Flexible run-time logging configuration in Apache Solr 4.10.x

In a multi-shard setup it is useful to be able to change log level in runtime without going to each and every shard's admin page.

For example, we can set the logging to WARN level during massive posting sessions and back to INFO, when serving the user queries.

In solr 4.10.2 these one-liners do the trick:

# set logging level to WARN,

# saves disk space and speeds up massive posting 

curl -s http://localhost:8983/solr/admin/info/logging \

                       --data-binary "set=root:WARN&wt=json" 

# set logging level to INFO,

# suitable for serving the user queries 

curl -s http://localhost:8983/solr/admin/info/logging \

                       --data-binary "set=root:INFO&wt=json"

Back from Solr you get a JSON with the current status of each configured logger.