Pour que nos serveurs puissent appliquer automatiquement les dernieres mises a jour, y compris celle necessitant un redemarrage, nous avons configurer un redemarrage automatique en modifiant /etc/apt/apt.conf.d/20auto-upgrades de la maniere suivante :

 // Do automatic removal of new unused dependencies after the upgrade
 // (equivalent to apt-get autoremove)
+Unattended-Upgrade::Remove-Unused-Dependencies "true";
-//Unattended-Upgrade::Remove-Unused-Dependencies "false";

 // Automatically reboot *WITHOUT CONFIRMATION* if
 //  the file /var/run/reboot-required is found after the upgrade 
+Unattended-Upgrade::Automatic-Reboot "true";
-//Unattended-Upgrade::Automatic-Reboot "false";

 // Automatically reboot even if there are users currently logged in.
 //Unattended-Upgrade::Automatic-Reboot-WithUsers "true";
@@ -89,7 +89,7 @@ Unattended-Upgrade::Automatic-Reboot "true";
 // If automatic reboot is enabled and needed, reboot at the specific
 // time instead of immediately
 //  Default: "now"
+Unattended-Upgrade::Automatic-Reboot-Time "02:00";
-//Unattended-Upgrade::Automatic-Reboot-Time "02:00";

Pour eviter que les serveurs procedent tous au reboot en meme temps, l'heure peut etre modifiee.