How to Affordably Back Up a Linux Server with Duplicati and Backblaze B2

Create a Backblaze account, if you don't already have one.

Add your credit card details.

Create a new bucket and put a meaningful name, leaving all other options as they are.
I usually name my buckets: [customer]-[servername]-backup. So if the server is owned by Acme Inc. and the server name is nl-1.srv.example.net - the bucket name will become acme-nl1srvexamplenet-backup. This helps to orient and avoids colliding with other bucket names on services where they have to be unique. However, this is highly opinionated, so feel free to name your bucket according to your own preferences.

Create a new application key and allow access to the bucket you created
I would name it, following this structure: [customer]-[servername]-backup-key.

Copy your newly created application key's keyID and applicationKey as we'll need them later.

Populate /root/.my.cnf with your MySQL root username and password:

[client]
user=root
password=YourRootPassword

Restrict access chmod og= /root/.my.cnf

Create the scripts directory sudo mkdir /root/scripts

Create and populate /root/scripts/mysqlbackup.sh:

#!/bin/sh

# -------------------
# MySQL Backup Script
# Copyright (c) 2023-2024 Grigor Yosifov <grigor@grigor.com>
# -------------------
# Crontab Settings:
# To set up a daily cronjob for this script:
# 1. Run `crontab -e` to edit the cron jobs.
# 2. Add the following line:
# 13 0 * * * /root/scripts/mysqlbackup.sh
# This schedules the script to run daily at 00:13.
# -------------------

# Script Configuration
RETENTION_DAYS=30
BACKUP_DIR="/root/backups/mysql"
MYSQL_HOST="localhost"

### Paths ###
DATE=$(date +"%Y-%m-%d")
MYSQL_PATH="$(which mysql)"
MYSQLDUMP_PATH="$(which mysqldump)"
BZIP_PATH="$(which bzip2)"

mkdir -p "$BACKUP_DIR"

### Start MySQL Backup ###
DATABASES="$($MYSQL_PATH -h $MYSQL_HOST -Bse 'show databases')"

for db in $DATABASES; do
    if [ "$db" != "information_schema" ] && [ "$db" != "performance_schema" ]; then
        BACKUP_FILE="${BACKUP_DIR}/${DATE}-${db}.sql.bz2"
        $MYSQLDUMP_PATH --single-transaction --skip-lock-tables -h $MYSQL_HOST $db | $BZIP_PATH > "$BACKUP_FILE"

        # Keep only the latest RETENTION_DAYS backups and delete the rest
        ls "${BACKUP_DIR}"/*"-${db}.sql.bz2" | sort -r | tail -n +$((RETENTION_DAYS + 1)) | xargs rm -f
    fi
done

Make it executable: chmod +x /root/scripts/mysqlbackup.sh

Verify that it works, executing: /root/scripts/mysqlbackup.sh and check whether backup files were successfully created: ls -l /root/backups/mysql/

Set up a daily cronjob for this script:

1. Run crontab -e to edit the cron jobs.

2. Add the following line:

   15 0 * * * /root/scripts/mysqlbackup.sh
   

   To schedule the script to run daily at 00:15.

Create an empty file /root/.forward and add your email address to receive any errors for the root user.

1. Test if it works: echo test | sendmail root
2. If it doesn't, check mail logs for more information: tail -100 /var/log/mail.log

If you don't have the latest version of Mono, install it as per the instructions for your Linux distribution from the official Mono download page
Important: Make sure to install the "mono-complete" package to avoid certain warnings and error messages in Duplicati that might otherwise appear days or weeks after you start using it.

Download and install the latest version of Duplicati for Linux as described in the Duplicati 2 User's Manual but before you start the service (last step), configure an SSL certificate as follows, as otherwise, the unencrypted keys for your backup cloud storage and your encryption keys will be transferred in plain text over the internet!
There are two ways to configure an SSL certificate, where the first one is the preferred way:

• (if you have a web server) A valid SSL through a reverse proxy for nginx or Apache
  This is preferred, because you can easily configure LetsEncrypt and additional security through the web server, like HTTP auth, IP whitelist, etc.

  1. Assuming you have a running web server with a valid SSL on your hostname (if you don't – check Certbot as this is the recommended by Let's Encrypt way for easy SSL setup on any web server):

     • (for nginx) Add this to the SSL-enabled server configuration block:

     server {
     		listen 443 ssl;
             #...
             
             # Duplicati: redirects /duplicati to /duplicati/
             location /duplicati {
                     return 301 $scheme://$host/duplicati/;
             }
             # Duplicati: reverse proxy
             location ^~ /duplicati/ {
                     proxy_pass http://127.0.0.1:8200;
                     proxy_redirect / /duplicati/;
                     rewrite /duplicati(.*) $1 break;
             }
             #...
     }
     

     Restart nginx.

     • (for Apache 2) Add this to the SSL-enabled virtual host configuration:

     <VirtualHost *:443>
     	#...
     	
