Build a Local Terraform Module

Step-01: Introduction¶

We will build a Terraform local module to host a static website on Azure Storage Account.
We will understand how to call a Local Re-usable module in to a Root Module.
We will understand how the local module variables becomes the arguments inside a module block when it is called in Root Module c3-static-webiste.tf
We will understand how we define the output values for a local module in a Root module c4-outputs.tf
Terraform Comamnd terraform get
Understand the differences between terraform init and terraform get

Step-02: Create Module Folder Structure¶

We are going to create modules folder and in that we are going to create a module named azure-static-website
We will copy required files from previous section for this respective module 50-Terraform-Azure-Static-Website\terraform-manifests.
Terraform Working Directory: 51-Terraform-Modules-Build-Local-Module\terraform-manifests
modules
Module-1: azure-static-website
main.tf
variables.tf
outputs.tf
README.md
LICENSE
Inside modules/azure-static-website, copy below listed three files from 50-Terraform-Azure-Static-Website\terraform-manifests
main.tf
variables.tf
outputs.tf
versions.tf

Step-03: Root Module: c1-versions.tf¶

Call Module from Terraform Work Directory
Create Terraform Configuration in Root Module by calling the newly created module
c1-versions.tf
c2-variables.tf
c3-static-website.tf

c4-outputs.tf

# Terraform Block
terraform {
  required_version = ">= 1.0.0"
  required_providers {
    azurerm = {
      source = "hashicorp/azurerm"
      version = ">= 2.0" 
    }    
  }
}

# Provider Block
provider "azurerm" {
 features {}          
}

Step-04: c2-variables.tf¶

Place holder file, if you want you can define variables.
For now focus is on Calling the Local Terraform Module in to Root Module so we are not going to complicate the stuff here.
We will leave this placeholder file

Step-05: c3-static-website.tf¶

Arguments for this module are going to be the variables defined in variables.tf of local module

# Call our Custom Terraform Module which we built earlier
module "azure_static_website" {
  source = "./modules/azure-static-website"  # Mandatory

  # Resource Group
  location = "eastus"
  resource_group_name = "myrg1"

  # Storage Account
  storage_account_name = "staticwebsite"
  storage_account_tier = "Standard"
  storage_account_replication_type = "LRS"
  storage_account_kind = "StorageV2"
  static_website_index_document = "index.html"
  static_website_error_404_document = "error.html"
}

Step-06: c4-outputs.tf¶

Understand how we are going to reference the output values from a local module

The output names defined in local module outputs.tf will be the values in this c4-outputs.tf

# Output variable definitions
output "root_resource_group_id" {
  description = "resource group id"
  value       = module.azure_static_website.resource_group_id
}
output "root_resource_group_name" {
  description = "The name of the resource group"
  value       = module.azure_static_website.resource_group_name
}
output "root_resource_group_location" {
  description = "resource group location"
  value       = module.azure_static_website.resource_group_location
}
output "root_storage_account_id" {
  description = "storage account id"
  value       = module.azure_static_website.storage_account_id
}
output "root_storage_account_name" {
  description = "storage account name"
  value       = module.azure_static_website.storage_account_name
}

Step-07: Execute Terraform Commands¶

# Terraform Initialize
terraform init
Observation: 
1. Verify ".terraform", you will find "modules" folder in addition to "providers" folder
2. Verify inside ".terraform/modules" folder too.

# Terraform Validate
terraform validate

# Terraform Format
terraform fmt

# Terraform Plan
terraform plan

# Terraform Apply
terraform apply -auto-approve

# Upload Static Content
1. Go to Storage Accounts -> staticwebsitexxxxxx -> Containers -> $web
2. Upload files from folder "static-content"

# Verify 
1. Azure Storage Account created
2. Static Website Setting enabled
3. Verify the Static Content Upload Successful
4. Access Static Website: Goto Storage Account -> staticwebsitek123 -> Data Management -> Static Website
5. Get the endpoint name `Primary endpoint`
https://staticwebsitek123.z13.web.core.windows.net/

Step-08: Destroy and Clean-Up¶

# Terraform Destroy
terraform destroy -auto-approve

# Delete Terraform files 
rm -rf .terraform*
rm -rf terraform.tfstate*

Step-09: Understand terraform get command¶

We have used terraform init to download providers from terraform registry and at the same time to download modules present in local modules folder in terraform working directory.
Assuming we already have initialized using terraform init and later we have created module configs, we can terraform get to download the same.
Whenever you add a new module to a configuration, Terraform must install the module before it can be used.
Both the terraform get and terraform init commands will install and update modules.

The terraform init command will also initialize backends and install plugins.

# Delete modules in .terraform folder
ls -lrt .terraform/modules
rm -rf .terraform/modules
ls -lrt .terraform/modules

# Terraform Get
terraform get
ls -lrt .terraform/modules

Step10: Major difference between Local and Remote Module¶

When installing a remote module, Terraform will download it into the .terraform directory in your configuration's root directory.
When installing a local module, Terraform will instead refer directly to the source directory.
Because of this, Terraform will automatically notice changes to local modules without having to re-run terraform init or terraform get.