By default, Solr logs to STD ERROR. You likely want to add a log configuration file to have the most control over how Solr logs – see http://wiki.apache.org/solr/LoggingInDefaultJettySetup. To be lazy though (and perhaps safe), let’s make sure STD OUT and STD ERR are nicely logged for us by runit.
This method just logs STD OUT, so lets first edit our Solr run script to redirect STD ERR to STD OUT
Now create a new directory called log in the /etc/sv/solr service directory. Inside this, create another script called run. This script will start the log service, run it under the user mark, and put the log files in the log directory we just made (we use . for the current working directory).
You can find the full tutorial on Lucid Imagination's blog. Just click through the References box link.