terraform-aws-arc-billing

Introduction

SourceFuse's AWS Reference Architecture (ARC) Terraform module streamlines budget management and billing alarms in AWS environments. With predefined budgets and real-time Slack and email alerts, organizations stay on top of spending trends and prevent cost overruns. This proactive approach optimizes resource usage and ensures financial transparency across cloud deployments.

Prerequisites

Before using this module, ensure you have the following:

• AWS credentials configured.
• Terraform installed.
• A working knowledge of Terraform.
• IAM billing role

Getting Started

1. Define the Module

Initially, it's essential to define a Terraform module, which is organized as a distinct directory encompassing Terraform configuration files. Within this module directory, input variables and output values must be defined in the variables.tf and outputs.tf files, respectively. The following illustrates an example directory structure:

billing/
|-- main.tf
|-- variables.tf
|-- outputs.tf

1. Define Input Variables

Inside the variables.tf or in *.tfvars file, you should define values for the variables that the module requires.

1. Use the Module in Your Main Configuration In your main Terraform configuration file (e.g., main.tf), you can use the module. Specify the source of the module, and version, For Example

module "example_budgets" {
  source      = "sourcefuse/arc-billing/aws"
  version     = "0.0.1"

  namespace   = var.namespace
  environment = var.environment

  budgets = var.budgets

  notifications_enabled = var.notifications_enabled
  encryption_enabled    = var.encryption_enabled

  slack_webhook_url = var.slack_webhook_url
  slack_channel     = var.slack_channel
  slack_username    = var.slack_username

  billing_alerts_sns_subscribers = var.billing_alerts_sns_subscribers
}

1. Output Values

Inside the outputs.tf file of the module, you can define output values that can be referenced in the main configuration. For example:

output "sns_topic_name" {
  value       = module.budgets.sns_topic_name
}

output "lambda_function_arn" {
  value       = module.budgets.lambda_function_arn
}

1. .tfvars

Inside the .tfvars file of the module, you can provide desired values that can be referenced in the main configuration. For example:

Edit the dev.tfvars file and provide desired values.
The budgets variable is used to define list billing budgets to be managed by terraform
This module sends notifications to both slack and email.
Use the billing_notification_emails, to pass emails that will receive the billing alarms

region      = "us-east-1"
namespace   = "arc"
environment = "dev"

budgets = [
  {
    name            = "ec2-monthly-budget-50"
    budget_type     = "COST"
    limit_amount    = "50"
    limit_unit      = "USD"
    time_period_end = "2025-06-15_00:00"
    time_unit       = "MONTHLY"

    cost_filter = {
      Service = ["Amazon Elastic Compute Cloud - Compute"]
    }

    cost_types = {
      include_discount           = true
      include_other_subscription = true
      include_recurring          = true
      include_subscription       = true
      include_tax                = true
      include_upfront            = true
      include_support            = true
      include_refund             = false
      include_credit             = false
      use_blended                = false
    }

    notification = {
      comparison_operator        = "GREATER_THAN"
      threshold                  = "100"
      threshold_type             = "PERCENTAGE"
      notification_type          = "ACTUAL"
      subscriber_email_addresses = ["example@example-email.com"]
    }
  },
  {
    name         = "total-monthly-100"
    budget_type  = "COST"
    limit_amount = "100"
    limit_unit   = "USD"
    time_unit    = "MONTHLY"

    notification = {
      comparison_operator        = "GREATER_THAN"
      threshold                  = "100"
      threshold_type             = "PERCENTAGE"
      notification_type          = "ACTUAL"
      subscriber_email_addresses = ["example@example-email.com"]
    }
  }
]

encryption_enabled    = true
notifications_enabled = true
slack_webhook_url     = null
slack_channel         = null
slack_username        = null

billing_alerts_sns_subscribers = {
  "opsgenie" = {
    protocol               = "https"
    endpoint               = "https://api.opsgenie.com/v1/json/amazonsns?apiKey=xxxx-xxx-xx-xxx-xxxxxx"
    endpoint_auto_confirms = true
    raw_message_delivery   = false
  }
}

