From 8724cede199140571a74cf9c8ea6aa8c98ed480a Mon Sep 17 00:00:00 2001
From: shnee <shnee@shnee.net>
Date: Tue, 16 Nov 2021 14:38:06 -0500
Subject: [PATCH 1/6] Create ansible invetory with get-vm-ips.sh

---
 .gitignore     |  1 +
 example.tfvars | 27 ++++++++++++++++++++++
 get-vm-ips.sh  | 63 +++++++++++++++++++++++++++++++++++++++++---------
 3 files changed, 80 insertions(+), 11 deletions(-)

diff --git a/.gitignore b/.gitignore
index b47f542..7103111 100644
--- a/.gitignore
+++ b/.gitignore
@@ -45,4 +45,5 @@ terraform.rc
 
 k8s-key*
 STARTHERE
+inventory
 
diff --git a/example.tfvars b/example.tfvars
index 33a78d3..4b6100d 100644
--- a/example.tfvars
+++ b/example.tfvars
@@ -1,3 +1,5 @@
+vm-name-prefix = "docker-ansible-test"
+
 # A CIDR block ending in '/32' equates to a single IP address, '0.0.0.0/0'
 # equates to any ip address.
 admin-ips = [ "8.8.8.8/32", "0.0.0.0/0" ]
@@ -18,10 +20,35 @@ aws-ec2-instance-type = "t2.micro"
 # 4 GiB, 2 vcpus
 # aws-ec2-instnce-type = "t2.medium"
 
+################################################################################
+# AWS images (AMIs)
+################################################################################
+
+## Amazon Linux 2
 # AWS Amazon Linux 2 AMI (HVM), SSD Volume Type - Oregon - 2021.11.11 - free
 # base-image = "ami-00be885d550dcee43"
 # AWS Amazon Linux 2 AMI (HVM), SSD Volume Type - us-east-2 - 2021.11.12 - free
 base-image = "ami-0dd0ccab7e2801812"
+
+## CentOS
+# CentOS 7.9.2009 x86_64 - us-east-2 - 2021-11-15
+# base-image = "ami-00f8e2c955f7ffa9b"
+# CentOS 8.4.2105 x86_64 - us-east-2 - 2021-11015
+# base-image = "ami-057cacbfbbb471bb3"
+
+## Ubuntu
+# Ubuntu Server 20.04 LTS (HVM), SSD Volume Type
+# us-east-2 - (64-bit x86) - 2021.11.12 - free
+# base-image = "ami-0629230e074c580f2"
+
+## Arch linux
+# arch-linux-lts-hvm-2021.06.02.x86_64-ebs - us-east-2
+# base-image = "ami-02653f06de985e3ba"
+
+################################################################################
+# libvirt images
+################################################################################
+
 # 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"
diff --git a/get-vm-ips.sh b/get-vm-ips.sh
index 25e36fe..8eceb68 100755
--- a/get-vm-ips.sh
+++ b/get-vm-ips.sh
@@ -1,19 +1,60 @@
 #!/bin/sh
 
+# This script will create environment variables for all of the output IPs. It
+# will also create a `ANSIBLE_INV` variable that will be a comma separated
+# 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
 
-IPS_JSON="$(terraform show -json | jq '.values.outputs')"
+# All terraform outputs in json format.
+OUTPUTS_JSON="$(
+    terraform show -json | \
+        jq '.values.outputs' | \
+        sed 's/-/_/g')"
+# Just the IP address outputs in json format. Also all '-' characters are
+# replaced by '_' becuase '-' causes jq some problems.
+IPS_JSON="$(
+    echo $OUTPUTS_JSON | \
+        jq 'to_entries | .[] | select(.key | contains("ips"))')"
+# An array of all node "types"
+NODE_TYPE_ARRAY="$(
+    echo $IPS_JSON | \
+        jq '.key' | \
+        sed 's/"//g' | \
+        sed -z 's/\n/ /g;s/ $/\n/g')"
 
