How to set up a backup server for snapshots¶

How to configure a backup service that will backup snapshots of the production sites of your customers.

Each customer who wants to use our service must create a user “mirror” on their server that we will use to connect to their server:

$ sudo adduser mirror
$ sudo adduser mirror www-data
$ sudo -u mirror mkdir /home/mirror/.ssh/

On our backup server we will run the following to add the ssh key pair of mirror@example.com to the authorized_keys of mirror@customersite.com:

$ sudo -u mirror ssh-copy-id -i ~/.ssh/id_rsa.pub mirror@customersite.com

The customer must also have a daily snapshot cron job (Making a snapshot of a Lino database) and communicate us the full path of the snapshot file(s) they want us to backup.

Setting up the backup server¶

In the following examples we assume that the service is to be running on your server example.com. Here is how we configured that server.

On the backup server, we create a user named “mirror” and a ssh key pair:

$ sudo adduser -d /mnt/disk/mirror/ mirror
$ sudo -u mirror ssh-keygen -t rsa -b 4096 -C "mirror@example.com"

By default, this will generate the ssh key file in /home/you/.ssh/id_rsa. When the prompt ask for where to store the key, we need to choose the home directory of the mirror user:

$ Enter file in which to save the key (/home/hamza/.ssh/id_rsa): /mnt/disk/mirror/.ssh/id_rsa

Create an executable file collect_snapshots.sh with this content:

#/bin/bash
# designed to run as cron job
set -e
TARGET=/mnt/disk/mirror/snapshots

# one rsync for each customer:
echo customer1
rsync --times --progress mirror@customer1:/customer1/path/to/snapshot.zip $TARGET/snapshots/customer1/
echo customer2
rsync --times --progress mirror@customer2:/customer2/path/to/snapshot.zip $TARGET/snapshots/customer2/

Add a daily cron job in /etc/cron.daily:

#!/bin/sh
sudo -u mirror /mnt/disk/mirror/collect_snapshots.sh > /dev/null

If we are using monit, we can add a check about old snapshots (more than one day):

#/bin/bash
# designed to run as cron job
set -e
TARGET=/mnt/disk/mirror/snapshots
if [[ $(find $TARGET -mtime +1 -print) ]]; then
  echo "File $filename exists and is older than one day"
fi