KVM Guest VM

Prerequisites

A KVM enabled host.
The Terraform CLI, version 1.0.8 or later.
Hashicorp tls provider vesion >= 3.1.0.
dmacvicar/libvirt provider version >= 0.6.12.
The git CLI.

Setup

Add the KVM guest VM details in to maint.tf file.

vi ./terraform/guest-vm-centos/maint.tf

module "centos-2" {
 source = "./modules/tf-module-kvm-guest-centos"

 guest_vm  = {
   "name"          = "centos-2"
   "dnsDomain"     = "kvm.local"
   "memoryMB"      = "4096"
   "vcpu"          = "4"
   "diskPool"      = "images"
   "network"       = "default"
   "imageSource"   = "https://cloud.centos.org/centos/8/x86_64/images/CentOS-8-GenericCloud-8.4.2105-20210603.0.x86_64.qcow2"
 }
}

Use the following commands to create the KVM guest VMs.

terraform init
terraform plan
terrafrm apply

Variables

The following are the variables used for this module.

Name	Type	Map Keys	Default	Description
guest_vm	Map	name	instance-1	Name of the guest VM.
		dnsDomain	kvm.local	FQDN for the guest VM.
		memoryMB	2048	Memory allocation for the guest VM in MB.
		vcpu	2	vCPU allocation for the guest vm.
		diskPool	vmpool	The KVM storage pool. If doesn't exists, needs to created before running this module.
		network	default	The KVM network VLAN for the guest VM.
		imageSource	< CentOS cloud image URL >	The CentOS cloud image URL.

Outputs

This module will provide the following outputs.

Output Name	Type	Description
ip	string	IP address of the KVM guest VM.

Troubleshooting

To check KVM guest VM

# virsh list --all

To check KVM guest IP

# virsh net-dhcp-leases default

Create NAT port forwarding to KVM guest VM

Setup qemu hooks

Create qemu file.

mkdir -p /etc/libvirt/hooks/qemu
chmod +x /etc/libvirt/hooks/qemu

Copy the shell script into newly created qemu file.

cp ./kvm-scripts/qemu-hooks.sh /etc/libvirt/hooks/qemu

Allow access from outside to the KVM guest

# vi /etc/libvirt/hooks/qemu

Add the follwoing line to the end of the file.

addForward <KVM gues VM name>  <KVM host network interface> <KVM host IP address> <Listening port on KVM host>  virbr0 <KVM guest VM IP> <KM guest VM service port> <protocol>

Stop and start the guest VM.

virsh shutdown <guest-vm-name>
virsh start <guest-vm-name>

Run the following commands to check iptables rules fo rthe guest VM

# iptables-save -t nat
# iptables-save -t filter | grep FORWARD
# iptables -t nat -L -n -v
# iptables -L FORWARD -nv --line-number

akilada/terraform-guest-vm-centos