-echo $IPS_JSON | \
-    jq '."master-ips".value[]' | \
-    nl -v 0 | \
-    awk '{print "export MASTER" $1 "=" $2}' | \
-    sed 's/"//g'
+# Loop over all the node types and create an export line for each IP.
+VM_IP_EXPORTS="$(
+    for TYPE in $NODE_TYPE_ARRAY; do
 
-echo $IPS_JSON | \
-    jq '."worker-ips".value[]' | \
-    nl -v 0 | \
-    awk '{print "export WORKER" $1 "=" $2}' | \
-    sed 's/"//g'
+        # Convert type, converts "master-ips" to "MASTER"
+        TYPE_UPPER="$(echo ${TYPE^^} | sed s/_.*$//g)"
+        echo "$OUTPUTS_JSON" | \
+            jq '.'"$TYPE"'.value[]' | \
+            # 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="$(
+    echo "$VM_IP_EXPORTS" | \
+        sed 's/"//g' | \
+        sed 's/^.*=//g' | \
+        sed -z 's/\n/,/g;s/,$/\n/g')"
+
+# Create an inventory file for ansible.
+echo "[k8s_nodes]" > inventory
+echo $VM_IP_EXPORTS | \
+    sed 's/"//g' | \
+    sed 's/export //g' | \
+    sed 's/ /\n/g' | \
+    sed 's/^\(.*\)\(=.*\)$/\1 ansible_host\2/g' \
+        >> inventory
+
+echo $VM_IP_EXPORTS | sed 's/" /"\n/g'
+echo export ANSIBLE_INV=$ANSIBLE_INV

From 3088e2295f7a4aeedb4d5713e6edef25f60926c1 Mon Sep 17 00:00:00 2001
From: shnee <shnee@shnee.net>
Date: Wed, 17 Nov 2021 14:18:31 -0500
Subject: [PATCH 2/6] Added a aws_ami module.

---
 main.tf                     |  8 +++++
 modules/aws-amis/main.tf    | 58 +++++++++++++++++++++++++++++++++++++
 modules/aws-amis/outputs.tf |  3 ++
 3 files changed, 69 insertions(+)
 create mode 100644 modules/aws-amis/main.tf
 create mode 100644 modules/aws-amis/outputs.tf

diff --git a/main.tf b/main.tf
index 20f8bfc..69c7943 100644
--- a/main.tf
+++ b/main.tf
@@ -42,6 +42,10 @@ provider "aws" {
   region = "us-east-2"
 }
 
+module "aws-amis" {
+  source = "./modules/aws-amis"
+}
+
 module "aws-network" {
   source = "./modules/aws-network"
   name-prefix = var.vm-name-prefix
@@ -82,6 +86,10 @@ module "worker-nodes" {
   name-prefix        = "${var.vm-name-prefix}-worker"
 }
 
+output "amis" {
+  value = module.aws-amis.amis
+}
+
 ################################################################################
 # end aws
 ################################################################################
diff --git a/modules/aws-amis/main.tf b/modules/aws-amis/main.tf
new file mode 100644
index 0000000..1949653
--- /dev/null
+++ b/modules/aws-amis/main.tf
@@ -0,0 +1,58 @@
+locals {
+  amis = {
+    amzn2 = {
+      owner-id = "137112412989"
+      name = "amzn2-ami-hvm-2*x86_64-gp2"
+    },
+    ubuntu = {
+      owner-id = "099720109477"
+      name = "ubuntu/images/hvm-ssd/ubuntu-focal-20.04-amd64-server-*"
+    },
+    centos7 = {
+      owner-id = "125523088429"
+      name = "CentOS 7.*x86_64"
+    },
+    centos8 = {
+      owner-id = "125523088429"
+      name = "CentOS 8.*x86_64"
+    },
+    arch = {
+      owner-id = "093273469852"
+      name = "arch-linux-lts-hvm*x86_64-ebs"
+    },
+    rhel7 = {
+      owner-id = "309956199498"
+      name = "RHEL-7.*HVM*x86_64*GP2"
+    },
+    rhel8 = {
+      owner-id = "309956199498"
+      name = "RHEL-8.*HVM*x86_64*GP2"
+    }
+  }
+}
+
+data "aws_ami" "amis" {
+  for_each = local.amis
+  most_recent = true
+  owners = [each.value.owner-id]
+
+  filter {
+    name = "name"
+    values = [each.value.name]
+  }
+
+  filter {
+    name = "virtualization-type"
+    values = ["hvm"]
+  }
+
+  filter {
+    name = "architecture"
+    values = ["x86_64"]
+  }
+
+  filter {
+    name = "root-device-type"
+    values = ["ebs"]
+  }
+}
diff --git a/modules/aws-amis/outputs.tf b/modules/aws-amis/outputs.tf
new file mode 100644
index 0000000..3174fd9
--- /dev/null
+++ b/modules/aws-amis/outputs.tf
@@ -0,0 +1,3 @@
+output "amis" {
+  value = tomap({ for type, ami in data.aws_ami.amis : type => ami.id })
+}

