Skip to main content

Create and restore external backups of virtual machines with libvirt

A common need for deployments in production, is to have the possibility of taking backups of your working virtual machines, and export them to some external storage.
Although libvirt offers the possibility of taking snapshots and restore them, those snapshots are intended to be managed locally, and are lost when you destroy your virtual machines.
There may be the need to just trash all your environment, and re-create the virtual machines from an external backup, so this article offers a procedure to achieve it.

First step, create an external snapshot

So the first step will be taking an snapshot from your running vm. The best way to take an isolated backup is using blockcopy virsh command. So, how to proceed?

1. First you need to extract all the disks that your vm has. This can be achieved with domblklist command: 
DISK_NAME=$(virsh domblklist {{domain}} --details | grep 'disk' | awk '{print $3}')

This will extract the name of the device that the vm is using (vda, hda, etc...)

2. Second step will be to backup the xml of the virtual machine, because we will need to undefine it on next steps. So let's take the backup *: 
virsh dumpxml --inactive {{domain}} > /tmp/domain_backup.xml

3. Once we have the xml backup, let's undefine the vm temporarily:
virsh undefine {{ domain }}

4. Now it's time to take the backup. We are going to do it for each of the disks defined in our virtual machine:
virsh blockcopy {{domain}} $DISK_NAME /path/to/backups/{{domain}}_backup.qcow2 --wait --verbose --finish

Do it for all the vms and disks that you want to backup, and store on a safe place.

5. Define the VM again, so it goes up and running:
virsh define {{ domain }}

* You can store this xml dump also in the backups directory, so you could recreate the vm in the future with the same exact content.

Second step, consume the snapshot

Creating a new virtual machine using this snapshot is so easy. You just need to use the qcow2 that we created on the backup, as a path for the new created vm. Do it for all the disks. As a sample:
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/path/to/backups/{{ domain }}_backup.qcow2'/>
      <target dev='${DISK_NAME}' bus='ide'/>
      <alias name='ide0-0-0'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>


So this method provides a simple way to preserve the state of your vms, either for backup or for accelerating your testing by reusing vms on a known and good status.

Comments

  1. Or you could just use the "easy button" download Trilio and empower your admin and tenants via Horizon to manage their own environments, keep synthetic fulls in any storage environment, and recover to any point in time with just 1-click :)

    ReplyDelete
  2. oops...meant to add this
    www.trilio.io

    ReplyDelete

Post a Comment

Popular posts from this blog

Setup an NFS client provisioner in Kubernetes

Setup an NFS client provisioner in Kubernetes One of the most common needs when deploying Kubernetes is the ability to use shared storage. While there are several options available, one of the most commons and easier to setup is to use an NFS server.
This post will explain how to setup a dynamic NFS client provisioner on Kubernetes, relying on an existing NFS server on your systems.
Step 1. Setup an NFS server (sample for CentOS) First thing you will need, of course, is to have an NFS server. This can be easily achieved with some easy steps:

Install nfs package: yum install -y nfs-utils Enable and start nfs service and rpcbind:
systemctl enable rpcbind
systemctl enable nfs-server
systemctl start rpcbind
systemctl start nfs-server
Create the directory that will be shared by NFS, and change the permissions:
mkdir /var/nfsshare
chmod -R 755 /var/nfsshare
chown nfsnobody:nfsnobody /var/nfsshare
 Share the NFS directory over the network, creating the /etc/exports file:
vi /etc/exports
/var/nfsshare …

How to deploy TripleO Queens without external network

TripleO Queens has an interesting feature that is called 'composable networks'. It allows to deploy Openstack with the choice of networks that you want, depending on your environment. Please see: https://docs.openstack.org/tripleo-docs/latest/install/advanced_deployment/custom_networks.html

By default, the following networks are defined:
StorageStorage ManagementInternal ApiTenantManagementExternal The external network allows to reach the endpoints externally, and also to define networks to reach the vms externally as well. But to have that, it is needed to have a network with external access, routable, on your lab. Not all labs have it, specially for CI environments, so it may be useful to deploy without it, and just have internal access to endpoints and vms. In this blogpost i'm just going to explain how to achieve it.

First make a copy of your original tripleo-heat-templates, to another directory /home/stack/working-templates, and edit the following files:
network_data.…

Build and use security hardened images with TripleO

Starting to apply since Pike Concept of security hardened images Normally the images used for overcloud deployment in TripleO are not security hardened. It means, the images lack all the extra security measures needed to accomplish with ANSSI requirements. These extra measures are needed to deploy TripleO in environments where security is an important feature.
The following recommendations are given to accomplish with security guidelines:
ensure that /tmp is mounted on a separate volume or partition, and that it is mounted with rw,nosuid,nodev,noexec,relatime flagsensure that /var, /var/log and /var/log/audit are mounted on separates volumes or partitions, and that are mounted with rw,relatime flags.ensure that /home is mounted on a separate partition or volume, and that it is mounted with rw,nodev,relatime flags.include extra kernel boot flag to enable auditing: add audit=1 to GRUB_CMDLINE_LINUX settingdisable kernel support for USB via bootloader configuration: add nousb to GRUB_CMD…