Renaming munin nodes and preserving history

Once you have changed your server naming convention or just decided to rename on (or all) of your servers you will also need to update server in name in your monitoring tools. If you are using munin - here is step-by-step solution for you.

We assume you are using example.com as your domain and want to rename oldhost.example.com to newhost.example.com.

1. Backup existing data and configs

cd /backup/
tar cvpzf munin_lib.tar.gz.$(date +%Y%m%d) /var/lib/munin
tar cvpzf munin_html.tar.gz.$(date +%Y%m%d) /www/munin
cp /etc/munin/munin.conf munin.conf.$(date +%Y%m%d)

2. Remove unneeded and legacy stuff (if any)

cd /var/lib/munin/example.com
rm old* test* temp*
cd /var/vhosts/monitor/munin/clickmein.com
rm -R old* test* temp* 

3. Disable munin cronjobs

mv /etc/cron.d/munin /etc/cron.d/munin.disabled

4. Rename actual rrd files

for file in /var/lib/munin/example.com/*.rrd; do mv $file `echo $file|sed 's/oldhost\.example\.com/newhost\.example\.com/'`; done

5. Edit munin config 
I do strongly recommend you prepare all the changes before disabling cronjobs to minimize munin downtime! Just prepare all the changes and save once you have done Step 4.

vi /etc/munin/munin.conf

And then type the following command sequence to replace all occurances in config file in vi editor.

:%s/oldhost\.example\.com/newhost\.example\.com/g

6. Enable cronjob

 mv /etc/cron.d/munin.disabled /etc/cron.d/munin

That's all! Now just wait 5 minutes (default cronjob interval) to see updates on the munin web-interface.

References:
http://aaltonen.co/2010/12/30/change-munin-node-hostname/
http://beeznest.wordpress.com/2011/06/13/howto-rename-munin-node-without-loosing-history/