     	# Duplicati: redirects /duplicati to /duplicati/
     	RewriteEngine On
     	RewriteRule ^/duplicati$ https://%{HTTP_HOST}/duplicati/ [R=301,L]					
     	# Duplicati: allows restore to work through the reverse proxy
     	AllowEncodedSlashes On
     	
     	# Duplicati: reverse proxy
     	<Location /duplicati/>
     		ProxyPass http://127.0.0.1:8200/
     		ProxyPassReverse http://127.0.0.1:8200/
     		ProxyPreserveHost On
     		Order allow,deny
     		Allow from all
     	</Location>
     	#...
     </VirtualHost>
     

     Restart apache2.

  2. Open /etc/default/duplicati and replace the entire line of DAEMON_OPTS=… with

     DAEMON_OPTS=" --webservice-allowed-hostnames=nl-1.srv.example.net"
     

     Replace nl-1.srv.example.net with your server hostname.

• (if you don't have a web server) A self-signed SSL certificate directly through the Duplicati configuration

  1. Generate the SSL certificate:

     sudo sh -c 'mkdir -p /root/.config/Duplicati/ssl && chmod -R og= /root/.config/Duplicati'
     
     # Replace "nl-1.srv.example.net" with your server hostname
     sudo openssl req -x509 -newkey rsa:4096 -keyout /root/.config/Duplicati/ssl/key.pem -out /root/.config/Duplicati/ssl/cert.pem -sha256 -days 3650 -nodes -subj "/CN=nl-1.srv.example.net"
     
     # Replace "nl-1.srv.example.net" with your server hostname
     sudo openssl pkcs12 -export -out /root/.config/Duplicati/ssl/nl-1.srv.example.net.pfx -inkey /root/.config/Duplicati/ssl/key.pem -in /root/.config/Duplicati/ssl/cert.pem -passout pass:
     

  2. Open /etc/default/duplicati and replace the entire line of DAEMON_OPTS=… with

     DAEMON_OPTS="--webservice-interface=any --webservice-port=8200 --webservice-allowed-hostnames=nl-1.srv.example.net --webservice-sslcertificatefile=/root/.config/Duplicati/ssl/nl-1.srv.example.net.pfx"
     

     Replace both nl-1.srv.example.net with your server hostname.

Once started, you can now access the Duplicati web UI: http://nl-1.srv.example.net:8200

Add a new backup, setting the following fields on the configuration tabs:

1. "General" tab:

   • Name: Backblaze Backup
   • Passphrase - set up a good encryption password - I'd use a 64 characters random string

2. "Destination" tab

   • Storage Type: B2 Cloud Storage
   • Bucket name: the one you created earlier (e.g., acme-nl1srvexamplenet-backup)
   • B2 Application ID: the keyID that you copied earlier.
   • B2 Application Key: the applicationKey that you copied earlier.
     Now test your connection, and continue to the next step if it's successful.

3. "Source Data" tab

   • Source data: choose what folders you want to backup, I usually choose /etc, /home, /root, /var/spool/cron
   • Filters: expand Filters, then click on the three dots > "Edit as text"

     

     
     This is the list I use, feel free to modify according to your needs:

   -*.log
   -access-logs/*
   -*/backupbuddy_backups/*
   -*/cache/smarty/*
   -.cagefs
   -.cagefs*
   -*/com_akeeba/backup/*
   -*/core.[0-9]*
   -.cpan
   -.cpanel/caches
   -.cpanel/datastore
   -.cpanel/*.sock
   -.cpcpan
   -*/error_log
   -logs/*
   -tmp/*
   -.MirrorSearch
   -public_ftp/*
   -public_html/cache/*
   -softaculous_backups/*
   -.sqmailattach
   -*/var/amasty_fpc/*
   -*/var/backups/*
   -*/var/cache/*
   -*/var/debug/*
   -*/var/export/*
   -*/var/import/*
   -*/var/log/*
   -*/var/report/*
   -*/var/session/*
   -*/var/tmp/*
   -*/wp-content/cache/*
   -*/wp-content/uploads/wpcf7_captcha/*
   -*/wp-content/widget-cache/*
   -*.wpress
   -*/wptsc-cachedir/*
   -*/.wysiwygPro_*
   -/root/.config/Duplicati/
   

4. "Schedule" tab

   • Choose a time of day for the backups – usually when your server is less loaded (e.g., 2 am)

5. "Options" tab

   • Backup retention: Custom backup retention
   • Configure the custom retention field, e.g., 30D:1D,1Y:1M if you want to keep one backup for each of the next 30 days, and one for each of the next 12 months

"Run now" your backup and monitor it from time to time. If it stops, re-run until it completes successfully (e.g., if a connectivity issue with Backblaze B2 occurs, it will result in an error. Re-running the backup will resume the progress from where it stopped).

Test and verify that the restoration process works!