Moved everything from k8s-nodes to the top-level.

cloud_init.cfg

@@ -24,9 +24,19 @@ chpasswd:
   expire: false
 
 hostname: ${hostname}
+fqdn: ${hostname}
 
-# Use this when it's determined that we need a bigger disk image.
+%{ if install-qemu-agent }
-# This must be used in conjuction with 'size' in 'libvirt_volume'
+packages:
-# growpart:
+  # This are only necessary for libvirt.
-#   mode: auto
+  - qemu-guest-agent
-#   devices: ['/']
+runcmd:
+  # TODO At some point revisit this, this was added because it seemed like
+  # apparmor was causing dhclient to not get an IP address for ubuntu. This
+  # should be double checked.
+  - echo "/proc/*/task/*/comm wr," | tee -a /etc/apparmor.d/local/sbin.dhclient
+  # These are only necessary for libvirt.
+  - systemctl enable qemu-guest-agent
+  - systemctl start qemu-guest-agent
+  - systemctl status qemu-guest-agent
+%{ endif }

example.tfvars

@@ -10,6 +10,15 @@ libvirt-connection-url = "qemu+ssh://<user>@<host>/system"
 node-memory = 2048
 node-vcpus = 2
 
+## libvirt disk size
+# 1 GiB = 1073741824
+# 4 GiB
+# libvirt-node-disk-size = "${4 * 1073741824}"
+# 8 GiB
+# libvirt-node-disk-size = "${8 * 1073741824}"
+# 12 GiB
+# libvirt-node-disk-size = "${12 * 1073741824}"
+
 ################################################################################
 # AWS EC2 instance types
 ################################################################################
@@ -51,8 +60,18 @@ base-image = "ami-0dd0ccab7e2801812"
 ################################################################################
 
 # base-image = "https://cloud-images.ubuntu.com/releases/focal/release/ubuntu-20.04-server-cloudimg-amd64-disk-kvm.img"
-# From https://cloud.centos.org/centos/7/images/ from	2020-11-12 06:52
+# From https://cloud.centos.org/centos/7/images/ from	2020-12-06
-# base-image = "https://cloud.centos.org/centos/7/images/CentOS-7-x86_64-GenericCloud-2009.qcow2"
+# base-image = "https://cloud.centos.org/centos/7/images/CentOS-7-x86_64-GenericCloud-2111.qcow2"
+
+## Arch
+# From https://gitlab.archlinux.org/archlinux/arch-boxes/-/jobs/40102/artifacts/browse/output
+# on 2021-11-28
+# base-image = "/media/nas/software/isos/Arch-Linux-x86_64-libvirt-20211128.40102.box"
+
+## Arch
+# From https://gitlab.archlinux.org/archlinux/arch-boxes/-/jobs/40102/artifacts/browse/output
+# on 2021-11-28
+# base-image = "/media/nas/software/isos/Arch-Linux-x86_64-libvirt-20211128.40102.box"
 
 ################################################################################
 # Keys/Passwords

