problem posts page 8

PHP-FPM / Apache caching symlinks

At Cogneato, we use symlinks to point the web server to different versions of our software for websites. Sometimes, especially on our Ubuntu server, which uses PHP-FPM to serve PHP files through Apache, I was noticing problems caused by scripts being loaded from the previous symlink destination when I changed to the new one. There seems to be some sort of caching going on. The solution was to restart PHP-FPM and Apache after switching the symlinks. On Ubuntu, this looks like:

ln -s /path/to/new-version /path/to/software-link \
&& sudo service php7.2-fpm restart \
&& sudo service apache2 graceful

where the 7.2 is the version of PHP being used. Haven’t noticed the problem since.


Custom logic for unattended upgrades reboot

The Ubuntu / Debian unattended-upgrades package has an option to automatically reboot as needed when it upgrades packages. It will do this without user input, at a chosen time. However, it doesn’t allow for any conditions beyond need and time. I found a need for more nuance recently, so I had to disable the built-in functionality and set up my own script on a cron job.

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Automatically deal with conf changes using unattended-upgrades

For Ubuntu servers, I use the unattended-upgrades package to automate keeping the system and packages up to date. I recently noticed some of Cogneato’s servers showing packages needing to be updated for multiple days. When I looked in unattended-upgrades.log (in folder /var/log/unattended-upgrades/), I found the message “WARNING Package something has conffile prompt and needs to be upgraded manually”. Basically, there was a change to a configuration file and it didn’t know how to handle it.

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