From 9aa0a68be81dab001a916ace5fb69bf4a4a3dae1 Mon Sep 17 00:00:00 2001
From: shnee <shnee@shnee.net>
Date: Wed, 17 Nov 2021 21:50:07 -0500
Subject: [PATCH 3/6] AWS nodes and user-data created from config map.

---
 example.tfvars                         | 23 ++++++-
 main.tf                                | 83 +++++++++-----------------
 modules/cloud-init-config/main.tf      |  9 +++
 modules/cloud-init-config/outputs.tf   |  3 +
 modules/cloud-init-config/variables.tf | 22 +++++++
 variables.tf                           |  5 ++
 6 files changed, 90 insertions(+), 55 deletions(-)
 create mode 100644 modules/cloud-init-config/main.tf
 create mode 100644 modules/cloud-init-config/outputs.tf
 create mode 100644 modules/cloud-init-config/variables.tf

diff --git a/example.tfvars b/example.tfvars
index 4b6100d..4ea7b3c 100644
--- a/example.tfvars
+++ b/example.tfvars
@@ -1,4 +1,4 @@
-vm-name-prefix = "docker-ansible-test"
+vm-name-prefix = "k8s-tf"
 
 # A CIDR block ending in '/32' equates to a single IP address, '0.0.0.0/0'
 # equates to any ip address.
@@ -13,6 +13,10 @@ worker-nodes = 2
 node-memory = 2048
 node-vcpus = 2
 
+################################################################################
+# AWS EC2 instance types
+################################################################################
+
 # 1 GiB, 1 vcpu, only one that is free.
 # This one won't work with k8s because it requires at least 2 vcpus.
 aws-ec2-instance-type = "t2.micro"
@@ -20,6 +24,19 @@ aws-ec2-instance-type = "t2.micro"
 # 4 GiB, 2 vcpus
 # aws-ec2-instnce-type = "t2.medium"
 
+################################################################################
+
+nodes-config = {
+  "master" = {
+    base-image = "ami-0dd0ccab7e2801812"
+    num = 1
+  },
+  "worker" = {
+    base-image = "ami-0dd0ccab7e2801812"
+    num = 2
+  }
+}
+
 ################################################################################
 # AWS images (AMIs)
 ################################################################################
@@ -53,6 +70,10 @@ base-image = "ami-0dd0ccab7e2801812"
 # 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"
 
+################################################################################
+# Keys/Passwords
+################################################################################
+
 # Password hash created with:
 # python3 -c 'import crypt; print(crypt.crypt("linux", crypt.mksalt(crypt.METHOD_SHA512)))'
 # where "linux" is the password.
diff --git a/main.tf b/main.tf
index 69c7943..ce42da9 100644
--- a/main.tf
+++ b/main.tf
@@ -1,8 +1,8 @@
 terraform {
-  required_version = ">= 0.13"
+  required_version = ">= 1.0.8"
   required_providers {
     libvirt = {
-      source = "dmacvicar/libvirt"
+      source  = "dmacvicar/libvirt"
       version = "0.6.11"
     }
   }
@@ -12,24 +12,14 @@ terraform {
 # cloud-init
 ################################################################################
 
