Commit finalized Terraform configuration

Commit finalized Terraform configuration using CentOS and CentOS Atomic Host images for working with an SSH bastion host

Signed-off-by: Scott Lowe <scott.lowe@scottlowe.org>

terraform/aws/bastion-aws/data.tf

@@ -1,13 +1,25 @@
 data "aws_ami" "atomic_ami" {
+    most_recent             = true
+    owners                  = ["410186602215"]
     filter {
         name                = "name"
-        values              = ["*CentOS Atomic*1701*"]
+        values              = ["CentOS Atomic Host 7*"]
+    }
+    filter {
+        name                = "virtualization-type"
+        values              = ["hvm"]
     }
 }
 
 data "aws_ami" "centos_ami" {
+    most_recent             = true
+    owners                  = ["410186602215"]
     filter {
         name                = "name"
-        values              = ["*CentOS 7.3.1611*"]
+        values              = ["CentOS Linux 7*"]
+    }
+    filter {
+        name                = "virtualization-type"
+        values              = ["hvm"]
     }
 }

terraform/aws/bastion-aws/instances.tf

@@ -7,22 +7,24 @@ resource "aws_instance" "bastion" {
     subnet_id                   = "${aws_subnet.bastion_net.id}"
     depends_on                  = ["aws_internet_gateway.bastion_gw"]
     tags {
+        Name                    = "bastion"
         tool                    = "terraform"
         demo                    = "bastion-aws"
         area                    = "instances"
     }
 }
 
-# Launch a second CentOS instance to serve as a remote host
-resource "aws_instance" "remote" {
-    ami                         = "${data.aws_ami.centos_ami.id}"
+# Launch a CentOS Atomic Host instance to serve as a private host
+resource "aws_instance" "private" {
+    ami                         = "${data.aws_ami.atomic_ami.id}"
     instance_type               = "${var.flavor}"
     key_name                    = "${var.keypair}"
-    vpc_security_group_ids      = ["${aws_security_group.remote_sg.id}"]
-    subnet_id                   = "${aws_subnet.bastion_net.id}"
+    vpc_security_group_ids      = ["${aws_security_group.private_sg.id}"]
+    subnet_id                   = "${aws_subnet.private_net.id}"
     depends_on                  = ["aws_internet_gateway.bastion_gw"]
     associate_public_ip_address = false
     tags {
+        Name                    = "private"
         tool                    = "terraform"
         demo                    = "bastion-aws"
         area                    = "instances"

terraform/aws/bastion-aws/networking.tf

@@ -1,8 +1,8 @@
 # Create a new VPC
 resource "aws_vpc" "bastion_vpc" {
     cidr_block              = "10.2.0.0/16"
-    enable_dns_hostnames    = "true"
-    enable_dns_support      = "true"
+    enable_dns_hostnames    = true
+    enable_dns_support      = true
     tags {
         tool                = "terraform"
         demo                = "bastion-aws"
@@ -14,7 +14,19 @@ resource "aws_vpc" "bastion_vpc" {
 resource "aws_subnet" "bastion_net" {
     vpc_id                  = "${aws_vpc.bastion_vpc.id}"
     cidr_block              = "10.2.1.0/24"
-    map_public_ip_on_launch = "true"
+    map_public_ip_on_launch = true
+    tags {
+        tool                = "terraform"
+        demo                = "bastion-aws"
+        area                = "networking"
+    }
+}
+
+# Create a private subnet in the new VPC
+resource "aws_subnet" "private_net" {
+    vpc_id                  = "${aws_vpc.bastion_vpc.id}"
+    cidr_block              = "10.2.2.0/24"
+    map_public_ip_on_launch = false
     tags {
         tool                = "terraform"
         demo                = "bastion-aws"

terraform/aws/bastion-aws/output.tf

@@ -7,5 +7,5 @@ output "bastion_priv_ip" {
 }
 
 output "remote_priv_ip" {
-    value = ["${aws_instance.remote.private_ip}"]
+    value = ["${aws_instance.private.private_ip}"]
 }

terraform/aws/bastion-aws/security.tf

@@ -1,25 +1,13 @@
-# Create a security group to allow web traffic to remote host
-resource "aws_security_group" "remote_sg" {
+# Create a security group to allow SSH traffic to private host(s) only from bastion
+resource "aws_security_group" "private_sg" {
     vpc_id                  = "${aws_vpc.bastion_vpc.id}"
-    name                    = "remote-sg"
-    description             = "Security group for web traffic to remote hosts"
-    ingress {
-        from_port           = "80"
-        to_port             = "80"
-        protocol            = "tcp"
-        cidr_blocks         = ["0.0.0.0/0"]
-    }
-    ingress {
-        from_port           = "443"
-        to_port             = "443"
-        protocol            = "tcp"
-        cidr_blocks         = ["0.0.0.0/0"]
-    }
+    name                    = "private-sg"
+    description             = "Security group for web traffic to private hosts"
     ingress {
         from_port           = "22"
         to_port             = "22"
         protocol            = "tcp"
-        cidr_blocks         = ["${aws_vpc.bastion_vpc.cidr_block}"]
+        cidr_blocks         = ["10.2.1.0/24"]
     }
     egress {
         from_port           = "0"

terraform/aws/bastion-aws/vars.tf

@@ -1,11 +1,9 @@
 variable "keypair" {
     type                    = "string"
     description             = "AWS SSH keypair to use to connect to instances"
-    default                 = "aws_rsa"
 }
 
 variable "flavor" {
     type                    = "string"
     description             = "AWS type to use when creating instances"
-    default                 = "t2.micro"
 }