Run BorgBackup automatically on Linux

Posted on February 18, 2020

Introduction

Most people will have some files they want to keep secret. In order to keep the files secret, it is recommended to keep them in a encrypted partition. One popular method for encrypting a files is eCryptfs.

To prevent important files from being lost, a backup could be taken of the ~/.Private folder, which is where all of the encrypted files exist. This is sufficient for recovering the files, as long as you can setup the eCryptfs partitions correctly again. However, I want to backup specific files from the unencrypted ~/Private partition just in case I want to quickly roll back a specific file.

The problem is, how can I start the backup only when the ~/Private folder is mounted and unencrypted files are available? I will describe my solution to the problem which uses BorgBackup, borgmatic, systemd and some bash scripting.

BorgBackup

The first step is to get a BorgBackup repository working.

Read the docs

If just getting started, I recommend reading through the BorgBackup documentation. For our purposes, you will need to know how to initialize a BorgBackup repository so backups can be stored somewhere.

SSH repository

I use an SSH repository to a server. Because the access to the server is managed by an SSH key file, a password prompt can be avoided to make it easier to do an automated backup.

My BorgBackup init command looked something like this: borg init -e repokey-blake2 david@myserver:backup_dir.

Use a strong passphrase

If you are backing up unencrypted files, you’ll want to make sure to use a strong passphrase so that no one with access to the backup repository can view the files. The passphrase will be used every time BorgBackup is ran using the environment variable BORG_PASSPHRASE.

Remember the passphrase

The passphrase is needed if you ever need to recover the files. Put the passphrase in a location separate from the files being backed up or the location of the encrypted backup files. I recommend a password manager that is ideally backed up a different way, such as Bitwarden or a replicated Keepass database.

I also backed up the borg init command just in case the encryption algorithm and server directory I was using was lost.

Borg helper scripts

I never remember the exact arguments to use with BorgBackup to initiate backups and list my backups with, so I created a simple script.

I will sometimes use this script to list files backed up using the following commands:

$ ./borg.bash list
myserver-2020-01-30T09:13:05.446876       Thu, 2020-01-30 09:13:06 [4...1]
myserver-2020-02-04T06:48:15.991816       Tue, 2020-02-04 06:48:16 [2...0]
myserver-2020-02-12T09:47:39.618958       Wed, 2020-02-12 09:47:40 [0...3]

$ ./borg.bash list ::myserver-2020-01-30T09:13:05.446876
-rw-r--r-- david  david      3115 Wed, 2020-01-29 10:54:59 home/david/Private/file1
drwxrwxrwx david  david         0 Wed, 2018-12-26 18:59:58 home/david/Private/file2
-rw-r--r-- david  david        67 Sat, 2017-04-29 09:47:41 home/david/Private/note.txt

I rely on borgmatic to do the actual backup command, since a backup involves listing many folders and files.

WARNING: Storing the passphrase in a script is a security risk! Consider keeping scripts with passphrases in an encrypted volume.

Borgmatic

Setup a borgmatic configuration to easily run borgmatic. I personally never run the borg command directly to do backups. I first create a borgmatic configuration and always us the borgmatic command to launch borg for me.

More docs

Like BorgBackup, I recommend referring to the documentation for borgmatic. Borgmatic has a lot of options for how the configuration file can be set. First, a configuration file needs to be generated with generate-borgmatic-config.

Some important sections of the borgmatic configuration file are source_directories, repositories, encryption_passphrase, and retention. My borgmatic-config.yaml looks like this (without a lot of the comments):

# Where to look for files to backup, and where to store those backups. See
# https://borgbackup.readthedocs.io/en/stable/quickstart.html and
# https://borgbackup.readthedocs.io/en/stable/usage.html#borg-create for details.
location:
    # List of source directories to backup (required). Globs and tildes are expanded.
    source_directories:
        - ~/.gnupg
        - ~/.config/systemd/user
        - ~/Private/borg
        - ~/Private/other-important-files

    # Paths to local or remote repositories (required). Tildes are expanded. Multiple
    # repositories are backed up to in sequence. See ssh_command for SSH options like
    # identity file or port.
    repositories:
        - david@myserver:backup_dir

# Repository storage options. See
# https://borgbackup.readthedocs.io/en/stable/usage.html#borg-create and
# https://borgbackup.readthedocs.io/en/stable/usage/general.html#environment-variables for
# details.
storage:
    encryption_passphrase: "my-secure-passphrase"

# Retention policy for how many backups to keep in each category. See
# https://borgbackup.readthedocs.org/en/stable/usage.html#borg-prune for details.
# At least one of the "keep" options is required for pruning to work. See
# https://torsion.org/borgmatic/docs/how-to/deal-with-very-large-backups/
# if you'd like to skip pruning entirely.
retention:
    # Keep all archives within this time interval.
    keep_within: 3H
    # keep_secondly: 60
    # keep_minutely: 60
    keep_hourly: 24
    keep_daily: 7
    keep_weekly: 4
    keep_monthly: 6
    keep_yearly: 5

hooks:
    before_backup:
        - echo "Starting a backup."
    after_backup:
        - echo "Created a backup."
    on_error:
        - echo "Error while creating a backup or running a backup hook."

Usage

After setting up the configuration file, using borgmatic to run borg is as easy as specifying the configuration file with the -c switch. For example: borgmatic -c borgmatic-config.yaml list.

Helper script

Again, I try to make things a little bit easier for myself by creating a small helper script for borgmatic. I don’t even need to remember to include the configuration flag. Here is my helper script where I can run borgmatic with ./borgmatic.bash list.

