Book Image

KVM Virtualization Cookbook

Book Image

KVM Virtualization Cookbook

Overview of this book

Virtualization technologies such as KVM allow for better control over the available server resources, by deploying multiple virtual instances on the same physical host, or clusters of compute resources. With KVM it is possible to run various workloads in isolation with the hypervisor layer providing better tenant isolation and higher degree of security. This book will provide a deep dive into deploying KVM virtual machines using qemu and libvirt and will demonstrate practical examples on how to run, scale, monitor, migrate and backup such instances. You will also discover real production ready recipes on deploying KVM instances with OpenStack and how to programatically manage the life cycle of KVM virtual machines using Python. You will learn numerous tips and techniques which will help you deploy & plan the KVM infrastructure. Next, you will be introduced to the working of libvirt libraries and the iPython development environment. Finally, you will be able to tune your Linux kernel for high throughput and better performance. By the end of this book, you will gain all the knowledge needed to be an expert in working with the KVM virtualization infrastructure.

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Table of Contents (15 chapters)
Title Page
Title Page
Credits
Credits
About the Author
About the Author
About the Reviewer
About the Reviewer
www.PacktPub.com
www.PacktPub.com
Customer Feedback
Customer Feedback
Preface
Preface
Free Chapter
1
Getting Started with QEMU and KVM
Getting Started with QEMU and KVM
Introduction
Installing and configuring QEMU
Managing disk images with qemu-img
Preparing images for OS installation with qemu-nbd
Installing a custom OS on the image with debootstrap
Resizing an image
Using pre-existing images
Running virtual machines with qemu-system-*
Starting the QEMU VM with KVM support
Connecting to a running instance with VNC
2
Using libvirt to Manage KVM
Using libvirt to Manage KVM
Introduction
Installing and configuring libvirt
Defining KVM instances
Starting, stopping, and removing KVM instances
Inspecting and editing KVM configs
Building new KVM instances with virt-install and using the console
Managing CPU and memory resources in KVM
Attaching block devices to virtual machines
Sharing directories between a running VM and the host OS
Autostarting KVM instances
Working with storage pools
Managing volumes
Managing secrets
3
KVM Networking with libvirt
KVM Networking with libvirt
Introduction
The Linux bridge
The Open vSwitch
Configuring NAT forwarding network
Configuring bridged network
Configuring PCI passthrough network
Manipulating network interfaces
4
Migrating KVM Instances
Migrating KVM Instances
Introduction
Manual offline migration using an iSCSI storage pool
Manual offline migration using GlusterFS shared volumes
Online migration using the virsh command with shared storage
Offline migration using the virsh command and local image
Online migration using the virsh command and local image
5
Monitoring and Backup of KVM Virtual Machines
Monitoring and Backup of KVM Virtual Machines
Introduction
Resource usage collection with libvirt
Monitoring KVM instances with Sensu
Simple KVM backups with tar and rsync
Creating snapshots
Listing snapshots
Inspecting snapshots
Editing snapshots
Reverting snapshots
Deleting snapshots
6
Deploying KVM Instances with OpenStack
Deploying KVM Instances with OpenStack
Introduction
Preparing the host for the OpenStack deployment
Installing and configuring the OpenStack Keystone identity service
Installing and configuring the OpenStack Glance image service
Installing and configuring the OpenStack Nova compute service
Installing and configuring the OpenStack Neutron networking service
Building and inspecting KVM instances with OpenStack
Stopping KVM instances with OpenStack
Terminating KVM instances with OpenStack
7
Using Python to Build and Manage KVM Instances
Using Python to Build and Manage KVM Instances
Introduction
Installing and using the Python libvirt library
Defining KVM instances with Python
Starting, stopping, and deleting KVM instances with Python
Inspecting KVM instances with Python
Building a simple REST API server with libvirt and bottle
8
Kernel Tuning for KVM Performance
Kernel Tuning for KVM Performance
Introduction
Tuning the kernel for low I/O latency
Memory tuning for KVM guests
CPU performance options
NUMA tuning with libvirt
Tuning the kernel for network performance

Defining KVM instances with Python

In this recipe we are going to define a new KVM instance using the Python libvirt module we installed in the previous recipe. We are going to use a virtual environment and the iPython development tool for the following examples.

Getting ready

For this recipe we are going to need the following:

  • An Ubuntu host, with libvirt and QEMU installed and configured
  • The debian.img raw image file we built in the Installing custom OS on the image with debootstrap recipe from Chapter 1, Getting Started with QEMU and KVM
  • Python 2.7, the iPython tool, and the virtual environment we created in the Installing and using the Python libvirt library recipe in this chapter

How to do it...

To define a new KVM instance, using the Python libvirt module follow these instructions:

  1. In the iPython interpreter, import the libvirt module:
In [1]: import libvirt

In [2]:
  1. Create the instance definition string:
In [2]: xmlconfig = """
<domain type='kvm' id='1'>
 <name>kvm_python</name...
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