-data "template_file" "master-node-user-datas" {
-  template = file("${path.module}/cloud_init.cfg")
-  vars = {
-    admin-passwd  = "${var.root-admin-passwd}"
-    admin-pub-key = "${var.root-admin-pub-key}"
-    hostname      = "${var.vm-name-prefix}-master-${count.index}"
-  }
-  count = var.master-nodes
-}
-
-data "template_file" "worker-node-user-datas" {
-  template = file("${path.module}/cloud_init.cfg")
-  vars = {
-    admin-passwd  = "${var.root-admin-passwd}"
-    admin-pub-key = "${var.root-admin-pub-key}"
-    hostname      = "${var.vm-name-prefix}-worker-${count.index}"
-  }
-  count = var.worker-nodes
+module "cloud-init-config" {
+  for_each            = var.nodes-config
+  source              = "./modules/cloud-init-config"
+  cloud-init-template = "${path.module}/cloud_init.cfg"
+  hostname-prefix     = "${var.vm-name-prefix}-${each.key}"
+  num                 = each.value.num
+  root-admin-passwd   = var.root-admin-passwd
+  root-admin-pub-key  = var.root-admin-pub-key
 }
 
 ################################################################################
@@ -42,16 +32,20 @@ provider "aws" {
   region = "us-east-2"
 }
 
-module "aws-amis" {
-  source = "./modules/aws-amis"
-}
+# This module will grab the latest ami for a variety of distros.
+# module "aws-amis" {
+#   source = "./modules/aws-amis"
+# }
+# output "amis" {
+#   value = module.aws-amis.amis
+# }
 
 module "aws-network" {
-  source = "./modules/aws-network"
-  name-prefix = var.vm-name-prefix
-  vpc-cidr-block = var.aws-vpc-cidr-block
+  source            = "./modules/aws-network"
+  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
+  admin-ips         = var.admin-ips
 }
 
 # This key pair is not actually used. Keys are added to the nodes via cloud-init
@@ -64,30 +58,16 @@ resource "aws_key_pair" "key" {
   }
 }
 
-module "master-nodes" {
+module "nodes" {
+  for_each           = var.nodes-config
   source             = "./modules/aws-nodes"
-  ami                = var.base-image
+  ami                = each.value.base-image
   ec2-instance-type  = var.aws-ec2-instance-type
   subnet-id          = module.aws-network.subnet.id
   security-group-ids = [module.aws-network.default-security-group.id]
-  user-datas         = data.template_file.master-node-user-datas
-  num-nodes          = var.master-nodes
-  name-prefix        = "${var.vm-name-prefix}-master"
-}
-
-module "worker-nodes" {
-  source             = "./modules/aws-nodes"
-  ami                = var.base-image
-  ec2-instance-type  = var.aws-ec2-instance-type
-  subnet-id          = module.aws-network.subnet.id
-  security-group-ids = [module.aws-network.default-security-group.id]
-  user-datas         = data.template_file.worker-node-user-datas
-  num-nodes          = var.worker-nodes
-  name-prefix        = "${var.vm-name-prefix}-worker"
-}
-
-output "amis" {
-  value = module.aws-amis.amis
+  user-datas         = lookup(module.cloud-init-config, each.key, null).user-datas
+  num-nodes          = each.value.num
+  name-prefix        = "${var.vm-name-prefix}-${each.key}"
 }
 
 ################################################################################
@@ -142,11 +122,6 @@ output "amis" {
 # end libvirt
 ################################################################################
 
