virt-back 0.2.3

virt-back: A backup utility for QEMU, KVM, XEN, and Virtualbox guests

A backup utility for QEMU, KVM, XEN, and Virtualbox guests.

Virt-back is a python application that uses the libvirt api to safely shutdown, gzip, and restart guests. The backup process logs to syslog for auditing and virt-back works great with cron for scheduling outages. Virt-back has been placed in the public domain and the latest version may be downloaded here:

https://git.unturf.com/python/virt-back

usage

root@guile[/mnt/downloads/virt-back]# ./virt-back --help
Usage: virt-back [options]

A backup utility for QEMU, KVM, XEN, and Virtualbox guests. Virt-back is a
python application that uses the libvirt api to safely  shutdown, gzip, and
restart guests.  The backup process logs to syslog for auditing and virt-back
works great with cron for scheduling outages. Virt-back has been placed in the
public domain and  the latest version may be downloaded here:
https://git.unturf.com/python/virt-back

Options:
  -h, --help            show this help message and exit
  -q, --quiet           prevent output to stdout
  -d, --date            append date to tar filename [default: no date]
  -g, --no-gzip         do not gzip the resulting tar file
  -a amount, --retention=amount
                        backups to retain [default: 3]
  -p 'PATH', --path='PATH'
                        backup path [default: '/KVMBACK']
  -u 'URI', --uri='URI'
                        optional hypervisor uri

  Actions for info testing:
    These options display info or test a list of guests.

    -i, --info          info/test a list of guests (space delimited dom names)
    --info-all          attempt to show info on ALL guests

  Actions for a list of dom names:
    WARNING:  These options WILL bring down guests!

    -b, --backup        backup a list of guests (space delimited dom names)
    -r, --reboot        reboot a list of guests (space delimited dom names)
    -s, --shutdown      shutdown a list of guests (space delimited dom names)
    -c, --create        start a list of guests (space delimited dom names)

  Actions for all doms:
    WARNING:  These options WILL bring down ALL guests!

    --backup-all        attempt to shutdown, backup, and start ALL guests
    --reboot-all        attempt to shutdown and then start ALL guests
    --shutdown-all      attempt to shutdown ALL guests
    --create-all        attempt to start ALL guests

Dependencies

Before installing virt-back, you need to ensure that the necessary development libraries for libvirt are installed on your system. These libraries are required for the libvirt-python package, which virt-back depends on.

Fedora/RedHat

On Fedora or RedHat-based systems, you can install the libvirt-devel package using dnf:

sudo dnf install libvirt-devel

Ubuntu/Debian

On Ubuntu or Debian-based systems, you can install the libvirt-dev package using apt-get:

sudo apt-get install libvirt-dev

Installing virt-back

Once the necessary development libraries are installed, you can install virt-back using pip:

pip install virt-back

This will install virt-back along with its dependencies, including libvirt-python.

How to backup zfs snapshot all KVM instances on a TrueNAS Scale,

root@guile[/mnt/downloads/virt-back]# ./virt-back -u "qemu+unix:///system?socket=/run/truenas_libvirt/libvirt-sock" --backup-all --path /mnt/personal/backup/virt-back --no-gzip --retention 5

shutdown: invoking shutdown on 1_akuma
shutdown: waited 0 seconds for 1_akuma to shut off
backup: invoking backup for 1_akuma
backup: checking if /dev/zvol/downloads/akuma-tfjpo7 is a ZFS dataset
backup: downloads/akuma-tfjpo7 is a ZFS dataset
backup: creating ZFS snapshot downloads/akuma-tfjpo7@backup-2024-07-07-2 for 1_akuma
backup: sending ZFS snapshot downloads/akuma-tfjpo7@backup-2024-07-07-2 to /mnt/personal/backup/virt-back/1_akuma-2024-07-07.zfs for 1_akuma
backup: skipping ISO file /mnt/downloads/iso/ubuntu-24.04-live-server-amd64.iso for 1_akuma
create: invoking create on 1_akuma
backup: rotating backup files for 1_akuma
backup: archiving files for 1_akuma to /mnt/personal/backup/virt-back/1_akuma.tar
backup: archiving /mnt/personal/backup/virt-back/1_akuma.xml for 1_akuma
backup: checking if /dev/zvol/downloads/akuma-tfjpo7 is a ZFS dataset
backup: downloads/akuma-tfjpo7 is a ZFS dataset
backup: archiving /mnt/personal/backup/virt-back/1_akuma-2024-07-07.zfs for 1_akuma
backup: finished backup for 1_akuma

Restoring from a ZFS Backup

This section explains how to restore a KVM instance from a ZFS backup using the virt-back utility. The process involves extracting the backup archive, restoring the ZFS snapshot, and creating a new VM in TrueNAS Scale using the restored ZFS volume.

Step-by-Step Restore Process

1. Extract the Backup Archive: Extract the tar archive to get the ZFS snapshot file and the XML configuration file.
2. Restore the ZFS Snapshot to a New Dataset: Use the zfs receive command to restore the ZFS snapshot to a new dataset.
3. Create a New VM in TrueNAS Scale: Use the TrueNAS Scale UI to create a new VM and point it to the restored ZFS volume.

Detailed Steps

1. Extract the Backup Archive

First, extract the tar archive to get the ZFS snapshot file and the XML configuration file. Use the --strip-components option to remove the leading directory components if necessary.

tar -xvf /mnt/personal/backup/virt-back/1_akuma.tar --strip-components=4 -C /mnt/personal/backup/virt-back

This command will extract the files directly to the /mnt/personal/backup/virt-back directory, removing the leading directory components.

2. Restore the ZFS Snapshot to a New Dataset

Use the zfs receive command to restore the ZFS snapshot to a new dataset. Assuming the extracted ZFS snapshot file is named 1_akuma-2024-07-07.zfs:

zfs receive -F downloads/akuma-tfjpo7-restored < /mnt/personal/backup/virt-back/1_akuma-2024-07-07.zfs

This command will restore the ZFS snapshot to the downloads/akuma-tfjpo7-restored dataset.

3. Create a New VM in TrueNAS Scale

1. Open TrueNAS Scale UI: Log in to the TrueNAS Scale web interface.
2. Navigate to Virtual Machines: Go to the "Virtual Machines" section.
3. Create a New VM:
   • Click on "Add" to create a new VM.
   • Fill in the necessary details for the new VM (e.g., name, CPU, memory).
4. Attach the Restored ZFS Volume:
   • In the "Disks" section, add a new disk.
   • Select "Existing Zvol" and choose the restored ZFS volume (downloads/akuma-tfjpo7-restored).
5. Complete the VM Creation: Finish the VM creation process by following the remaining steps in the UI.

Summary

By following these steps, you can restore the ZFS snapshot and reattach it to a new VM using the TrueNAS Scale UI. This process involves extracting the backup archive, restoring the ZFS snapshot to a new dataset, and creating a new VM in TrueNAS Scale, pointing it to the restored ZFS volume. This approach ensures that the original dataset remains unaffected and allows you to easily restore and reattach your KVM instances. It's similar to cloning an existing instance except it's from a file backup so the machine will have all the attributes of the clone don't start them both at the same time because that would have IP address overlaps etc.