get-libvirt-bridge-ips.sh

@@ -0,0 +1,81 @@
+#!/bin/bash
+
+# This script will grab the IPs for libvirt VMs. This script is only needed when
+# using a bridge as the network for the VMs. This should only be needed while
+# https://github.com/dmacvicar/terraform-provider-libvirt/issues/891 is
+# unresolved.
+
+# These are the network interfaces that this script will attempt to get the IP
+# address for.
+# Ubuntu 20.04    ens3
+# Centos 7 & 8    eth0
+NET_INTERFACES="eth0 ens3"
+
+LIBVIRT_CONNECTION_URL="libvirt-connection-url"
+VM_NAME_PREFIX="vm-name-prefix"
+
+INV_GROUPS="$( \
+cat terraform.tfstate | \
+    jq '.resources[] | select(.type=="libvirt_domain") | .module' | \
+    sed 's/".*\[\\"\(.*\)\\.*$/\1/g' )"
+
+# Grab the connection URL and the vm name prefix. We do this by greping all
+# *.tfvars files making sure to cat terraform.tfvars last. Then we just grab the
+# last grep result, this way we make sure any value in terraform.tfvars will
+# take priority.
+CONN_URLS="$( \
+    find . -name "*.tfvars" -exec grep "$LIBVIRT_CONNECTION_URL" {} \; && \
+    grep "$LIBVIRT_CONNECTION_URL" terraform.tfvars)"
+
+CONN_URL="$(echo "$CONN_URLS" | tail -n 1 | sed 's/^.*=\s*"\(.*\)"/\1/g')"
+
+NAME_PREFIXES="$( \
+    find . -name "*.tfvars" -exec grep "$VM_NAME_PREFIX" {} \; && \
+    grep "$VM_NAME_PREFIX" terraform.tfvars)"
+
+NAME_PREFIX="$(echo "$NAME_PREFIXES" | tail -n 1 | sed 's/^.*=\s*"\(.*\)"/\1/g')"
+
+# These can be used for debugging.
+# echo "Using connection URL: $CONN_URL"
+# echo "Using prefix: $NAME_PREFIX"
+
+# Get the names of our VMs from libvirt.
+VMS="$(virsh -c $CONN_URL list --all | grep $NAME_PREFIX | awk '{print $2}')"
+
+# Convert the lines of VM names to an array.
+OLD_IFS=$IFS
+IFS=$'\n'
+VMS=($VMS)
+IFS=$OLD_IFS
+
+# Loop over our VM array and grab the ipv4 IP address from libvirt. Then add the
+# result to VM_IP_PAIRS as <vm-name>:<ipv4-address>.
+VM_IP_PAIRS=""
+for VM in "${VMS[@]}"; do
+    for INTERFACE in $NET_INTERFACES; do
+        IP="$( \
+            virsh -c $CONN_URL qemu-agent-command $VM '{"execute": "guest-network-get-interfaces"}' | \
+            jq '.return[] | select(.name=="'"$INTERFACE"'") | ."ip-addresses"[] | select(."ip-address-type"=="ipv4") | ."ip-address"' | \
+            sed 's/"//g')"
+        # Add the VM:IP pair if IP is not empty.
+        if [ ! -z "$IP" ]; then
+            VM_IP_PAIRS="$VM_IP_PAIRS"$'\n'"$VM:$IP"
+        fi
+    done
+done
+
+# Write inventory
+cat /dev/null > inventory
+for GROUP in $INV_GROUPS; do
+    echo "[$GROUP]" >> inventory
+    echo "$VM_IP_PAIRS" | \
+        grep $GROUP | \
+        sed 's/^\(.*\):\(.*\)$/\1 ansible_host=\2/g' >> inventory
+done
+
+# Print vars
+echo "$VM_IP_PAIRS" | \
+    sed 's/^\(.*\):\(.*\)$/\1=\2/g' | \
+    sed s/$NAME_PREFIX-//g | \
+    sed 's/-/_/g' | \
+    awk '{print toupper($1)}'

get-vm-ips.sh

@@ -1,60 +1,92 @@
-#!/bin/sh
+#!/bin/bash
 
-# This script will create environment variables for all of the output IPs. It
+# This script will create environment variables for all of the output IPs. An
-# will also create a `ANSIBLE_INV` variable that will be a comma separated
+# anisble inventory file is created as well.
-# string of all the IPs. A anisble inventory file called "inventory is created
-# as well.
 #
 # Use eval $(./get-vm-ips.sh) to set env vars for ips.
 
