Tested with centos 7 image.

.gitignore

@@ -11,6 +11,8 @@
 
 # Crash log files
 crash.log
+# Added to original pulled from github/gitignore
+crash*.log
 
 # Exclude all .tfvars files, which are likely to contain sentitive data, such as
 # password, private keys, and other secrets. These should not be part of version

example.tfvars

@@ -0,0 +1,19 @@
+disk-image-dir = "/path/to/disk/pool/"
+libvirt-connection-url = "qemu+ssh://<user>@<host>/system"
+
+master-nodes = 1
+worker-nodes = 2
+
+node-memory = 2048
+node-vcpus = 2
+
+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
+# base-image = "https://cloud.centos.org/centos/7/images/CentOS-7-x86_64-GenericCloud-2009.qcow2"
+
+# Password hash created with:
+# python3 -c 'import crypt; print(crypt.crypt("linux", crypt.mksalt(crypt.METHOD_SHA512)))'
+# where "linux" is the password.
+root-admin-passwd = "$6$fiLRWvGQkdK.MnZA$Co9NkA5ruuBUA389JzmKJiC8gKRohmyM09AFnVBOD7ErZnxK4RHMUlKvYg1HSgwaCXTl7H/q1svoeQeUfgc6f0"
+
+root-admin-pub-key = "ssh-rsa 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 admin"

main.tf

@@ -19,7 +19,7 @@ module "master-nodes" {
   num-nodes = var.master-nodes
   node-memory = var.node-memory
   node-vcpus = var.node-vcpus
-  base-image = var.ubuntu-image
+  base-image = var.base-image
   root-admin-passwd = var.root-admin-passwd
   root-admin-pub-key = var.root-admin-pub-key
   libvirt-connection-url = var.libvirt-connection-url
@@ -32,7 +32,7 @@ module "worker-nodes" {
   num-nodes = var.worker-nodes
   node-memory = var.node-memory
   node-vcpus = var.node-vcpus
-  base-image = var.ubuntu-image
+  base-image = var.base-image
   root-admin-passwd = var.root-admin-passwd
   root-admin-pub-key = var.root-admin-pub-key
   libvirt-connection-url = var.libvirt-connection-url

variables.tf

@@ -44,7 +44,7 @@ variable "worker-nodes" {
   type        = number
 }
 
-variable "ubuntu-image" {
+variable "base-image" {
   default = "https://cloud-images.ubuntu.com/releases/focal/release/ubuntu-20.04-server-cloudimg-amd64-disk-kvm.img"
 }