Terraform, is no doubt very flexible and powerful. The question is, how do we write Terraform code and construct our infrastructure in a reproducible fashion that makes sense? How can we keep code DRY, segment state, and reduce the risk of making changes to our service/stack/infrastructure? HashiCorp’s infrastructure management tool, Terraform, is no doubt very flexible and powerful. The question is, how do we write Terraform code and construct our infrastructure in a reproducible fashion that makes sense? How can we keep code DRY, segment state, and reduce the risk of making changes to our service/stack/infrastructure? This talk describes a design pattern to help answer the previous questions. The talk is divided into two sections, with the first section describing and defining the design pattern with a Deployment Example. The second part uses a multi-repository GitHub organization to create a Real World Example of the design pattern.

1. Terraform at Scale

2. ◉ Introduction
◉ Terraform at Scale?
◉ Gotta Keep ‘em Separated
◉ Reducing Complexity With Style
◉ A Tale of Two Modules
Introduction: Agenda and Takeaways

3. 80%
Percentage of Outages Caused by Changes*
* Source: Behr, K., Kim, G., & Spafford, G. (2013). The Visible Ops Handbook

4. Post-fordism, cognitive-cultural economy derived from spontaneous order.

6. Simple and Powerful
Source: terraform.io

7. Terraform Providers

8. Terraform Providers

9. Terraform at Scale?

10. Terraform at Scale?

11. Terraform at Scale?

12. Terraform at Scale?

13. Terraform at Scale?

14. Terraform at Scale?

15. Terraform at Scale?

16. Terraform at Scale?

17. Terraform at Scale?

18. Terraform at Scale?

19. Terraform at Scale?

20. Terraform at Scale?

21. Terraform at Scale?

22. This is fine.

23. Gotta Keep ‘em Separated

24. Dive In: Code Samples

25. AWS Provider
provider.tf
provider "aws" {
region = "us-east-1"
}

26. AWS Route53 Provisioners
route53.tf
resource "aws_route53_zone" "route53_zone" {
name = "devops-demo.xyz"
}
resource "aws_route53_record" "api_route53_record" {
zone_id = "${aws_route53_zone.route53_zone.zone_id}"
name = "dev-api.devops-demo.xyz"
type = "A"
ttl = "300"
records = ["86.75.30.9"]
}

27. AWS Route53 Provisioners
route53.tf
resource "aws_route53_zone" "route53_zone" {
name = "devops-demo.xyz"
}
resource "aws_route53_record" "api_route53_record" {
zone_id = "${aws_route53_zone.route53_zone.zone_id}"
name = "dev-api.devops-demo.xyz"
type = "A"
ttl = "300"
records = ["86.75.30.9"]
}

28. route53.tf
resource "aws_route53_zone" "route53_zone" {
name = "devops-demo.xyz"
}
resource "aws_route53_record" "api_route53_record" {
zone_id = "${aws_route53_zone.route53_zone.zone_id}"
name = "dev-api.devops-demo.xyz"
type = "A"
ttl = "300"
records = ["86.75.30.9"]
}
AWS Route53 Provisioners

29. route53.tf
resource "aws_route53_zone" "route53_zone" {
name = "devops-demo.xyz"
}
resource "aws_route53_record" "api_route53_record" {
zone_id = "${aws_route53_zone.route53_zone.zone_id}"
name = "dev-api.devops-demo.xyz"
type = "A"
ttl = "300"
records = ["86.75.30.9"]
}
AWS Route53 Provisioners

30. route53.tf
resource "aws_route53_zone" "route53_zone" {
name = "devops-demo.xyz"
}
resource "aws_route53_record" "api_route53_record" {
zone_id = "${aws_route53_zone.route53_zone.zone_id}"
name = "dev-api.devops-demo.xyz"
type = "A"
ttl = "300"
records = ["86.75.30.9"]
}
AWS Route53 Provisioners

31. terraform plan (console output)
+ aws_route53_record.api_route53_record
fqdn: "<computed>"
name: "dev-api.devops-demo.xyz"
records.#: "1"
records.4228697306: "86.75.30.9"
ttl: "300"
type: "A"
zone_id: "${aws_route53_zone.route53_zone.zone_id}"
+ aws_route53_zone.route53_zone
comment: "Managed by Terraform"
force_destroy: "false"
name: "devops-demo.xyz"
name_servers.#: "<computed>"
vpc_region: "<computed>"
zone_id: "<computed>"
Plan: 2 to add, 0 to change, 0 to destroy.