 terraform refresh > /dev/null
 
-# All terraform outputs in json format.
+# The file to write the inventory to. This file will be completely overridden.
-OUTPUTS_JSON="$(
+INVENTORY_FILE="inventory"
-    terraform show -json | \
+
-        jq '.values.outputs' | \
+# Grab the the vm name prefix. We do this by greping all *.tfvars files making
-        sed 's/-/_/g')"
+# sure to cat terraform.tfvars last. Then we just grab the last grep result,
-# Just the IP address outputs in json format. Also all '-' characters are
+# this way we make sure any value in terraform.tfvars will take priority.
-# replaced by '_' becuase '-' causes jq some problems.
+VM_NAME_PREFIX_VAR="vm-name-prefix"
-IPS_JSON="$(
+VM_NAME_PREFIXES="$( \
-    echo $OUTPUTS_JSON | \
+    find . -name "*.tfvars" -exec grep "$VM_NAME_PREFIX_VAR" {} \; && \
-        jq 'to_entries | .[] | select(.key | contains("ips"))')"
+    grep "$VM_NAME_PREFIX_VAR" terraform.tfvars)"
-# An array of all node "types"
+VM_NAME_PREFIX="$(
-NODE_TYPE_ARRAY="$(
+    echo "$VM_NAME_PREFIXES" | \
-    echo $IPS_JSON | \
+        tail -n 1 | \
-        jq '.value.value | to_entries | .[] | .key' | \
+        sed 's/^.*=\s*"\(.*\)"/\1/g')"
+
+# This command stores the output data in the format below.
+# [
+#   {
+#     "group": "master",
+#     "vms": [
+#       {
+#         "hostname": "ansible-test-master-0",
+#         "ip": "52.14.114.48"
+#       }
+#     ]
+#   },
+#   {
+#     "group": "worker",
+#     "vms": [
+#       {
+#         "hostname": "ansible-test-worker-0",
+#         "ip": "3.145.121.159"
+#       },
+#       {
+#         "hostname": "ansible-test-worker-1",
+#         "ip": "18.217.112.176"
+#       }
+#     ]
+#   }
+# ]
+DATA="$(terraform show -json | \
+    jq '.values.outputs.groups_hostnames_ips.value | to_entries |
+        map({group: .key, vms:.value | to_entries |
+        map({hostname:.key,ip:.value})})')"
+
+# Pull out the groups from $DATA. The format is a single string with the groups
+# separated by spaces, ie. "group1 group2 group3".
+ANS_GROUPS="$(
+    echo $DATA | \
+        jq '.[] | .group' | \
         sed 's/"//g' | \
-        sed -z 's/\n/ /g;s/ $/\n/g')"
+        tr '\n' ' '
+    )"
 
-# Loop over all the node types and create an export line for each IP.
+# Clear the inventory file.
-VM_IP_EXPORTS="$(
+cat /dev/null > $INVENTORY_FILE
-    for TYPE in $NODE_TYPE_ARRAY; do
 
-        # Convert type, converts "master-ips" to "MASTER"
+# For each group, write the VM info to $INVENTORY_FILE and also print a variable
-        TYPE_UPPER="$(echo ${TYPE^^} | sed s/_.*$//g)"
+# expression to stdout.
-        echo "$IPS_JSON" | \
+for GROUP in $ANS_GROUPS; do
-            jq '.value.value.'"$TYPE"'[]' | \
-            # Add line numbers starting with 0.
-            nl -v 0 | \
-            # Print an export string with a type placeholder "__TYPE__".
-            awk '{print "export __TYPE___" $1 "=" $2}' | \
-            sed s/__TYPE__/$TYPE_UPPER/g
-    done)"
 
-ANSIBLE_INV="$(
+    # Write the inventory file to $INVENTORY_FILE.
-    echo "$VM_IP_EXPORTS" | \
+    echo "[$GROUP]" >> $INVENTORY_FILE
-        sed 's/"//g' | \
+    echo $DATA | \
-        sed 's/^.*=//g' | \
+        jq '.[] | select(.group=="'"$GROUP"'") | .vms[] | 
-        sed -z 's/\n/,/g;s/,$/\n/g')"
+            "\(.hostname) ansible_host=\(.ip)"' | \
+        sed 's/"//g' \
+            >> $INVENTORY_FILE
 
-# Create an inventory file for ansible.
+    # For this group, collect expressions into VARS. The format is:
-echo "[k8s_nodes]" > inventory
+    # HOSTNAME1=0.0.0.0
-echo $VM_IP_EXPORTS | \
+    # HOSTNAME2=0.0.0.0
-    sed 's/"//g' | \
+    VARS="$(
-    sed 's/export //g' | \
+        echo $DATA | \
-    sed 's/ /\n/g' | \
+            jq '.[] | select(.group=="'"$GROUP"'") | .vms[] | 
-    sed 's/^\(.*\)\(=.*\)$/\1 ansible_host\2/g' \
+                "\(.hostname)=\(.ip)"' | \
-        >> inventory
+            sed 's/"//g' | \
-
+            sed "s/$VM_NAME_PREFIX-//g" | \
-echo $VM_IP_EXPORTS | sed 's/" /"\n/g'
+            sed 's/-/_/g'
-echo export ANSIBLE_INV=$ANSIBLE_INV
+        )"
+    # Print the contents of $VARS converted to uppercase.
+    echo "${VARS^^}"
+done

main.tf

@@ -1,24 +1,16 @@
-terraform {
-  required_version = ">= 1.0.8"
-  required_providers {
-    libvirt = {
-      source  = "dmacvicar/libvirt"
-      version = "0.6.11"
-    }
-  }
-}
 
 locals {
   nodes-config = {
     "master" = {
-      base-image = var.amzn2-ami
+      base-image = var.centos8-ami
       num = 1
     },
     "worker" = {
-      base-image = var.amzn2-ami
+      base-image = var.centos8-ami
       num = 2
     }
   }
+  install-qemu-agent = false
 }
 
