Tags: nix, server

This post will show one way to backup Home Assistant automatically. I’ll use Nix to set things up but I will also show the resulting configuration files so you can follow along even if you do not use Nix.

The idea is to have home assistant itself create a backup using an automation that is scheduled to run on a regular basis. Then, you can use whatever method to store that backup in a secure location.

Backup Automation

Create the following shell command (excerpt from configuration.nix):

shell_command:
  delete_backups: find /var/lib/hass/backups -type f -delete

And create the following automation:

alias: Create Backup on Schedule
mode: single
trigger:
- minutes: '5'
  platform: time_pattern
action:
- data: {}
  service: shell_command.delete_backups
- data: {}
  service: backup.create

This script will run on the 5th minute of every hour to 1/ delete old backups 2/ create a new backup. The backup will live inside the Home Assistant’s backup/ folder.

In Nix, you would do:

services.home-assistant = {
  config = {
    "automation manual" = [
      {
        alias = "Create Backup on Schedule";
        trigger = [
          {
            platform = "time_pattern";
            minutes = "5";
          }
        ];
        action = [
          {
            service = "shell_command.delete_backups";
            data = {};
          }
          {
            service = "backup.create";
            data = {};
          }
        ];
        mode = "single";
      }
    ];

    shell_command = {
      delete_backups = "find ${config.services.home-assistant.configDir}/backups -type f -delete";
    };
  };
};

Note that I combine declarative and UI defined automations.

Allow backup user to access Home Assistant backup folder

Create a backup user and make it member of the Home Assistant group:

useradd backup --system --groups hass

In nix:

users.groups.hass = {
  members = [ "backup" ];
};

Now, we need to ensure the backup user has access to the Home Assistant folder by enabling the “read” and “execute” group bits. First, by editing the Home Assistant service config and updating the UMask settings:

systemctl edit home-assistant.service

Then enter:

UMask=0027

Finally, restart the service.

In nix:

users.users.hass.homeMode = "0750";

systemd.services.home-assistant.serviceConfig = {
  UMask = lib.mkForce "0027";
};

Second, you need to update the files already created by Home Assistant:

sudo find /var/lib/hass -type d -exec chmod -r g+rx '{}' ';'
sudo find /var/lib/hass -type f -exec chmod -r g+r '{}' ';'

Backup Home-Assistant with and without Nix

Backup Automation

Allow backup user to access Home Assistant backup folder