to use sharedLib
• SOLR-9575: No need to pre-fill the solr.xml in SOLR_HOME (combined with SOLR-14999)

Future Wishlist

• Have a bin/solr command to healthcheck the Solr Node (possibly split between live and ready). This command would need to support ZKACLs as well as SSL and basicAuth/jwt. (related to SOLR-15199)