data/aws: Encrypt the AMI used by the bootstrap and master machines

This is a quick hack to get encrypted masters.  Ideally we'd want to
deregister these on bootstrap-teardown, but handling that nicely will
be easier after some cleanups from [1].  As it stands, we'll
deregister this as part of the general cluster teardown.

Because we don't set kms_key_id [2] we get "the default AWS KMS Key"
(according to [2]).  AWS docs are not particularly clear about whether
users can configure the default key for their account/region to
override that default, although it is clear that it defaults to an
AWS-managed CMK [3] and that the alias for AMI encryption is
alias/aws/ebs [4].  If there is no way to override alias/aws/ebs,
we'll probably eventially need to expose kms_key_id to users.

[1]: #1148
[2]: https://www.terraform.io/docs/providers/aws/r/ami_copy.html#kms_key_id
[3]: https://docs.aws.amazon.com/kms/latest/developerguide/concepts.html#aws-managed-cmk
[4]: https://aws.amazon.com/blogs/security/how-to-create-a-custom-ami-with-encrypted-amazon-ebs-snapshots-and-share-it-with-other-accounts-and-regions/

data/data/aws/main.tf

@@ -11,7 +11,7 @@ provider "aws" {
 module "bootstrap" {
   source = "./bootstrap"
 
-  ami                      = "${var.aws_ec2_ami_override}"
+  ami                      = "${aws_ami_copy.main.id}"
   instance_type            = "${var.aws_bootstrap_instance_type}"
   cluster_id               = "${var.cluster_id}"
   ignition                 = "${var.ignition_bootstrap}"
@@ -40,7 +40,7 @@ module "masters" {
   subnet_ids               = "${module.vpc.private_subnet_ids}"
   target_group_arns        = "${module.vpc.aws_lb_target_group_arns}"
   target_group_arns_length = "${module.vpc.aws_lb_target_group_arns_length}"
-  ec2_ami                  = "${var.aws_ec2_ami_override}"
+  ec2_ami                  = "${aws_ami_copy.main.id}"
   user_data_ign            = "${var.ignition_master}"
 }
 
@@ -77,3 +77,16 @@ module "vpc" {
 
   tags = "${local.tags}"
 }
+
+resource "aws_ami_copy" "main" {
+  name              = "${var.cluster_id}-master"
+  source_ami_id     = "${var.aws_ami}"
+  source_ami_region = "${var.aws_region}"
+  encrypted         = true
+
+  tags = "${merge(map(
+    "Name", "${var.cluster_id}-master",
+    "sourceAMI": "${var.aws_ami}",
+    "sourceRegion": "${var.aws_region}",
+  ), local.tags)}"
+}

data/data/aws/variables-aws.tf

@@ -17,10 +17,9 @@ variable "aws_master_instance_type" {
   description = "Instance type for the master node(s). Example: `m4.large`."
 }
 
-variable "aws_ec2_ami_override" {
+variable "aws_ami" {
   type        = "string"
-  description = "(optional) AMI override for all nodes. Example: `ami-foobar123`."
-  default     = ""
+  description = "AMI for all nodes.  An encrypted copy of this AMI will be used.  Example: `ami-foobar123`."
 }
 
 variable "aws_extra_tags" {

docs/user/aws/install.md

@@ -33,6 +33,11 @@ INFO Access the OpenShift web-console here: https://console-openshift-console.ap
 INFO Login to the console with user: kubeadmin, password: XXXX
 ```
 
+This creates an encrypted AMI for the bootstrap and control-plane machines.
+The encrypted AMI is [copied][encrypted-copy] from the AMI configured in the control-plane machine-API provider spec, which is RHCOS by default.
+The encryption uses the default EBS key for your target account and region (`aws kms describe-key --key-id alias/aws/ebs`).
+The encrypted AMI is deregistered by `destroy cluster`.
+
 ### Running Cluster
 
 In Route53, there will be a new, private hosted zone (for internal lookups):
@@ -56,3 +61,4 @@ The OpenShift console is available via the kubeadmin login provided by the insta
 ![OpenShift web console](images/install_console.png)
 
 [cloud-install]: https://cloud.openshift.com/clusters/install
+[encrypted-copy]: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AMIEncryption.html#create-ami-encrypted-root-snapshot

pkg/destroy/aws/aws.go

@@ -455,6 +455,8 @@ func deleteEC2(session *session.Session, arn arn.ARN, logger logrus.FieldLogger)
 		return deleteEC2DHCPOptions(client, id, logger)
 	case "elastic-ip":
 		return deleteEC2ElasticIP(client, id, logger)
+	case "image":
+		return deleteEC2Image(client, id, logger)
 	case "instance":
 		return deleteEC2Instance(client, iam.New(session), id, logger)
 	case "internet-gateway":
@@ -491,6 +493,21 @@ func deleteEC2DHCPOptions(client *ec2.EC2, id string, logger logrus.FieldLogger)
 	return nil
 }
 
+func deleteEC2Image(client *ec2.EC2, id string, logger logrus.FieldLogger) error {
+	_, err := client.DeregisterImage(&ec2.DeregisterImageInput{
+		ImageId: &id,
+	})
+	if err != nil {
+		if err.(awserr.Error).Code() == "InvalidAMIID.NotFound" {
+			return nil
+		}
+		return err
+	}
+
+	logger.Info("Deleted")
+	return nil
+}
+
 func deleteEC2ElasticIP(client *ec2.EC2, id string, logger logrus.FieldLogger) error {
 	_, err := client.ReleaseAddress(&ec2.ReleaseAddressInput{
 		AllocationId: aws.String(id),

pkg/tfvars/aws/aws.go

@@ -11,7 +11,7 @@ import (
 )
 
 type config struct {
-	EC2AMIOverride        string            `json:"aws_ec2_ami_override,omitempty"`
+	AMI                   string            `json:"aws_ami"`
 	ExtraTags             map[string]string `json:"aws_extra_tags,omitempty"`
 	BootstrapInstanceType string            `json:"aws_bootstrap_instance_type,omitempty"`
 	MasterInstanceType    string            `json:"aws_master_instance_type,omitempty"`
@@ -52,9 +52,9 @@ func TFVars(masterConfig *v1beta1.AWSMachineProviderConfig) ([]byte, error) {
 	instanceClass := defaults.InstanceClass(masterConfig.Placement.Region)
 
 	cfg := &config{
-		Region:                masterConfig.Placement.Region,
-		ExtraTags:             tags,
-		EC2AMIOverride:        *masterConfig.AMI.ID,
+		Region:    masterConfig.Placement.Region,
+		ExtraTags: tags,
+		AMI:       *masterConfig.AMI.ID,
 		BootstrapInstanceType: fmt.Sprintf("%s.large", instanceClass),
 		MasterInstanceType:    masterConfig.InstanceType,
 		Size:                  *rootVolume.EBS.VolumeSize,