Why does the Linux monitoring agent restart during automatic OS updates?

Why does the Linux monitoring agent restart during automatic OS updates?

A brief service restart that can trigger agent down or agent restarted alerts and spikes in event noise.

Why this happens

Automatic updates run on a timer (e.g., apt-daily-upgrade.timer).
If the systemd package (or other core libraries) is updated, the update process requests a systemd daemon re-exec to load the new version.
As a result, many services, including the Site24x7 full-stack agent service, are briefly stopped and started. This is normal and intended to keep the system manager secure and up to date. This activity is not triggered by or exclusive to Site24x7 services.

How to confirm

Check when automatic upgrades ran:
  1. systemctl list-timers 'apt*'
  2. journalctl -u apt-daily-upgrade.service --since "YYYY-MM-DD 00:00" --until "YYYY-MM-DD 23:59"
Replace the placeholders with the time period under scrutiny.
Alternate method:
  1. grep -i "apt-daily" /var/log/syslog*
Notes
This command works in most OSs and distros. Use commands appropriate for your OS.

How to exclude expected alerts during updates

Create a recurring maintenance window in your monitoring tool that aligns with your automatic update schedule.

FAQ

  1. Did the agent crash?
    No. The restart was triggered by the system manager.
  2. Will this happen again?
    Yes, it will occur whenever when the systemd service manager executes due to any operations. Scheduling maintenance windows can prevent noisy alerts.