32. Root Module Example
providers.tf
route53.tf
Our First Module v1

33. outputs.tf
providers.tf
route53.tf
variables.tf
Congratulations On Your WET Module!
Image Source: “Campaign Shake-Up” Parks and Recreation, season 4, episode 17, NBC, 01 Mar. 2012

34. Parameterize To Stay DRY
provider.tf
provider "aws" {
region = "us-east-1"
}
route53.tf
resource "aws_route53_zone" "route53_zone" {
name = "devops-demo.xyz"
}
resource "aws_route53_record" "api_route53_record" {
zone_id = "${aws_route53_zone.route53_zone.zone_id}"
name = "dev-api.devops-demo.xyz"
type = "A"
ttl = "300"
records = ["86.75.30.9"]
}

35. Input Variables
provider.tf
provider "aws" {
region = "${var.aws_region}"
}
route53.tf
resource "aws_route53_zone" "route53_zone" {
name = "${var.domain_name}"
}
resource "aws_route53_record" "api_route53_record" {
zone_id = "${aws_route53_zone.route53_zone.zone_id}"
name = "${var.environment}-api.${var.domain_name}"
type = "A"
ttl = "300"
records = ["${var.ip_address}”]
}

36. variables.tf
variable "aws_account" {
default = "sysadvent-production"
}
variable "aws_region" {
default = "us-east-1"
}
variable "domain_name" {
default = "devops-demo.xyz"
}
variable "environment" {
default = "dev"
}
variable "ip_address" {
default = "86.75.30.9"
}

37. terraform apply (console output)
aws_route53_zone.route53_zone: Creating...
comment: "" => "Managed by Terraform"
force_destroy: "" => "false"
name: "" => "devops-demo.xyz"
name_servers.#: "" => "<computed>"
vpc_region: "" => "<computed>"
zone_id: "" => "<computed>"
aws_route53_zone.route53_zone: Creation complete (ID: Z3CIMZCT6RGERD)
aws_route53_record.api_route53_record: Creating...
fqdn: "" => "<computed>"
name: "" => "dev-api.devops-demo.xyz"
records.#: "" => "1"
records.4228697306: "" => "86.75.30.9"
ttl: "" => "300"
type: "" => "A"
zone_id: "" => "Z3QZEABS9HJLIN"
aws_route53_record.api_route53_record: Creation complete (ID: Z3CIMZCT6RGERD_api.devops-demo.xyz_A)
...

38. terraform apply (console output cont.)
...
Apply complete! Resources: 2 added, 0 changed, 0 destroyed.
The state of your infrastructure has been saved to the path
below. This state is required to modify and destroy your
infrastructure, so keep it safe. To inspect the complete state
use the `terraform show` command.
State path:
Outputs:
api_fqdn = dev-api.devops-demo.xyz
domain_name = devops-demo.xyz
zone_id = Z3QZEABS9HJLIN

40. terraform apply (console output cont.)
...
Apply complete! Resources: 2 added, 0 changed, 0 destroyed.
The state of your infrastructure has been saved to the path
below. This state is required to modify and destroy your
infrastructure, so keep it safe. To inspect the complete state
use the `terraform show` command.
State path:
Outputs:
api_fqdn = dev-api.devops-demo.xyz
domain_name = devops-demo.xyz
zone_id = Z3QZEABS9HJLIN

41. outputs.tf
output "api_fqdn" {
value = "${aws_route53_record.api_route53_record.fqdn}"
}
output "domain_name" {
value = "${var.domain_name}"
}
output "zone_id" {
value = "${aws_route53_zone.route53_zone.id}"
}
Output Variables

42. outputs.tf
output "api_fqdn" {
value = "${aws_route53_record.api_route53_record.fqdn}"
}
output "domain_name" {
value = "${var.domain_name}"
}
output "zone_id" {
value = "${aws_route53_zone.route53_zone.id}"
}
Output Variables