First Time Usage

uncomment the backend block in main.tf

terraform init -backend-config=config.dev.hcl

If testing locally, terraform init should be fine

Create a dev workspace

terraform workspace new dev

Plan Terraform

terraform plan -var-file dev.tfvars

Apply Terraform

terraform apply -var-file dev.tfvars

Production Setup

terraform init -backend-config=config.prod.hcl

Create a prod workspace

terraform workspace new prod

Plan Terraform

terraform plan -var-file prod.tfvars

Apply Terraform

terraform apply -var-file prod.tfvars  

Cleanup

Destroy Terraform

terraform destroy -var-file dev.tfvars  

Note:
  The emails will need to confirm subscription to SNS, in order to continue to receive billing alarms.
  An email will be sent from AWS to the emails
  The services mentioned in cost_filter have to be accurate; otherwise, budgeted data doesn’t get generated.

  cost_filter = {
      Service = ["Amazon Elastic Compute Cloud - Compute"]
    }

Requirements

Name	Version
terraform	~> 1.5
aws	~> 5.0

Providers

Name	Version
aws	5.46.0

Modules

Name	Source	Version
budgets	cloudposse/budgets/aws	0.4.0
this	cloudposse/label/null	0.25.0

Resources

Name	Type
aws_sns_topic_subscription.this	resource

Inputs

Name	Description	Type	Default	Required
additional_tag_map	Additional key-value pairs to add to each map in tags_as_list_of_maps. Not added to tags or id. This is for some rare cases where resources want additional configuration of tags and therefore take a list of maps with tag key, value, and additional configuration.	map(string)	{}	no
attributes	ID element. Additional attributes (e.g. workers or cluster) to add to id, in the order they appear in the list. New attributes are appended to the end of the list. The elements of the list are joined by the delimiter and treated as a single ID element.	list(string)	[]	no
billing_alerts_sns_subscribers	A map of subscription configurations for SNS topics For more information, see: https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/sns_topic_subscription#argument-reference protocol: The protocol to use. The possible values for this are: sqs, sms, lambda, application. (http or https are partially supported, see link) (email is an option but is unsupported in terraform, see link). endpoint: The endpoint to send data to, the contents will vary with the protocol. (see link for more information) endpoint_auto_confirms: Boolean indicating whether the end point is capable of auto confirming subscription e.g., PagerDuty. Default is false raw_message_delivery: Boolean indicating whether or not to enable raw message delivery (the original message is directly passed, not wrapped in JSON with the original message in the message property). Default is false	map(object({ protocol = string endpoint = string endpoint_auto_confirms = bool raw_message_delivery = bool }))	null	no
budgets	A list of Budgets to create.	any	[]	no
budgets_kms_master_key	KMS CMK to be used for encryption	string	null	no
context	Single object for setting entire context at once. See description of individual variables for details. Leave string and numeric variables as null to use default value. Individual variable settings (non-null) override settings in context object, except for attributes, tags, and additional_tag_map, which are merged.	any	{ "additional_tag_map": {}, "attributes": [], "delimiter": null, "descriptor_formats": {}, "enabled": true, "environment": null, "id_length_limit": null, "label_key_case": null, "label_order": [], "label_value_case": null, "labels_as_tags": [], "name": null, "namespace": null, "regex_replace_chars": null, "stage": null, "tags": {}, "tenant": null }	no
delimiter	Delimiter to be used between ID elements. Defaults to - (hyphen). Set to "" to use no delimiter at all.	string	null	no
descriptor_formats	Describe additional descriptors to be output in the descriptors output map. Map of maps. Keys are names of descriptors. Values are maps of the form {<br> format = string<br> labels = list(string)<br>} (Type is any so the map values can later be enhanced to provide additional options.) format is a Terraform format string to be passed to the format() function. labels is a list of labels, in order, to pass to format() function. Label values will be normalized before being passed to format() so they will be identical to how they appear in id. Default is {} (descriptors output will be empty).	any	{}	no
enabled	Set to false to prevent the module from creating any resources	bool	null	no
encryption_enabled	Whether or not to use encryption. If set to true and no custom value for KMS key (kms_master_key_id) is provided, a KMS key is created.	bool	true	no
environment	ID element. Usually used for region e.g. 'uw2', 'us-west-2', OR role 'prod', 'staging', 'dev', 'UAT'	string	null	no
id_length_limit	Limit id to this many characters (minimum 6). Set to 0 for unlimited length. Set to null for keep the existing setting, which defaults to 0. Does not affect id_full.	number	null	no
label_key_case	Controls the letter case of the tags keys (label names) for tags generated by this module. Does not affect keys of tags passed in via the tags input. Possible values: lower, title, upper. Default value: title.	string	null	no
label_order	The order in which the labels (ID elements) appear in the id. Defaults to ["namespace", "environment", "stage", "name", "attributes"]. You can omit any of the 6 labels ("tenant" is the 6th), but at least one must be present.	list(string)	null	no
label_value_case	Controls the letter case of ID elements (labels) as included in id, set as tag values, and output by this module individually. Does not affect values of tags passed in via the tags input. Possible values: lower, title, upper and none (no transformation). Set this to title and set delimiter to "" to yield Pascal Case IDs. Default value: lower.	string	null	no
labels_as_tags	Set of labels (ID elements) to include as tags in the tags output. Default is to include all labels. Tags with empty values will not be included in the tags output. Set to [] to suppress all generated tags. Notes: The value of the name tag, if included, will be the id, not the name. Unlike other null-label inputs, the initial setting of labels_as_tags cannot be changed in later chained modules. Attempts to change it will be silently ignored.	set(string)	[ "default" ]	no
name	ID element. Usually the component or solution name, e.g. 'app' or 'jenkins'. This is the only ID element not also included as a tag. The "name" tag is set to the full id string. There is no tag with the value of the name input.	string	null	no
namespace	ID element. Usually an abbreviation of your organization name, e.g. 'eg' or 'cp', to help ensure generated IDs are globally unique	string	null	no
regex_replace_chars	Terraform regular expression (regex) string. Characters matching the regex will be removed from the ID elements. If not set, "/[^a-zA-Z0-9-]/" is used to remove all characters other than hyphens, letters and digits.	string	null	no
slack_channel	The name of the channel in Slack for notifications. Only used when notifications_enabled is true	string	""	no
slack_notifications_enabled	Whether or not to setup Slack notifications. Set to true to create an SNS topic and Lambda function to send alerts to Slack.	bool	false	no
slack_username	The username that will appear on Slack messages. Only used when notifications_enabled is true	string	""	no
slack_webhook_url	The URL of Slack webhook. Only used when notifications_enabled is true	string	""	no
sns_topic_arn	SNS topic arn, if slack notificaiton is disabled	string	null	no
stage	ID element. Usually used to indicate role, e.g. 'prod', 'staging', 'source', 'build', 'test', 'deploy', 'release'	string	null	no
tags	Additional tags (e.g. {'BusinessUnit': 'XYZ'}). Neither the tag keys nor the tag values will be modified by this module.	map(string)	{}	no
tenant	ID element _(Rarely used, not included by default)_. A customer identifier, indicating who this instance of a resource is for	string	null	no