-# TODO REM move to other file?
-output "master-ips" {
-  value = module.master-nodes.ips
-}
-
-output "worker-ips" {
-  value = module.worker-nodes.ips
+output "ips" {
+  value = { for type, node in module.nodes : type => node.ips }
 }
diff --git a/modules/cloud-init-config/main.tf b/modules/cloud-init-config/main.tf
new file mode 100644
index 0000000..e1c75c4
--- /dev/null
+++ b/modules/cloud-init-config/main.tf
@@ -0,0 +1,9 @@
+data "template_file" "user-datas" {
+  template = file("${var.cloud-init-template}")
+  vars = {
+    admin-passwd  = "${var.root-admin-passwd}"
+    admin-pub-key = "${var.root-admin-pub-key}"
+    hostname      = "${var.hostname-prefix}-${count.index}"
+  }
+  count = var.num
+}
diff --git a/modules/cloud-init-config/outputs.tf b/modules/cloud-init-config/outputs.tf
new file mode 100644
index 0000000..15415d4
--- /dev/null
+++ b/modules/cloud-init-config/outputs.tf
@@ -0,0 +1,3 @@
+output "user-datas" {
+  value = data.template_file.user-datas
+}
diff --git a/modules/cloud-init-config/variables.tf b/modules/cloud-init-config/variables.tf
new file mode 100644
index 0000000..fc4f437
--- /dev/null
+++ b/modules/cloud-init-config/variables.tf
@@ -0,0 +1,22 @@
+variable "cloud-init-template" {
+  default     = "../../cloud_init.cfg"
+  description = "The path to the cloud-init config template."
+  type        = string
+}
+
+variable "hostname-prefix" {
+  description = "This prefix wil be applied as a prefix for the hostnames."
+}
+
+variable "num" {
+  description = "The number of user-datas to create with these parameters."
+}
+
+variable "root-admin-passwd" {
+  description = "This value will be substituted for any occurence of 'admin-password' in the cloud-init config template."
+}
+
+variable "root-admin-pub-key" {
+  description = "This value will be substituted for any occurence of 'admin-pub-key' in the cloud-init config template."
+}
+
diff --git a/variables.tf b/variables.tf
index 52cf7a2..e8f3211 100644
--- a/variables.tf
+++ b/variables.tf
@@ -43,6 +43,11 @@ variable "node-vcpus" {
   type        = number
 }
 
+variable "nodes-config" {
+  description = "A config that declares how many nodes of each type you want created."
+  type = map(object({base-image=string,num=number}))
+}
+
 variable "root-admin-passwd" {
   description = "This will be the password for the root and admin user. The format of this can by any format accepted by cloud-init's chpasswd module."
 }

From c9ea3d448971856c152af05f7857e8646bdbbae1 Mon Sep 17 00:00:00 2001
From: shnee <shnee@shnee.net>
Date: Thu, 18 Nov 2021 09:45:16 -0500
Subject: [PATCH 4/6] Make libvirt module accept config map.

---
 example.tfvars                |  3 ---
 main.tf                       | 25 ++++++-------------------
 modules/libvirt-nodes/main.tf |  4 ----
 3 files changed, 6 insertions(+), 26 deletions(-)

diff --git a/example.tfvars b/example.tfvars
index 4ea7b3c..df3f604 100644
--- a/example.tfvars
+++ b/example.tfvars
@@ -7,9 +7,6 @@ admin-ips = [ "8.8.8.8/32", "0.0.0.0/0" ]
 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
 
diff --git a/main.tf b/main.tf
index ce42da9..7510f3e 100644
--- a/main.tf
+++ b/main.tf
@@ -84,32 +84,19 @@ module "nodes" {
 #   uri = var.libvirt-connection-url
 # }
 # 
-# module "master-nodes" {
+# module "nodes" {
+#   for_each               = var.nodes-config
 #   source                 = "./modules/libvirt-nodes"
 #   pool-name              = libvirt_pool.images.name
-#   name-prefix            = "${var.vm-name-prefix}-master"
-#   num-nodes              = var.master-nodes
+#   name-prefix            = "${var.vm-name-prefix}-${each.key}"
+#   num-nodes              = each.value.num
 #   node-memory            = var.node-memory
 #   node-vcpus             = var.node-vcpus
-#   base-image             = var.base-image
+#   base-image             = each.value.base-image
 #   root-admin-passwd      = var.root-admin-passwd
 #   root-admin-pub-key     = var.root-admin-pub-key
 #   libvirt-connection-url = var.libvirt-connection-url
-#   user-datas             = data.template_file.master-node-user-datas
-# }
-# 
-# module "worker-nodes" {
-#   source                 = "./modules/libvirt-nodes"
-#   pool-name              = libvirt_pool.images.name
-#   name-prefix            = "${var.vm-name-prefix}-worker"
-#   num-nodes              = var.worker-nodes
-#   node-memory            = var.node-memory
-#   node-vcpus             = var.node-vcpus
-#   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
-#   user-datas             = data.template_file.worker-node-user-datas
+#   user-datas             = lookup(module.cloud-init-config, each.key, null).user-datas
 # }
 # 
 # resource "libvirt_pool" "images" {
diff --git a/modules/libvirt-nodes/main.tf b/modules/libvirt-nodes/main.tf
index 9b792d0..cbd0dac 100644
--- a/modules/libvirt-nodes/main.tf
+++ b/modules/libvirt-nodes/main.tf
@@ -8,10 +8,6 @@ terraform {
   }
 }
 