#!/bin/bash

# Helper script to run borgmatic commands
borgmatic -v 1 -c borgmatic-config.yaml "$@"

Time for a backup

At this point, since all of the source files and repositories have been specified in the borgmatic-config.yaml, a backup can be taken. ./borgmatic.bash should be all that is needed to take a backup.

My directory containing my helper scripts and borgmatic configuration file now look like this:

$ tree
.
├── borg.bash
├── borgmatic.bash
└── borgmatic-config.yaml

0 directories, 3 files

If you are not interesting in an automatic backup then you can stop here. I recommend an automatic backup however, so you will have a backup ready if you need one. It is easy to forget to do regular backups manually.

Systemd timer

I decided to automate the borgmatic backup with Systemd. A user systemd timer and service can be created in the ~/.config/systemd/user directory to run the backup daily.

My ~/.config/systemd/user directory looks like this after creating three necessary files:

/home/david/.config/systemd/user/
├── borgmatic.service
├── borgmatic.timer
└── timers.target.wants
    ├── borgmatic.timer -> /home/david/.config/systemd/user/borgmatic.timer
    └── vdirsyncer.timer -> /usr/lib/systemd/user/vdirsyncer.timer

borgmatic.service describes how to run the backup.

[Unit]
Description=borgmatic backup
Wants=network-online.target
After=network-online.target
ConditionACPower=true

[Service]
Type=oneshot

# Lower CPU and I/O priority.
Nice=19
CPUSchedulingPolicy=batch
IOSchedulingClass=best-effort
IOSchedulingPriority=7
IOWeight=100

Restart=no
LogRateLimitIntervalSec=0

# Delay start to prevent backups running during boot.
ExecStartPre=sleep 1m
# Test for private files. Should cause failure config file doesn't exist
ExecStartPre=/usr/bin/test -f /home/david/Private/borg/borgmatic-config.yaml

ExecStart=systemd-inhibit --who="david" --why="Prevent interrupting scheduled backup" /usr/bin/borgmatic --syslog-verbosity 1 -c /home/david/Private/borg/borgmatic-config.yaml

# Restart on failure. Keep trying to create backup.
RestartSec=10m
Restart=on-failure

borgmatic.timer is a scheduler for when to run the backup.

[Unit]
Description=Run borgmatic backup

[Timer]
OnCalendar=daily
Persistent=true

[Install]
WantedBy=timers.target

timers.target.wants is a directory created by systemd.

Of course you’ll want to change instances of david to your username.

Test service

First, it is important to see if the service is setup correctly. Scan for new user unit files with systemctl --user daemon-reload.

Then run the service file with systemctl --user start borgmatic.service.

journalctl --user -n 200 -f -u borgmatic.service should show the text output of the backup.

Enable timer

Since the service file should now be working, enable the timer so the service is schedule regularly. Run systemctl enable --now borgmatic.timer to enable the timer.

Sanity check

How to check if everything is working.

List backups

The easiest thing to do is list backups and then list files backed up for a specific backup. Here is now:

./borgmatic.bash list
david@bison.parrish:backup_bar: Listing archives
myserver-2020-01-19T11:58:43.835270       Sun, 2020-01-19 11:58:44 [7...6]
myserver-2020-01-19T12:01:09.110944       Sun, 2020-01-19 12:01:10 [1...f]
myserver-2020-01-27T07:43:41.464375       Mon, 2020-01-27 07:43:42 [8...9]
myserver-2020-01-30T09:13:05.446876       Thu, 2020-01-30 09:13:06 [4...1]
myserver-2020-02-04T06:48:15.991816       Tue, 2020-02-04 06:48:16 [2...0]
myserver-2020-02-12T09:47:39.618958       Wed, 2020-02-12 09:47:40 [0...3]
myserver-2020-02-12T10:47:58.633934       Wed, 2020-02-12 10:47:59 [3...e]
myserver-2020-02-14T11:47:16.646835       Fri, 2020-02-14 11:47:17 [6...8]
myserver-2020-02-15T07:17:20.876995       Sat, 2020-02-15 07:17:21 [0...8]
myserver-2020-02-17T09:26:10.644048       Mon, 2020-02-17 09:26:11 [f...8]
myserver-2020-02-18T08:12:29.699794       Tue, 2020-02-18 08:12:30 [b...3]
myserver-2020-02-18T10:05:44.636999       Tue, 2020-02-18 10:05:45 [d...8]
myserver-2020-02-18T10:22:29.626931       Tue, 2020-02-18 10:22:30 [5...f]

summary:
/home/david/Private/borg/borgmatic-config.yaml: Successfully ran configuration file

$ ./borg.bash list ::myserver-2020-01-30T09:13:05.446876
-rw-r--r-- david  david      3115 Wed, 2020-01-29 10:54:59 home/david/Private/file1
drwxrwxrwx david  david         0 Wed, 2018-12-26 18:59:58 home/david/Private/file2
-rw-r--r-- david  david        67 Sat, 2017-04-29 09:47:41 home/david/Private/note.txt

If you see the backups running every day and your files are in the backup, then you should be all good!

Show output

View output from systemctl and jounalctl for more information on the running backups.

systemctl --user status borgmatic.service to see the latest status of the backup.

journalctl --user -n 100 -u borgmatic.service to get line-by-line output from the last backup. Add a -f flag to “follow” the output in as the backup is taking place.

Conclusion

Hopefully this post helps you follow along with a backup configuration which works for me. Please follow the references listed below for more information on setting up a backup for yourself.

References

Modified: February 18, 2020 - 03:17:06 PM