Selfhosted

That’ll be my impetus to learn how to write a script.

This part caught my eye. You were able to do all that other stuff without ever attempting to write a script? That's surprising and awesome. Assuming you are running everything on a linux server, I feel like a bash script that is run via a cronjob would be your best bet, no need to ssh into the server, just let it do it on it's own. I haven't tested any of this but I do have scripts I wrote that do automatic ZFS backups and scrubs; the order should go something like:

open the terminal on the server and type

mkdir scripts

cd scripts

nano docker-updates.sh

type something along the lines of this (I'm still learning docker so adjust the commands to your needs)

#!/bin/bash

cd /path/to/scripts/docker-compose.yml
docker compose pull && docker compose up -d
docker image prune -f

save the file and then type sudo chmod +x ./docker-updates.sh to make it executable

and finally set up a cronjob to run the script at specific intervals. type

crontab -e

or

sudo crontab -e (this is if you want to run the script as root but ideally, you just add your user to the docker group so this shouldn't be needed)

and at the bottom of the file type this and save, that's it:

# runs script at 1am on the first of every month
0 1 1 * * /path/to/scripts/docker-updates.sh

this website will help you choose a different interval

For OS updates you basically do the same thing except the script would look something like: (I forget if you need to type "sudo" or not; it's running as root so I don't think you need it but maybe try it with sudo in front of both "apt"s if it's not working. Also use whatever package manager you have if you aren't using apt)

while in the scripts folder you created earlier

nano os-updates.sh

#!/bin/bash

apt update -y && apt upgrade -y
reboot now

save and don't forget to make it exectuable

then use

sudo crontab -e (because you'll need root privileges to update. this will run the script as root without requiring you to input your password)

# runs script at 12am on the first of every month
0 0 1 * * /path/to/scripts/os-updates.sh