-provider "libvirt" {
-  uri = var.libvirt-connection-url
-}
-
 resource "libvirt_volume" "node-images" {
   name   = "${var.name-prefix}-${count.index}"
   pool   = var.pool-name

From 852d8cfcf2f6838af7bbadc56ddaaf01b6413203 Mon Sep 17 00:00:00 2001
From: shnee <shnee@shnee.net>
Date: Thu, 18 Nov 2021 10:45:58 -0500
Subject: [PATCH 5/6] Update get-vm-ips.sh to work with new map config.

---
 get-vm-ips.sh | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/get-vm-ips.sh b/get-vm-ips.sh
index 8eceb68..230b5cf 100755
--- a/get-vm-ips.sh
+++ b/get-vm-ips.sh
@@ -22,7 +22,7 @@ IPS_JSON="$(
 # An array of all node "types"
 NODE_TYPE_ARRAY="$(
     echo $IPS_JSON | \
-        jq '.key' | \
+        jq '.value.value | to_entries | .[] | .key' | \
         sed 's/"//g' | \
         sed -z 's/\n/ /g;s/ $/\n/g')"
 
@@ -32,12 +32,12 @@ VM_IP_EXPORTS="$(
 
         # Convert type, converts "master-ips" to "MASTER"
         TYPE_UPPER="$(echo ${TYPE^^} | sed s/_.*$//g)"
-        echo "$OUTPUTS_JSON" | \
-            jq '.'"$TYPE"'.value[]' | \
+        echo "$IPS_JSON" | \
+            jq '.value.value.'"$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}' | \
+            awk '{print "export __TYPE___" $1 "=" $2}' | \
             sed s/__TYPE__/$TYPE_UPPER/g
     done)"
 

From ec6bb824d0ff6ce8d0d6aec1e1000bf534d3f85b Mon Sep 17 00:00:00 2001
From: shnee <shnee@shnee.net>
Date: Thu, 18 Nov 2021 11:19:59 -0500
Subject: [PATCH 6/6] Moved node-config to be local, added AMI vars.

---
 example.tfvars | 13 -------------
 get-vm-ips.sh  |  1 +
 main.tf        | 22 ++++++++++++++++++----
 variables.tf   | 41 ++++++++++++++++++++++++++++++++++++-----
 4 files changed, 55 insertions(+), 22 deletions(-)

diff --git a/example.tfvars b/example.tfvars
index df3f604..41ca648 100644
--- a/example.tfvars
+++ b/example.tfvars
@@ -21,19 +21,6 @@ aws-ec2-instance-type = "t2.micro"
 # 4 GiB, 2 vcpus
 # aws-ec2-instnce-type = "t2.medium"
 
-################################################################################
-
-nodes-config = {
-  "master" = {
-    base-image = "ami-0dd0ccab7e2801812"
-    num = 1
-  },
-  "worker" = {
-    base-image = "ami-0dd0ccab7e2801812"
-    num = 2
-  }
-}
-
 ################################################################################
 # AWS images (AMIs)
 ################################################################################
diff --git a/get-vm-ips.sh b/get-vm-ips.sh
index 230b5cf..cbdc820 100755
--- a/get-vm-ips.sh
+++ b/get-vm-ips.sh
@@ -48,6 +48,7 @@ ANSIBLE_INV="$(
         sed -z 's/\n/,/g;s/,$/\n/g')"
 
