Add rotating log info by @minrk to docs

docs/source/troubleshooting.md

@@ -18,6 +18,7 @@ problem and how to resolve it.
 - How do I increase the number of pySpark executors on YARN?
 - How do I use JupyterLab's prerelease version with JupyterHub?
 - How do I set up JupyterHub for a workshop (when users are not known ahead of time)?
+- How do I set up rotating daily logs?
 
 [*Troubleshooting commands*](#troubleshooting-commands)
 
@@ -226,6 +227,31 @@ notebook servers to default to JupyterLab:
 
 Users will need a GitHub account to login and be authenticated by the Hub.
 
+### How do I set up rotating daily logs?
+
+You can do this with [logrotate](http://www.linuxcommand.org/man_pages/logrotate8.html),
+or pipe to `logger` to use syslog instead of directly to a file.
+
+For example, with this logrotate config file:
+
+```
+/var/log/jupyterhub.log {
+  copytruncate
+  daily
+}
+```
+
+and run this daily by putting a script in `/etc/cron.daily/`:
+
+```bash
+logrotate /path/to/above-config
+```
+
+Or use syslog:
+
+    jupyterhub | logger -t jupyterhub
+
+
 ## Troubleshooting commands
 
 The following commands provide additional detail about installed packages,
@@ -252,7 +278,7 @@ jupyterhub --debug
 
 ## Toree integration with HDFS rack awareness script
 
-The Apache Toree kernel will an issue, when running with JupyterHub, if the standard HDFS 
+The Apache Toree kernel will an issue, when running with JupyterHub, if the standard HDFS
 rack awareness script is used. This will materialize in the logs as a repeated WARN:
 
 ```bash
@@ -267,8 +293,7 @@ SyntaxError: Missing parentheses in call to 'print'
 
 In order to resolve this issue, there are two potential options.
 
-1. Update HDFS core-site.xml, so the parameter "net.topology.script.file.name" points to a custom 
+1. Update HDFS core-site.xml, so the parameter "net.topology.script.file.name" points to a custom
 script (e.g. /etc/hadoop/conf/custom_topology_script.py). Copy the original script and change the first line point
 to a python two installation (e.g. /usr/bin/python).
 2. In spark-env.sh add a Python 2 installation to your path (e.g. export PATH=/opt/anaconda2/bin:$PATH).
-