KairosDB create it’s log files in /opt/kairosdb/log/. It works in a daily basis, so every day a new log is created and named as kairosdb.log; when the next day comes kairosdb.log is compressed and renamed to kairosdb.<YYYY-MM-DD>.log, where <YYYY-MM-DD> is the date when this specific log file was created.
Starting from KairosDB 1.1.2, a more robust logging system will be used. From this version, KairosDB will compress logs everyday in order to minimize the space used for log files. Also, every time a log file reaches 100mb, it will be compressed and a new one will be generated for the same day (until the end of the day, when a new log file will be generated too).
Note: KairosDB uses the well-know Logback framework to manage it’s log files. If you have questions about Logback, please refer to their forums.
If you want to change these logging settings, please take a look at /opt/kairosdb/conf/logging/logback.xml and at Logback documentation.