43. outputs.tf
output "api_fqdn" {
value = "${aws_route53_record.api_route53_record.fqdn}"
}
output "domain_name" {
value = "${var.domain_name}"
}
output "zone_id" {
value = "${aws_route53_zone.route53_zone.id}"
}
Output Variables

44. Root Module Example
outputs.tf
providers.tf
route53.tf
variables.tf
Our First Module v2

45. Reducing Complexity
With Style

46. eip.tf
internet_gateway.tf
nat_gateway.tf
outputs.tf
providers.tf
route.tf
subnets.tf
variables.tf
vpc.tf
Naming Conventions: File Names

47. Naming Conventions: Resource Names
◉ RESOURCE NAME = RESOURCE TYPE - PROVIDER NAME
resource "aws_security_group" "security_group" {
name = "${var.resource_name}-security-group"
...

48. Naming Conventions: Resource Names (cont.)
resource "aws_s3_bucket" "data_s3_bucket" {
bucket = "${var.env}-data-${var.aws_region}"
}
resource "aws_s3_bucket" "images_s3_bucket" {
bucket = "${var.env}-images-${var.aws_region}"
}
◉ Multiple resources of the same TYPE should have a minimalistic identifier to
differentiate between the two resources.

49. When to Use an Underscore
resource "aws_route53_record" "api_route53_record" {
zone_id = "${aws_route53_zone.route53_zone.zone_id}"
name = "${var.environment}-api.${var.domain_name}"
type = "A"
ttl = "300"
records = ["${var.ip_address}"]
}
◉ Variable Names
◉ Resource Names
◉ Anything Interpolated

50. When to Use a Hyphen
resource "aws_route53_record" "api_route53_record" {
zone_id = "${aws_route53_zone.route53_zone.zone_id}"
name = "${var.environment}-api.${var.domain_name}"
type = "A"
ttl = "300"
records = ["${var.ip_address}"]
}
◉ Resources Being Created

51. Source: terraform.io

52. Source: terraform.io

54. A Tale of Two Modules

55. Service Module
● Reusable library
● Creates all required resources a service needs to be operational i.e. EC2
instances, S3 bucket, DNS Entries
A Tale of Two Modules
Infrastructure Module
● Single repository comprised of multiple root modules
● This is where Service Modules are instantiated/Terraform is run.

56. Why Infrastructure Modules?
◉ Conditional Statements
○ Don’t exist Are painful (1604)
◉ Segment State
○ Reduce risk of changes
○ Flexible state reference
◉ DRY Terraform Configurations
○ Instantiate reusable modules
◉ Environments Aren’t Recommended (0.9)
◉ Workspaces are a thing (renamed statefile)

57. The Candle Problem
Source: http://whatismotivation.weebly.com/uploads/2/9/9/1/29913749/1713129_orig.png

58. Overcome Functional Fixedness
Source: http://whatismotivation.weebly.com/uploads/2/9/9/1/29913749/1713129_orig.png

59. https://kvaes.wordpress.com/2013/06/05/lingo-explained-greenfield-vs-brownfield/
Terraform: Configuration by Convention

60. Configuration by Convention
Infrastructure Repository Folder Structure
AWS (provider)
|__ production-account (aws-account root module)
|__ us-east-1 (aws-region root module)
|__ production-us-east-1-vpc (vpc root module)
|__ production (environment root module)
|__ inf-bastion (service root module)

61. Account Root Module
Infrastructure Repository Folder Structure
AWS (provider)
|__ production-account (aws-account root module) <~~~~~ YOU ARE HERE
|__ us-east-1 (aws-region root module)
|__ production-us-east-1-vpc (vpc root module)
|__ production (environment root module)
|__ inf-bastion (service root module)

62. terraform.sh (bash wrapper)
Usage: ./templates/account-terraform.sh [apply|destroy|plan|refresh|show]
The following arguments are supported:
apply Refresh the Terraform remote state, "terraform get -update", and "terraform apply"
destroy Refresh the Terraform remote state and destroy the Terraform stack
plan Refresh the Terraform remote state, "terraform get -update", and "terraform plan"
refresh Refresh the Terraform remote state
show Refresh and show the Terraform remote state

