In order to troubleshoot a vyOS issue which we’ve been experiencing lately I attempted to upgrade to the latest vyOS release on a .OVA deployed appliance that was running the older 1.2.1 release.
The vyOS upgrade documentation shows the command required to install a new version is simply:
add system image https://downloads.vyos.io/rolling/current/amd64/vyos-1.2.0-rolling%2B201810030440-amd64.iso
However later on in the same article the command response shows the error:
We do not have enough disk space to install this image!
We need 344880 KB, but we only have 17480 KB.
So what is using the space on the appliance and how can we resolve this issue?
Basically, using ‘sudo du -hs /var’ shows us that 968MB of data is consumed within the /var folder and most of this relates to the wtmp and wtmp.1 files. What are those files? They are simply large binary rolling log files which are written to in order to record any login attempts, with wtmp.1 being the rolled up previous versions which are being retained.
We don’t need anything close to that level of logging in our lab environments, so the following commands modify the retention period and log interval to 1 hour maximum.
sudo nano /etc/logrotate.conf
Edit the lines to change from ‘weekly’ and ‘4’ represent a month’s worth of logs to:
#rotate log files weekly hourly #keep 4 weeks worth of backlogs rotate 1
Which should retain a rolling log of any login attempts during the last hour. Once this is done you can delete the previous wtmp.1 rollup, apply the vyOS update and then reboot (once only) in order to apply the latest code version now that you have sufficient space:
sudo rm /var/log/wtmp.1 add system image http://172.20.12.142:8080/vyos-1.2-rolling-201911110217-amd64.iso sudo reboot
NB – in my example I’m hosting the .ISO file which I downloaded on a simple HTTP web server on the internal network
After you’ve finished the upgrade you could always revert the logging configuration back to the defaults, but the main sticking point here is the limited available space once a rollup of logs has become quite large and I didn’t want to have to fix this again in the future.