LXD host update scripts

Description

Maintenance scripts to routinely update all containers on a LXD host
Composed of an application script and a cron script, to run all commands in a screen session and be able to monitor progress if needed
Mitigate silent fails with Healthchecks.io

Variants:

• Ubuntu
• Alpine

Setup

1. Host scripts go into /usr/local/bin
   Edit HEALTHCHECK variable
   Make sure ( $6 == "ubuntu" ) matches with the corresponding fields for that OS under lxc list -cn,image.os
   Or see further below
2. Containers' local scripts go into /usr/local/bin/ as well
   Typically: /usr/local/bin/localupdate.sh
3. Copy the cron file into /etc/cron.weekly
   Edit the variable SCRIPT_NAME
4. Make sure all scripts and cron are executable

Assumptions

LXD path

We assume LXD is installed with snap.
If LXD is installed from source or binaries, the path might need to be edited in the scrips.

Check LXC path:

> $ which lxc                                                                                                                                                                              
/snap/bin/lxc

Then edit:

...
LXC="/snap/bin/lxc"
...

image.os field

Update scripts rely on it filter containers based on the image.os field available in LXD, to avoid running unnecessarily on all containers and snapshoting containers multiple times.

Run: lxc list -cn,image.os
For any empty field, run: lxc exec $container -- cat /etc/os-release | grep PRETTY_NAME | cut -d '"' -f2
And declare the OS in the containers config: lxc config set $container image.os $ImageOS

For instance with container1, before:

> $ lxc list -cn,image.os
+---------------------+-------------+
|        NAME         |  IMAGE OS   |
+---------------------+-------------+
| container1          |             |
+---------------------+-------------+

And after:

> $ lxc config set container1 image.os ubuntu
> $ lxc list -cn,image.os                                                                  
+---------------------+-------------+
|        NAME         |  IMAGE OS   |
+---------------------+-------------+
| container1          | ubuntu      |
+---------------------+-------------+

Containers local updates

We also execute any localupdate.sh script that would be on the container's /usr/local/bin directory.
This is primarily used to update non-repoed softwares - docker containers, pihole, etc. - together with the rest of the system.