 ################################################################################
@@ -33,6 +25,7 @@ module "cloud-init-config" {
   num                 = each.value.num
   root-admin-passwd   = var.root-admin-passwd
   root-admin-pub-key  = var.root-admin-pub-key
+  install-qemu-agent  = local.install-qemu-agent
 }
 
 ################################################################################
@@ -41,10 +34,6 @@ module "cloud-init-config" {
 # libvirt modules/resources.
 ################################################################################
 
-provider "aws" {
-  region = "us-east-2"
-}
-
 # This module will grab the latest ami for a variety of distros. Uncomment to
 # get a list of the latest AMIs for our supported distros.
 # module "aws-amis" {
@@ -54,14 +43,27 @@ provider "aws" {
 #   value = module.aws-amis.amis
 # }
 
-module "aws-network" {
+################################################################################
-  source            = "./modules/aws-network"
+# AWS Networking
-  name-prefix       = var.vm-name-prefix
+# Use of the 2 modules below to create resources for the AWS network.
-  vpc-cidr-block    = var.aws-vpc-cidr-block
+# aws-network-from-scratch will build the AWS network from scratch.
-  subnet-cidr-block = var.aws-subnet-cidr-block
+# aws-network-existing will query AWS for an existing VPC.
-  admin-ips         = var.admin-ips
+################################################################################
+
+# module "aws-network-from-scratch" {
+#   source            = "./modules/aws-network-from-scratch"
+#   name-prefix       = var.vm-name-prefix
+#   vpc-cidr-block    = var.aws-vpc-cidr-block
+#   subnet-cidr-block = var.aws-subnet-cidr-block
+#   admin-ips         = var.admin-ips
+# }
+
+module "aws-network-existing" {
+  source = "./modules/aws-network-existing"
 }
 
+################################################################################
+
 # This key pair is not actually used. Keys are added to the nodes via cloud-init
 # instead. We just add this here that this key will show up in the AWS console."
 resource "aws_key_pair" "key" {
@@ -106,7 +108,9 @@ module "nodes" {
 #   num-nodes              = each.value.num
 #   node-memory            = var.node-memory
 #   node-vcpus             = var.node-vcpus
+#   node-disk-size         = var.libvirt-node-disk-size
 #   base-image             = each.value.base-image
+#   network-name           = var.libvirt-network-name
 #   root-admin-passwd      = var.root-admin-passwd
 #   root-admin-pub-key     = var.root-admin-pub-key
 #   libvirt-connection-url = var.libvirt-connection-url
@@ -123,6 +127,8 @@ module "nodes" {
 # end libvirt
 ################################################################################
 
-output "ips" {
+# This will output a map of group => [{hostname, ip}].
-  value = { for type, node in module.nodes : type => node.ips }
+# TODO A 'names' output needs to be added to libvirt.
+output "groups_hostnames_ips" {
+  value = { for type, node in module.nodes : type => zipmap(node.names, node.ips) }
 }

modules/aws-network-existing/main.tf

@@ -0,0 +1,23 @@
+locals {
+  az-to-subnets = {
+    for s in data.aws_subnet.subnets : s.availability_zone => s.id...
+  }
+}
+
+data "aws_vpc" "default" {
+  tags = {
+    Name = var.default-vpc-name
+  }
+}
+
+data "aws_subnets" "subnet-ids" {
+  filter {
+    name = "vpc-id"
+    values = [data.aws_vpc.default.id]
+  }
+}
+
+data "aws_subnet" "subnets" {
+  for_each = toset(data.aws_subnets.subnet-ids.ids)
+  id = each.key
+}

modules/aws-network-existing/outputs.tf

@@ -0,0 +1,18 @@
+output "default-vpc" {
+  value = data.aws_vpc.default
+}
+
+output "subnets" {
+  description = "An array of all subnets in default-vpc."
+  value = data.aws_subnet.subnets
+}
+
+output "k8s-subnets" {
+  description = "An array of subnets to be used for k8s VMs. These subnets were chosen by selecting a single subnet from each availability_zone."
+  value = [for k,v in local.az-to-subnets : v[0]]
+}
+
+output "az-to-subnets" {
+  description = "A map of availability zone to array of subnets that are in thet availability zone."
+  value = local.az-to-subnets
+}