63. Refresh Function
...
refresh() {
root=$(pwd | awk -F "/" '{print $(NF-1)}')
aws_account=$(pwd | awk -F "/" '{print $NF}')
export TF_VAR_root="$root"
export TF_VAR_aws_account="$aws_account"
export TF_PLUGIN_CACHE_DIR="~/.terraform.d/plugin-cache"
echo -e "nn***** Refreshing State and Upgrading Modules *****"
echo "no" | terraform init -get=true
-upgrade
-input=false
-backend=true
-backend-config "bucket=${aws_account}-terraform-state"
-backend-config "key=${root}/terraform.tfstate"
-backend-config "profile=${aws_account}"
-backend-config "region=us-east-1"
}
...

64. Refresh Function
...
refresh() {
root=$(pwd | awk -F "/" '{print $(NF-1)}')
aws_account=$(pwd | awk -F "/" '{print $NF}')
export TF_VAR_root="$root"
export TF_VAR_aws_account="$aws_account"
export TF_PLUGIN_CACHE_DIR="~/.terraform.d/plugin-cache"
echo -e "nn***** Refreshing State and Upgrading Modules *****"
echo "no" | terraform init -get=true
-upgrade
-input=false
-backend=true
-backend-config "bucket=${aws_account}-terraform-state"
-backend-config "key=${root}/terraform.tfstate"
-backend-config "profile=${aws_account}"
-backend-config "region=us-east-1"
}
...

65. Refresh Function
...
refresh() {
root=$(pwd | awk -F "/" '{print $(NF-1)}')
aws_account=$(pwd | awk -F "/" '{print $NF}')
export TF_VAR_root="$root"
export TF_VAR_aws_account="$aws_account"
export TF_PLUGIN_CACHE_DIR="~/.terraform.d/plugin-cache"
echo -e "nn***** Refreshing State and Upgrading Modules *****"
echo "no" | terraform init -get=true
-upgrade
-input=false
-backend=true
-backend-config "bucket=${aws_account}-terraform-state"
-backend-config "key=${root}/terraform.tfstate"
-backend-config "profile=${aws_account}"
-backend-config "region=us-east-1"
}
...

66. ...
createBackendConfig() {
/bin/cat > backend.tf <<EOL
terraform {
backend "s3" {}
}
EOL
}
...
Create Backend Config
backend.tf
terraform {
backend "s3" {}
}

67. Account Root Module
backend.tf
outputs.tf
providers.tf
terraform.sh
route53.tf
variables.tf
Our First Module v3

68. AWS-Region Root Module
Infrastructure Repository Folder Structure
AWS (provider)
|__ production-account (aws-account root module)
|__ us-east-1 (aws-region root module) <~~~~~ PLACEHOLDER
|__ production-us-east-1-vpc (vpc root module)
|__ production (environment root module)
|__ inf-bastion (service root module)

69. VPC Root Module
Infrastructure Repository Folder Structure
AWS (provider)
|__ production-account (aws-account root module)
|__ us-east-1 (aws-region root module)
|__ production-us-east-1-vpc (vpc root module) <~~~~~ YOU ARE HERE
|__ production (environment root module)
|__ inf-bastion (service root module)

70. VPC Root Module
backend.tf
main.tf
outputs.tf
terraform.sh
variables.tf
VPC Root Module (cont.)

71. main.tf
module "vpc" {
source = "git@github.com:TerraformDesignPattern/vpc.git?ref=1.2.3"
availability_zones = "${var.availability_zones}"
aws_region = "${var.aws_region}"
private_subnets = "${var.private_subnets}"
public_subnets = "${var.public_subnets}"
vpc_cidr = "${var.vpc_cidr}"
vpc_name = "${var.vpc_name}"
}
VPC Root Module (cont.)

72. main.tf
module "vpc" {
source = "git@github.com:TerraformDesignPattern/vpc.git?ref=1.2.3"
availability_zones = "${var.availability_zones}"
aws_region = "${var.aws_region}"
private_subnets = "${var.private_subnets}"
public_subnets = "${var.public_subnets}"
vpc_cidr = "${var.vpc_cidr}"
vpc_name = "${var.vpc_name}"
}
VPC Root Module (cont.)

