Terraform Override Files

Step-01: Introduction

• Terraform Override Files
• Understand and Implement about Override File Formats
• override.tf
• somefilename_override.tf

Step-02: Review Terraform Configs in terraform-manifests-v1

• c1-versions.tf
• c2-variables.tf
• c3-resource-group.tf
• c4-virtual-network.tf
• terraform.tfvars

Step-03: terraform-manifests-v1 - override.tf

• Define the same Resource Group resource with different location

# Resource-1: Azure Resource Group
resource "azurerm_resource_group" "myrg" {
  #name = var.resource_group_name
  name = "${var.business_unit}-${var.environment}-${var.resoure_group_name}"
  location = "westus"
}

Step-04: terraform-manifests-v1 - Execute Terraform Commands

# Change Directory
cd terraform-manifests-v1/

# Terraform Initialize
terraform init

# Terraform Validate
terraform validate

# Terraform Plan
terraform plan

# Observation
1. Review the location for all resources.
2. Location of all resources should be "westus" because it has picked the information from "override.tf"

# Clean-Up
rm -rf .terraform*

Step-05: terraform-manifests-v2 - c3-resource-group_override.tf

# Resource-1: Azure Resource Group
resource "azurerm_resource_group" "myrg" {
  #name = var.resource_group_name
  name = "${var.business_unit}-${var.environment}-${var.resoure_group_name}"
  location = "westus"
}

Step-06: terraform-manifests-v2 - Execute Terraform Commands

# Change Directory
cd terraform-manifests-v2/

# Terraform Initialize
terraform init

# Terraform Validate
terraform validate

# Terraform Plan
terraform plan

# Observation
1. Review the location for all resources.
2. Location of all resources should be "westus" because it has picked the information from "c3-resource-group_override.tf"

# Clean-Up
rm -rf .terraform*

Step-07: Discuss about .gitignore Terraform - Default behavior

• By default if we use .gitignore of Terraform from github it will have override files ignored.
• Based on need, you need to comment them in .gitignore if those are required and our .tf files are checked-in to github.

# Ignore override files as they are usually used to override resources locally and so
# are not checked in
#override.tf
#override.tf.json
#*_override.tf
#*_override.tf.json