eksa-admin node should include unattended-upgrades

[displague]

The EKS-A Admin node is running Ubuntu 20.04. We should ensure the latest updates are installed and continue to be installed through use of the unattended-upgrades package.

[cprivitere]

Adding the following to the cloud-init should do it.

in packages:

• unattended-upgrades
  packages_update: true
  packages_upgrade: true
  package_reboot_if_required: true

in runcmd:

- sed 's,//      "${distro_id}:${distro_codename}-updates";,        "${distro_id}:${distro_codename}-updates";,' /etc/apt/apt.conf.d/50unattended-upgrades
- sed 's,//Unattended-Upgrade::Automatic-Reboot "false";,Unattended-Upgrade::Automatic-Reboot "true";,' /etc/apt/apt.conf.d/50unattended-upgrades

[displague]

We'll also want to ensure (somehow) that the node isn't rebooted while the cluster is coming up for the first time.
Maybe we can disable it at install and at schedule the enablement for a few hours later.

[cprivitere]

Options:

• disable autoreboot
• Set reboot time to 2AM
• Do your at scheme.
• Calculate the autoreboot time to be 2 hours (or some other offset) from current time.

[cprivitere]

Looks like the upfront upgrade (package_upgrade: true) may be a bad idea. Just had it hang and never complete.