73. main.tf
module "vpc" {
source = "git@github.com:TerraformDesignPattern/vpc.git?ref=${var.branch}"
availability_zones = "${var.availability_zones}"
aws_region = "${var.aws_region}"
private_subnets = "${var.private_subnets}"
public_subnets = "${var.public_subnets}"
vpc_cidr = "${var.vpc_cidr}"
vpc_name = "${var.vpc_name}"
}
VPC Root Module (cont.)

74. NOPE.

75. main.tf
module "vpc" {
source = "git@github.com:TerraformDesignPattern/vpc.git?ref=${var.branch}"
availability_zones = "${var.availability_zones}"
aws_region = "${var.aws_region}"
private_subnets = "${var.private_subnets}"
public_subnets = "${var.public_subnets}"
vpc_cidr = "${var.vpc_cidr}"
vpc_name = "${var.vpc_name}"
}
VPC Root Module (cont.)
No interpolation allowed!
Issue #1439

77. main.tf
module "vpc" {
source = "git@github.com:TerraformDesignPattern/vpc.git?ref=${var.branch}"
availability_zones = "${var.availability_zones}"
aws_region = "${var.aws_region}"
private_subnets = "${var.private_subnets}"
public_subnets = "${var.public_subnets}"
vpc_cidr = "${var.vpc_cidr}"
vpc_name = "${var.vpc_name}"
}
VPC Root Module (cont.)
No interpolation allowed!
Issue #1439

78. NOPE.

80. Soon.

81. Maybe?

82. main.tf
module "vpc" {
source = "git@github.com:TerraformDesignPattern/vpc.git?ref=1.2.3"
availability_zones = "${var.availability_zones}"
aws_region = "${var.aws_region}"
private_subnets = "${var.private_subnets}"
public_subnets = "${var.public_subnets}"
vpc_cidr = "${var.vpc_cidr}"
vpc_name = "${var.vpc_name}"
}
VPC Root Module (cont.)

83. VPC Root Module
backend.tf
main.tf
outputs.tf
terraform.sh
variables.tf
VPC Root Module (cont.)

84. variables.tf
...
variable "public_subnets" {
default = [
"172.19.101.0/24",
"172.19.102.0/24",
"172.19.103.0/24",
]
}
...
VPC Root Module (cont.)

85. VPC Module Repository
eip.tf
internet_gateway.tf
nat_gateway.tf
outputs.tf
providers.tf
route.tf
subnets.tf
variables.tf
vpc.tf
VPC Service Module

86. outputs.tf
...
output "public_subnet_ids" {
value = ["${aws_subnet.public_subnet.*.id}"]
}
...
VPC Service Module Outputs

87. outputs.tf
...
output "public_subnet_ids" {
value = ["${module.vpc.public_subnet_ids}"]
}
...
VPC Root Module Outputs

89. To Begin Again... From The Beginning
Quote: Waking Life. Dir. Richard Linklater. Fox Searchlight Pictures, 2001. FIlm.
Image: Fight Club. Dir. David Fincher. 20th Century Fox, 1999. Film.

90. s3.tf
resource "aws_s3_bucket_object" "outputs_object" {
bucket = "${var.aws_account}-terraform-state"
key =
"aws/${var.aws_region}/${var.vpc_name}/dummy_object_outputs"
source = "outputs.tf"
etag = "${md5(file("outputs.tf"))}"
}
resource "aws_s3_bucket_object" "variables_object" {
bucket = "${var.aws_account}-terraform-state"
key =
"aws/${var.aws_region}/${var.vpc_name}/dummy_object_variables"
source = "variables.tf"
etag = "${md5(file("variables.tf"))}"
}
Root Module State Seeding
outputs.tf
output "public_subnet_ids" {
value = ["${var.public_subnets}"]
}
...
variables.tf
variable "public_subnets" {
default = [
"172.19.101.0/24",
"172.19.102.0/24",
"172.19.103.0/24",
]
}
...

