How can I stop unattended-upgrades from rebooting the machine?

I just had a look at my Amazon EC2 instance and noticed I had 20 minutes exactly of downtime. I didn't know what caused it so I logged in to SSH and tried upgrading my packages, and saw that the unattended-upgrades package needed upgrading. I went ahead and did this.

After searching it seems like this package can automatically reboot your machine. Not sure why I didn't get to configure this as it came with the OS, but oh well.

Does anyone know how to prevent the package from automatically rebooting? Or how to stop it updating packages altogether? I can do that myself.

Verify that in the configuration file: /etc/apt/apt.conf.d/50unattended-upgrades you have set:

Unattended-Upgrade::Automatic-Reboot "false";

This will prevent the software to issue reboot also if needed by the upgrades.

Documentation

To disable automatic upgrades altogether, just remove the package. Try:

sudo apt-get remove unattended-upgrades

See Ubuntu docs for more info. However, if you want to keep the package and configure its behaviour, see this question's solution How do I enable automatic updates?