modules/aws-network-existing/variables.tf

@@ -0,0 +1,4 @@
+variable "default-vpc-name" {
+  description = "The name of the existing default VPC. This module will query AWS for a VPC with this name,"
+  default = "Managed VPC"
+}

modules/aws-network-from-scratch/main.tf

@@ -33,7 +33,7 @@ resource "aws_default_security_group" "sg" {
   }
 
   tags = {
-    Name = "${var.name-prefix}-ssh-from-admins--sg"
+    Name = "${var.name-prefix}-ssh-from-admins-sg"
   }
 }
 

modules/aws-nodes/main.tf

@@ -1,6 +1,7 @@
 resource "aws_instance" "nodes" {
   ami                         = var.ami
   instance_type               = var.ec2-instance-type
+  # TODO REM double check this key.
   # key_name                    = aws_key_pair.debug1.key_name
   associate_public_ip_address = true
   subnet_id                   = var.subnet-id

modules/aws-nodes/outputs.tf

@@ -1,3 +1,7 @@
 output "ips" {
   value = aws_instance.nodes.*.public_ip
 }
+
+output "names" {
+  value = aws_instance.nodes.*.tags.Name
+}

modules/cloud-init-config/main.tf

@@ -1,9 +1,10 @@
 data "template_file" "user-datas" {
   template = file("${var.cloud-init-template}")
   vars = {
-    admin-passwd  = "${var.root-admin-passwd}"
+    admin-passwd       = "${var.root-admin-passwd}"
-    admin-pub-key = "${var.root-admin-pub-key}"
+    admin-pub-key      = "${var.root-admin-pub-key}"
-    hostname      = "${var.hostname-prefix}-${count.index}"
+    hostname           = "${var.hostname-prefix}-${count.index}"
+    install-qemu-agent = var.install-qemu-agent
   }
   count = var.num
 }

modules/cloud-init-config/variables.tf

@@ -8,6 +8,12 @@ variable "hostname-prefix" {
   description = "This prefix wil be applied as a prefix for the hostnames."
 }
 
+variable "install-qemu-agent" {
+  default     = false
+  description = "This flag determines whether or not qemu-agent is installed."
+  type        = bool
+}
+
 variable "num" {
   description = "The number of user-datas to create with these parameters."
 }

modules/libvirt-nodes/main.tf

@@ -9,13 +9,20 @@ terraform {
 }
 
 resource "libvirt_volume" "node-images" {
-  name   = "${var.name-prefix}-${count.index}"
+  name   = "${var.name-prefix}-base"
   pool   = var.pool-name
   source = var.base-image
-  count  = var.num-nodes
   format = "qcow2"
 }
 
+resource "libvirt_volume" "node-images-resized" {
+  name           = "${var.name-prefix}-${count.index}-resized"
+  pool           = var.pool-name
+  base_volume_id = libvirt_volume.node-images.id
+  count          = var.num-nodes
+  size           = var.node-disk-size
+}
+
 data "template_file" "network-config" {
   template = file("${path.module}/network_config.cfg")
 }
@@ -37,9 +44,9 @@ resource "libvirt_domain" "nodes" {
   cloudinit = element(libvirt_cloudinit_disk.node-inits.*.id, count.index)
 
   network_interface {
-    network_name   = "default"
+    network_name   = var.network-name
     hostname       = "${var.name-prefix}-${count.index}"
-    wait_for_lease = true
+    # wait_for_lease = true
   }
 
   # IMPORTANT: this is a known bug on cloud images, since they expect a console
@@ -58,7 +65,7 @@ resource "libvirt_domain" "nodes" {
   }
 
   disk {
-    volume_id = element(libvirt_volume.node-images.*.id, count.index)
+    volume_id = element(libvirt_volume.node-images-resized.*.id, count.index)
   }
 
   graphics {

modules/libvirt-nodes/outpus.tf

@@ -1,4 +1,6 @@
 
-output "ips" {
+# This only works on the default network. They will not work using the bridged
-  value = libvirt_domain.nodes.*.network_interface.0.addresses.0
+# network.
-}
+# output "ips" {
+#   value = libvirt_domain.nodes.*.network_interface.0.addresses.0
+# }

modules/libvirt-nodes/variables.tf

@@ -12,6 +12,16 @@ variable "name-prefix" {
   description = "This will be a prefix for all resource names, ie. domains will be created suck as \"k8s-node-2\"."
 }
 
