Terraform context module

Terraform module for generating consistent names and tags.

This module is not tied to any specific cloud provider but has generally been used with Amazon Web Services to generate unique names and billing tags for infrastructure resources.

Getting started

Requirements

• Terraform 1.4

Installation and usage

Add the following Terraform to your stack:

module "context" {
  source  = "registry.terraform.io/unfunco/context/null"
  version = "0.3.0"

  organization = var.context.organization
  application  = var.context.application
  account      = var.context.account
  environment  = var.context.environment
  stack        = var.context.stack
}

variable "context" {
  description = "Single object for setting the entire context."

  type = object({
    organization = optional(string)
    application  = string
    account      = string
    environment  = optional(string)
    stack        = string
  })
}

When using Terragrunt, you can use a generate block to create the context.

generate "context" {
  contents = <<EOF
module "context" { ... }
variable "context" { ... }
EOF

  if_exists = "overwrite"
  path      = "context.tf"
}

The outputs from the context module can be used to uniquely name and tag your infrastructure resources.

resource "aws_s3_bucket" "assets" {
  bucket = module.context.id
  tags   = merge(module.context.tags, var.tags)
}

resource "aws_ssm_parameter" "api_token" {
  name  = join("/", [module.context.path, "API-TOKEN"])
  tags  = merge(module.context.tags, var.tags)
  type  = "SecureString"
  value = "CorrectHorseBatteryStaple"
}

Automate the composition of CLI commands and pass in the context as JSON, an apply command might look something like this:

TF_WORKSPACE=hyperglug_live_assets terraform apply \
  -lock="true" \
  -lock-timeout="1m" \
  -var='context={"organization":"honestempire","application":"hyperglug","account":"live","environment":"live","stack":"assets"}' \
  -var-file="assets.tfvars.json"

With the examples above, the following names and tags are generated:

bucket_id = "hyperglug-live-assets"

bucket_tags = tomap({
  "Account"      = "live"
  "Application"  = "hyperglug"
  "Organization" = "honestempire"
  "Stack"        = "assets"
  "Environment"  = "live"
})

ssm_parameter_name = "/hyperglug/live/assets/API-TOKEN"

Inputs

Name	Description	Type	Default	Required
account	The name of the account.	string	n/a	yes
application	The name of the application.	string	n/a	yes
environment	The name of the environment.	string	n/a	yes
organization	The name of the organization.	string	n/a	yes
stack	The name of the stack.	string	n/a	yes

Variables

Name	Default	Description
organization	null	The name of the organization.
application	null	The name of the application.
account	null	The name of the account.
environment	null	The name of the environment.
order	["application", "account", "environment", "stack"]	Labels in the order they should be applied.
stack	null	The name of the stack.

Outputs

The outputs have been separated into two tables, the first table contains the outputs that are most likely to be provided as inputs to other resources. The ID output is a hyphenated concatenation of the application, account, environment and stack inputs, and can be used for resource names, the path is slash-delimited, and can be used for SSM parameter prefixes, for example.

Name	Description
id	The disambiguated ID of the module.
path	The disambiguated ID delimited with slashes.
tags	The normalised map of tags.

The next table contains the outputs that are really just normalised versions of the input variables.

Name	Description
organization	The normalised name of the organization.
application	The normalised name of the application.
account	The normalised name of the account.
environment	The normalised name of the environment.
stack	The normalised name of the stack.

License

© 2021 Daniel Morris
Made available under the terms of the Apache License 2.0.