terraform-libvirt-kubernetes

A small project describing how to use terraform to deploy infrastructure for Kubernetes on KVM.

Install the necessary components and dependencies

I am writing this guide 08.2019, versions of some components could not coincide with the current ones. All commands run as root.

Operating system

For this project, I used CentOS operating system on hardware and virtual machines.

• CentOS-7-x86_64-Minimal-1810 for bare metal
• CentOS-7-x86_64-GenericCloud-1901 for virtual machines

Check CPU virtualization

First check if your CPU supports hardware virtualization

cat /proc/cpuinfo | egrep "(vmx|svm)"

If the command does not return anything, virtualization is not supported on the server or it is disabled in the BIOS settings. KVM itself can be put on such a server, but when we try to enter the hypervisor management command, we will get the error "WARNING KVM acceleration not available, using 'qemu'".

Install libvirt and virsh

yum install -y qemu-kvm libvirt virt-install

• qemu-kvm - hypervisor;
• libvirt - virtualization management library;
• virt-install - utility for managing virtual machines.

Allow autorun:

systemctl enable libvirtd

Launch KVM:

systemctl start libvirtd

Network configuration

Install the package to work with bridge:

yum install -y bridge-utils

Сheck the real network interface with the configured IP address

ip a

Edit the settings of the real adapter:

vi /etc/sysconfig/network-scripts/ifcfg-eth0

Need to get something like this:

TYPE=Ethernet
DEVICE=eth0
#IPADDR=192.168.1.100
#PREFIX=24
#GATEWAY=192.168.1.1
#DNS1=8.8.8.8
#DNS2=8.8.4.4
ONBOOT=yes
BOOTPROTO=none
BRIDGE=br0

Create an interface for the network bridge:

vi /etc/sysconfig/network-scripts/ifcfg-br0

Need to get something like this:

DEVICE=br0
TYPE=Bridge
ONBOOT=yes
BOOTPROTO=static
IPADDR=192.168.1.100
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
DNS1=8.8.8.8
DNS2=8.8.4.4

Restart the network:

systemctl restart network

Restart libvirtd:

systemctl restart libvirtd

Install terraform

Ensure wget and unzip are installed

yum install -y wget unzip

Then download the terraform archive

wget https://releases.hashicorp.com/terraform/0.11.10/terraform_0.11.10_linux_amd64.zip
unzip terraform_0.11.10_linux_amd64.zip

This will create a terraform binary file on your working directory. Move this file to the directory/usr/local/bin

mv terraform /usr/local/bin/

Confirm the version installed

terraform -v

Install Terraform KVM provider

Terraform has a number of officially supported providers available for use. Unfortunately, KVM is not in the list. I will use the Terraform KVM provider

wget https://github.com/dmacvicar/terraform-provider-libvirt/releases/download/v0.5.1/terraform-provider-libvirt-0.5.1.CentOS_7.x86_64.tar.gz
tar xvf terraform-provider-libvirt-0.5.1.CentOS_7.x86_64.tar.gz
mv terraform-provider-libvirt ~/.terraform.d/plugins/

Check that libvirt daemon 1.2.14 or newer is running on the hypervisor

yum info libvirt

Component versions

• OS - CentOS Linux release 7.6.1810 (Core)
• Libvirt - Version : 4.5.0
• Terraform - v0.11.10
• terraform-provider-libvirt - 0.5.1.CentOS_7.x86_64

If all the necessary components and dependencies are installed, you can start writing the infrastructure as code

Terraform

Initialize a Terraform working directory

terraform init

Generate and show Terraform execution plan

terraform plan

Then build your Terraform infrastructure

terraform apply

Check your infrastructure use virsh

virsh list --all

You can destroy your Terraform infrastructure

terraform destroy

Creating virsh pool

Terraform v0.11.10 cannot create a storage pool from code. In this example I will use the virsh for create k8s-pool. "/kvm/images" is the path to a file system directory for storing image files. If this directory does not exist, virsh will create it.

virsh pool-define-as k8s-pool dir - - - - "/kvm/images"

Check storage pool

virsh pool-list --all

Build and start k8s-pool

virsh pool-build k8s-pool
virsh pool-start k8s-pool

Enable autostart to start the pool after restarting the machine.

virsh pool-autostart k8s-pool