+variable "network-name" {
+  default = "default"
+  description = "The name of a pre-existing virtual-network."
+}
+
+variable "node-disk-size" {
+  default = 4294967296
+  description = "The size of the disk to be used for libvirt nodes. (in bytes)"
+}
+
 variable "node-memory" {
   default     = "2048"
   description = "The amount of memory to be used for all the nodes."

providers.tf

@@ -0,0 +1,76 @@
+
+provider "aws" {
+  region = "us-gov-west-1"
+}
+
+
+terraform {
+  required_version = ">= 1.0.8"
+
+    backend "s3" {
+      
+      bucket            = "mss-terraform-state"
+      key               = "global/s3/terraform.tfstate"
+      region            = "us-gov-west-1"
+      
+      dynamodb_table    = "mss-terraform-state-lock"
+      encrypt           = true
+
+  }
+  required_providers {
+    libvirt = {
+      source  = "dmacvicar/libvirt"
+      version = "0.6.11"
+    }
+  }
+}
+
+
+
+
+
+##
+#S3 bucket create to hold our TFState file so we can all share env settings
+resource "aws_s3_bucket" "terraform_state" {
+    bucket = "mss-terraform-state"
+
+    # enable versioning for the state files 
+    versioning {
+        enabled = true
+    }
+
+    #enable server-side encryption
+    server_side_encryption_configuration {
+      
+      rule {
+          apply_server_side_encryption_by_default {
+              sse_algorithm = "AES256"
+              }
+          }
+        } 
+}
+
+##
+# no sql database used so that we can lock the TFstate file in the S3 bucket to ensure two people 
+# are not running a terraform command at the same time 
+resource "aws_dynamodb_table" "terraform_locks" {
+    name            = "mss-terraform-state-lock"
+    billing_mode    = "PAY_PER_REQUEST"
+    hash_key        = "LockID"
+
+    attribute {
+      name = "LockID"
+      type = "S"
+    }
+
+
+}
+
+
+##
+# output variable to give details on the s3 bucket created
+#TODO: move to output.tf
+output "s3_bucket_arn" {
+  value       = aws_s3_bucket.terraform_state.arn
+  description = "The ARN of the S3 bucket"
+}

variables.tf

@@ -8,6 +8,11 @@ variable "aws-ec2-instance-type" {
   description = "The AWS instance type to use for all nodes."
 }
 
+variable "aws-region" {
+  default = "us-east-1"
+  description = "The AWS region to use."
+}
+
 variable "aws-subnet-cidr-block" {
   default = "10.0.1.0/24"
   description = "The address space to be used for this subnet."
@@ -31,6 +36,16 @@ variable "libvirt-connection-url" {
   description = "The libvirt connection URI, ie. qemu+ssh://<user>@<host>/system"
 }
 
+variable "libvirt-network-name" {
+  default = "default"
+  description = "The name of a pre-existing libvirt virtual-network."
+}
+
+variable "libvirt-node-disk-size" {
+  default = 4294967296
+  description = "The size of the disk to be used for libvirt nodes. (in bytes)"
+}
+
 variable "node-memory" {
   default     = "2048"
   description = "The amount of memory to be used for all the nodes."
@@ -107,3 +122,25 @@ variable "rhel8-ami" {
   default = "ami-0d871ca8a77af2948"
   description = "The AMI to use for RHEL 8."
 }
+
+################################################################################
+# Libvirt Images
+# These variables are really mor like constants. Using variables improves
+# readability. The defaults are manually updated.
+################################################################################
+
+variable "ubuntu-img" {
+  default     = "https://cloud-images.ubuntu.com/releases/focal/release/ubuntu-20.04-server-cloudimg-amd64-disk-kvm.img"
+  description = "The libvirt image tp use for Ubuntu."
+}
+
+variable "centos7-img" {
+  # Latest as of 2021-12-06.
+  default = "https://cloud.centos.org/centos/7/images/CentOS-7-x86_64-GenericCloud-2111.qcow2"
+  description = "The libvirt image tp use for CentOS 7."
+}
+
+variable "centos8-img" {
+  default = "https://cloud.centos.org/centos/8/x86_64/images/CentOS-8-GenericCloud-8.4.2105-20210603.0.x86_64.qcow2"
+  description = "The libvirt image tp use for CentOS 8."
+}