Outputs

Name	Description
budgets	List of Budgets that are being managed by this module
kms_key_arn	ARN of the KMS CMK that was created specifically for budget notifications
kms_key_id	ID of the KMS CMK that is used for SNS alerts
lambda_cloudwatch_log_group_arn	The ARN of the Log Group used by the Slack Notify Lambda
lambda_function_arn	The ARN of the Lambda function
lambda_function_invoke_arn	The ARN to be used for invoking lambda function from API Gateway
lambda_function_name	The name of the Lambda function
lambda_iam_role_arn	The ARN of the IAM role used by Lambda function
sns_topic_arn	ARN of the SNS topic created/used for alerts
sns_topic_name	The name of the SNS topic created for notifications

Git commits

while Contributing or doing git commit please specify the breaking change in your commit message whether its major,minor or patch

For Example

git commit -m "your commit message #major"

By specifying this , it will bump the version and if you dont specify this in your commit message then by default it will consider patch and will bump that accordingly

Development

Prerequisites

• terraform
• terraform-docs
• pre-commit
• golang
• golint

Configurations

• Configure pre-commit hooks

  pre-commit install
  

Tests

• Tests are available in test directory
• Configure the dependencies

  cd test/
  go mod init github.com/sourcefuse/terraform-aws-refarch-<module_name>
  go get github.com/gruntwork-io/terratest/modules/terraform
  

• Now execute the test
  

  go test -timeout  30m
  

Authors

This project is authored by: - SourceFuse