 # Create an inventory file for ansible.
+echo "# Wrote an Ansible inventory file at ./inventory"
 echo "[k8s_nodes]" > inventory
 echo $VM_IP_EXPORTS | \
     sed 's/"//g' | \
diff --git a/main.tf b/main.tf
index 7510f3e..caa213c 100644
--- a/main.tf
+++ b/main.tf
@@ -8,12 +8,25 @@ terraform {
   }
 }
 
+locals {
+  nodes-config = {
+    "master" = {
+      base-image = var.amzn2-ami
+      num = 1
+    },
+    "worker" = {
+      base-image = var.amzn2-ami
+      num = 2
+    }
+  }
+}
+
 ################################################################################
 # cloud-init
 ################################################################################
 
 module "cloud-init-config" {
-  for_each            = var.nodes-config
+  for_each            = local.nodes-config
   source              = "./modules/cloud-init-config"
   cloud-init-template = "${path.module}/cloud_init.cfg"
   hostname-prefix     = "${var.vm-name-prefix}-${each.key}"
@@ -32,7 +45,8 @@ provider "aws" {
   region = "us-east-2"
 }
 
-# This module will grab the latest ami for a variety of distros.
+# 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" {
 #   source = "./modules/aws-amis"
 # }
@@ -59,7 +73,7 @@ resource "aws_key_pair" "key" {
 }
 
 module "nodes" {
-  for_each           = var.nodes-config
+  for_each           = local.nodes-config
   source             = "./modules/aws-nodes"
   ami                = each.value.base-image
   ec2-instance-type  = var.aws-ec2-instance-type
@@ -85,7 +99,7 @@ module "nodes" {
 # }
 # 
 # module "nodes" {
-#   for_each               = var.nodes-config
+#   for_each               = local.nodes-config
 #   source                 = "./modules/libvirt-nodes"
 #   pool-name              = libvirt_pool.images.name
 #   name-prefix            = "${var.vm-name-prefix}-${each.key}"
diff --git a/variables.tf b/variables.tf
index e8f3211..3719268 100644
--- a/variables.tf
+++ b/variables.tf
@@ -43,11 +43,6 @@ variable "node-vcpus" {
   type        = number
 }
 
-variable "nodes-config" {
-  description = "A config that declares how many nodes of each type you want created."
-  type = map(object({base-image=string,num=number}))
-}
-
 variable "root-admin-passwd" {
   description = "This will be the password for the root and admin user. The format of this can by any format accepted by cloud-init's chpasswd module."
 }
@@ -76,3 +71,39 @@ variable "vm-name-prefix" {
   default = "k8s-tf"
   description = "This prefix will appear before all VM names and hostnames, ie. k8s-tf-master-0."
 }
+
+################################################################################
+# AWS AMI vars
+# These variables are really mor like constants. Using variables improves
+# readability. The defaults are manually updated. Use the aws-amis module to get
+# the latest for each distro.
+################################################################################
+
+variable "amzn2-ami" {
+  default     = "ami-0dd0ccab7e2801812"
+  description = "The AMI to use for Amazon Linux 2."
+}
+variable "ubuntu-ami" {
+  default = "ami-06c7d6c0987eaa46c"
+  description = "The AMI to use for Ubuntu."
+}
+variable "centos7-ami" {
+  default = "ami-00f8e2c955f7ffa9b"
+  description = "The AMI to use for CentOS 7."
+}
+variable "centos8-ami" {
+  default = "ami-057cacbfbbb471bb3"
+  description = "The AMI to use for CentOS 8."
+}
+variable "arch-ami" {
+  default = "ami-02653f06de985e3ba"
+  description = "The AMI to use for Arch Linux."
+}
+variable "rhel7-ami" {
+  default = "ami-0a509b3c2a4d05b3f"
+  description = "The AMI to use for RHEL 7."
+}
+variable "rhel8-ami" {
+  default = "ami-0d871ca8a77af2948"
+  description = "The AMI to use for RHEL 8."
+}