You are in the right place if:
Rolling back puts your server into the state it was in at an earlier date, the one you choose.
Calaos OS automatically records the state of the system: before every software installation or update, and regularly over time. These recordings are called restore points, and they are dated.
You can ask the computer to restart on one of them. It then finds the system exactly as it was on that day.
Rolling back also restores your Calaos configuration.
Your inputs/outputs, rules and scenarios go back to the chosen date as well. Everything you created since will be lost, including the configuration history recorded by the server.
An example: you update on Monday, you create rules on Tuesday, you roll back on Wednesday to Monday — Tuesday’s work disappears.
So retrieve your configuration before confirming. Step 3 below gives you all the time you need.
Restart the computer. Just after power-on, a menu is displayed for five seconds.
Use the arrow keys to enter the submenu listing the restore points, then choose the date you want — usually the most recent one before the problem. Confirm with Enter.
If the menu disappears too quickly, restart and press the up arrow several times as soon as the machine powers on: this stops the countdown and gives you all the time you need to choose.
The system then boots on the chosen restore point.
At this stage the system runs in trial mode: it shows you what your server would look like if you went back to that date, but nothing has been written yet.
If you change your mind, simply restart the computer. It will boot the current system again, as if nothing had happened.
This is the moment to check that this restore point is the right one: does your home automation respond correctly? Has the problem gone? If not, restart and choose an earlier date.
Since rolling back will also restore your Calaos configuration, set it aside now.
The simplest way is to bring it back to your computer with Calaos Installer: menu Calaos Server, option Load project from Calaos Server, then save the project locally. The details are described in Backing up your configuration.
When you have booted on a restore point, the Calaos Home interface automatically displays a window explaining the situation and offering a button to confirm the rollback. You have nothing to look for: click that button.
The window above only appears if a touchscreen is connected. Otherwise, connect to the server over SSH — this works normally, even when booted on a restore point:
ssh root@YOUR_SERVER_ADDRESS
then run:
calaos_rollback
If the command answers Not booted from a readonly btrfs snapshot, the computer did not boot on a restore point but on the usual system. Start again from step 1.
Restart one last time:
reboot
Your server boots into the restored state. You are done.
The system logs are kept. They are not part of the restore points, so you can still look afterwards at what happened at the time of the incident. See Logs.
If no restore point gives you a working server back, a full reinstall remains: make a new USB stick, reinstall Calaos OS following Installation, then send your configuration back from Calaos Installer.
Restore points rely on Btrfs snapshots, managed by snapper. To list them from a terminal:
snapper list
The details of the mechanism, of the automatic retention and of what is covered or not are described in Under the hood.