91. Environment Root Module
Infrastructure Repository Folder Structure
AWS (provider)
|__ production-account (aws-account root module)
|__ us-east-1 (aws-region root module)
|__ production-us-east-1-vpc (vpc root module)
|__ production (environment root module) <~~~~~ PLACEHOLDER
|__ inf-bastion (service root module)

92. http://kristinvogel.edublogs.org/files/2014/04/home-stretch-ouwf9k.jpg

93. Service Root Module
Infrastructure Repository Folder Structure
AWS (provider)
|__ production-account (aws-account root module)
|__ us-east-1 (aws-region root module)
|__ production-us-east-1-vpc (vpc root module)
|__ production (environment root module)
|__ inf-bastion (service root module) <~~~~~ YOU ARE HERE

94. SSH Bastion Root Module
backend.tf
main.tf
outputs.tf
terraform.sh
variables.tf
SSH Bastion Root Module

95. variables.tf
variable "aws_account" {}
variable "aws_region" {}
variable "aws_environment_name" {}
variable "service_name" {}
variable "vpc_name" {}
SSH Bastion Root Module (cont.)

96. refresh() {
root=$(pwd | awk -F "/" '{print $(NF-5)}')
aws_account=$(pwd | awk -F "/" '{print $(NF-4)}')
aws_region=$(pwd | awk -F "/" '{print $(NF-3)}')
vpc_name=$(pwd | awk -F "/" '{print $(NF-2)}')
environment_name=$(pwd | awk -F "/" '{print $(NF-1)}')
service_name=$(pwd | awk -F "/" '{print $NF}')
bucket_key="${root}/${aws_region}/${vpc_name}/${environment_name}/${service_name}"
export TF_VAR_root="$root"
export TF_VAR_aws_account="$aws_account"
export TF_VAR_aws_region="$aws_region"
export TF_VAR_vpc_name="$vpc_name"
export TF_VAR_environment_name="$environment_name"
export TF_VAR_service_name="$service_name"
export TF_PLUGIN_CACHE_DIR="~/.terraform.d/plugin-cache"
echo -e "nn***** Refreshing State and Upgrading Modules *****"
echo "no" | terraform init -get=true
-upgrade
-input=false
-backend=true
-backend-config "bucket=${aws_account}-terraform-state"
-backend-config "key=${bucket_key}/terraform.tfstate"
-backend-config "profile=${aws_account}"
-backend-config "region=us-east-1"
}
Refresh Function

97. refresh() {
root=$(pwd | awk -F "/" '{print $(NF-5)}')
aws_account=$(pwd | awk -F "/" '{print $(NF-4)}')
aws_region=$(pwd | awk -F "/" '{print $(NF-3)}')
vpc_name=$(pwd | awk -F "/" '{print $(NF-2)}')
environment_name=$(pwd | awk -F "/" '{print $(NF-1)}')
service_name=$(pwd | awk -F "/" '{print $NF}')
bucket_key="${root}/${aws_region}/${vpc_name}/${environment_name}/${service_name}"
export TF_VAR_root="$root"
export TF_VAR_aws_account="$aws_account"
export TF_VAR_aws_region="$aws_region"
export TF_VAR_vpc_name="$vpc_name"
export TF_VAR_environment_name="$environment_name"
export TF_VAR_service_name="$service_name"
export TF_PLUGIN_CACHE_DIR="~/.terraform.d/plugin-cache"
echo -e "nn***** Refreshing State and Upgrading Modules *****"
echo "no" | terraform init -get=true
-upgrade
-input=false
-backend=true
-backend-config "bucket=${aws_account}-terraform-state"
-backend-config "key=${bucket_key}/terraform.tfstate"
-backend-config "profile=${aws_account}"
-backend-config "region=us-east-1"
}
Refresh Function

98. refresh() {
root=$(pwd | awk -F "/" '{print $(NF-5)}')
aws_account=$(pwd | awk -F "/" '{print $(NF-4)}')
aws_region=$(pwd | awk -F "/" '{print $(NF-3)}')
vpc_name=$(pwd | awk -F "/" '{print $(NF-2)}')
environment_name=$(pwd | awk -F "/" '{print $(NF-1)}')
service_name=$(pwd | awk -F "/" '{print $NF}')
bucket_key="${root}/${aws_region}/${vpc_name}/${environment_name}/${service_name}"
export TF_VAR_root="$root"
export TF_VAR_aws_account="$aws_account"
export TF_VAR_aws_region="$aws_region"
export TF_VAR_vpc_name="$vpc_name"
export TF_VAR_environment_name="$environment_name"
export TF_VAR_service_name="$service_name"
export TF_PLUGIN_CACHE_DIR="~/.terraform.d/plugin-cache"
echo -e "nn***** Refreshing State and Upgrading Modules *****"
echo "no" | terraform init -get=true
-upgrade
-input=false
-backend=true
-backend-config "bucket=${aws_account}-terraform-state"
-backend-config "key=${bucket_key}/terraform.tfstate"
-backend-config "profile=${aws_account}"
-backend-config "region=us-east-1"
}
Refresh Function

99. refresh() {
root=$(pwd | awk -F "/" '{print $(NF-5)}')
aws_account=$(pwd | awk -F "/" '{print $(NF-4)}')
aws_region=$(pwd | awk -F "/" '{print $(NF-3)}')
vpc_name=$(pwd | awk -F "/" '{print $(NF-2)}')
environment_name=$(pwd | awk -F "/" '{print $(NF-1)}')
service_name=$(pwd | awk -F "/" '{print $NF}')
bucket_key="${root}/${aws_region}/${vpc_name}/${environment_name}/${service_name}"
export TF_VAR_root="$root"
export TF_VAR_aws_account="$aws_account"
export TF_VAR_aws_region="$aws_region"
export TF_VAR_vpc_name="$vpc_name"
export TF_VAR_environment_name="$environment_name"
export TF_VAR_service_name="$service_name"
export TF_PLUGIN_CACHE_DIR="~/.terraform.d/plugin-cache"
echo -e "nn***** Refreshing State and Upgrading Modules *****"
echo "no" | terraform init -get=true
-upgrade
-input=false
-backend=true
-backend-config "bucket=${aws_account}-terraform-state"
-backend-config "key=${bucket_key}/terraform.tfstate"
-backend-config "profile=${aws_account}"
-backend-config "region=us-east-1"
}
Refresh Function

100. refresh() {
root=$(pwd | awk -F "/" '{print $(NF-5)}')
aws_account=$(pwd | awk -F "/" '{print $(NF-4)}')
aws_region=$(pwd | awk -F "/" '{print $(NF-3)}')
vpc_name=$(pwd | awk -F "/" '{print $(NF-2)}')
environment_name=$(pwd | awk -F "/" '{print $(NF-1)}')
service_name=$(pwd | awk -F "/" '{print $NF}')
bucket_key="${root}/${aws_region}/${vpc_name}/${environment_name}/${service_name}"
export TF_VAR_root="$root"
export TF_VAR_aws_account="$aws_account"
export TF_VAR_aws_region="$aws_region"
export TF_VAR_vpc_name="$vpc_name"
export TF_VAR_environment_name="$environment_name"
export TF_VAR_service_name="$service_name"
export TF_PLUGIN_CACHE_DIR="~/.terraform.d/plugin-cache"
echo -e "nn***** Refreshing State and Upgrading Modules *****"
echo "no" | terraform init -get=true
-upgrade
-input=false
-backend=true
-backend-config "bucket=${aws_account}-terraform-state"
-backend-config "key=${bucket_key}/terraform.tfstate"
-backend-config "profile=${aws_account}"
-backend-config "region=us-east-1"
}
Refresh Function

101. refresh() {
root=$(pwd | awk -F "/" '{print $(NF-5)}')
aws_account=$(pwd | awk -F "/" '{print $(NF-4)}')
aws_region=$(pwd | awk -F "/" '{print $(NF-3)}')
vpc_name=$(pwd | awk -F "/" '{print $(NF-2)}')
environment_name=$(pwd | awk -F "/" '{print $(NF-1)}')
service_name=$(pwd | awk -F "/" '{print $NF}')
bucket_key="${root}/${aws_region}/${vpc_name}/${environment_name}/${service_name}"
export TF_VAR_root="$root"
export TF_VAR_aws_account="$aws_account"
export TF_VAR_aws_region="$aws_region"
export TF_VAR_vpc_name="$vpc_name"
export TF_VAR_environment_name="$environment_name"
export TF_VAR_service_name="$service_name"
export TF_PLUGIN_CACHE_DIR="~/.terraform.d/plugin-cache"
echo -e "nn***** Refreshing State and Upgrading Modules *****"
echo "no" | terraform init -get=true
-upgrade
-input=false
-backend=true
-backend-config "bucket=${aws_account}-terraform-state"
-backend-config "key=${bucket_key}/terraform.tfstate"
-backend-config "profile=${aws_account}"
-backend-config "region=us-east-1"
}
Refresh Function

102. module “bastion" {
source = "git@github.com:TerraformDesignPattern/bastionhost.git?ref=0.1.0"
aws_account = "${var.aws_account}"
aws_region = "${var.aws_region}"
environment_name = "${var.environment_name}"
vpc_name = "${var.vpc_name}"
service_name = "${element(split("-", var.service_name), 0)}"
tier_name = "${element(split("-", var.service_name), 1)}"
}
SSH Bastion Root Module (cont.)

103. SSH Bastion Module Repository
data.tf
ec2.tf
outputs.tf
providers.tf
route53.tf
security_groups.tf
variables.tf
SSH Bastion Service Module

104. data.tf
data "terraform_remote_state" "account" {
backend = "s3"
config {
bucket = "${var.aws_account}-terraform-state"
key = "aws/terraform.tfstate"
region = "us-east-1"
}
}
data "terraform_remote_state" "vpc" {
backend = "s3"
config {
bucket = "${var.aws_account}-terraform-state"
key = "aws/${var.aws_region}/${var.vpc_name}/terraform.tfstate"
region = "us-east-1"
}
}

105. route53.tf
resource "aws_route53_record" "route53_record" {
zone_id = "${data.terraform_remote_state.account.zone_id}"
name = "${local.hostname}.${data.terraform_remote_state.account.domain_name}"
type = "A"
ttl = "300"
records = ["${aws_instance.instance.public_ip}"]
}
...
security_groups.tf
resource "aws_security_group" "elb_security_group" {
name = "${local.resource_name}-elb-sg-${data.terraform_remote_state.vpc.aws_region_shortname}"
vpc_id = "${data.terraform_remote_state.vpc.vpc_id}"
...

106. route53.tf
resource "aws_route53_record" "route53_record" {
zone_id = "${data.terraform_remote_state.account.zone_id}"
name = "${local.hostname}.${data.terraform_remote_state.account.domain_name}"
type = "A"
ttl = "300"
records = ["${aws_instance.instance.public_ip}"]
}
...
security_groups.tf
resource "aws_security_group" "elb_security_group" {
name = "${local.resource_name}-elb-sg-${data.terraform_remote_state.vpc.aws_region_shortname}"
vpc_id = "${data.terraform_remote_state.vpc.vpc_id}"
...

107. variables.tf
locals {
hostname = "${var.environment_name}-${var.service_name}-${var.tier}-${data.terraform_remote_state.vpc.aws_region_shortname}"
resource_name = "${var.environment_name}-${var.service_name}-${var.tier}"
}
...
Module “Local” Variables

108. Manage State & Variables Dynamically
Infrastructure Repository Folder Structure
AWS (provider)
|__ production-account (root aws-account module)
|__ us-east-1 (root aws-region module)
|__ production-us-east-1-vpc (root vpc module)
|__ production (root environment module)
|__ bastion (root service module)

109. ◉ Introduction
◉ Terraform at Scale?
◉ Gotta Keep ‘em Separated
◉ Reducing Complexity With Style
◉ A Tale of Two Modules
Closing: Agenda and Takeaways

111. Contact:
◉ Twitter: @jonbrouse
◉ Github: github.com/jonbrouse
◉ Site: jonbrouse.com
◉ github.com/TerraformDesignPattern
Thank you!
Jon Brouse