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Understand Terraform Language Basics

Step-01: Introduction

  • Understand Terraform language basics
  • Understand Resources
  • Understand Blocks
  • Understand Arguments
  • Understand Identifiers
  • Understand Comments
  • Understand Input Variables in Terraform
  • Understand Output Values in Terraform
  • Migrate Terraform State from local to Remote Storage (Azure Storage)

Azure Kubernetes Service with Azure DevOps and Terraform

Step-02: Terraform Configuration Language Syntax

  • Understand Resources
  • Understand Blocks
  • Understand Arguments
  • Understand Identifiers
  • Understand Comments
  • Terraform Configuration
  • Terraform Configuration Syntax
    # Template
      # Block body
      <IDENTIFIER> = <EXPRESSION> # Argument
    # Example
    resource "azurerm_resource_group" "aksdev" {   # BLOCK
      name     = "aks-rg2-tf" # Argument
      location = var.region   # Argument with value as expression (Variable value replaced from )
      tags = {  #BLOCK
        "environment" = "k8sdev"

Step-03: Define Terraform Providers

  • VS Code Terraform Plugin - Syntax highlighting and autocompletion for Terraform
  • Understand about Terraform Settings Block
  • We primarily define the below 3 items in Terraform Settings Block
  • Terraform Version
  • Terraform Providers
  • Terraform State Storage Backend
  • Create a file and create terraform providers
    # Terraform Settings Block (
    terraform {
      # Use a recent version of Terraform
      required_version = ">= 0.13"
      # Map providers to thier sources, required in Terraform 13+
      required_providers {
        # Azure Resource Manager 2.x (Base Azure RM Module)
        azurerm = {
          source  = "hashicorp/azurerm"
          version = "~> 2.0"
        # Azure Active Directory 1.x (required for AKS and Azure AD Integration)
        azuread = {
          source  = "hashicorp/azuread"
          version = "~> 1.0"
        # Random 3.x (Required to generate random names for Log Analytics Workspace)
        random = {
          source  = "hashicorp/random"
          version = "~> 3.0"
    # Configure Terraform State Storage
        backend "azurerm" {
        resource_group_name   = "terraform-storage-rg"
        storage_account_name  = "terraformstatexlrwdrzs"
        container_name        = "prodtfstate"
        key                   = "terraform.tfstate"

Step-04: Define Azure Resource Manager Features Block

  • Add azurerm features block to
    # This block is required for azurerm 2.x
    provider azurerm {
      # v2.x azurerm requires "features" block
      features {}

Step-05: Create Random Pet Resource

  • Create Random pet resource in
    # Create Random pet resource
    resource "random_pet" "aksrandom" {}
  • Initialize the terraform and understand what happened
    # Terraform Initialize
    terraform init

Step-06: Create a Resource Group Resource

  • Create a file named
    resource "azurerm_resource_group" "aks_rg" {
      location = "Central US"
      name     = "terraform-aks"

Step-07: Understand and Create Terraform Input Variables

Three types of Terraform Variables

Input Variables

  • We can parameterize our deployments using Terraform Input Variables.
  • This is the right way to build a Terraform project that can be reused to deploy multiple environments like dev, qa, staging and production
  • Implement input variables in terraform for AKS Cluster
  • Understand different options available to pass input variables
  • arguments during runtime (-var)
  • arguments during runtime (-var-file terraform.tfvars) with a file containing variables


  • Define few input variables in
  • Reference them in
  • Variables we are going to play with
  • Resource Group Name
  • Location or Region
  • AKS Environment Name

Create Variables in a file and Reference them

  • Create a variables file
    # Input Variables
    # Output Values
    # Local Values
    # Define Input Variables
    # 1. Azure Location (CentralUS)
    # 2. Azure Resource Group Name 
    # 3. Azure AKS Environment Name (Dev, QA, Prod)
    # 4. Azure AKS Cluster Name
    # Azure Location
    variable "location" {
      type = string
      description = "Azure Region where all these resources will be provisioned"
      default = "Central US"
    # Azure Resource Group Name
    variable "resource_group_name" {
      type = string
      description = "This variable defines the Resource Group"
      default = "terraform-aks"
    # Azure AKS Environment Name
    variable "environment" {
      type = string  
      description = "This variable defines the Environment"  
      default = "prod"
  • Update a file named with Variable references
    # Terraform Resource to Create Azure Resource Group with Input Variables defined in
    resource "azurerm_resource_group" "aks_rg" {
      location = var.location
      name     = var.resource_group_name

Step-08: Terraform Input Variables - Multiple Options

Option-1: With -var

  • -var flag enables a single input variable value to be passed in at the command-line per each -var.
    # Execute Terraform plan with -var and observe
    terraform plan -var "location=eastus"
    Observation: Value to should be picked from runtime -var what ever provided which is eastus.

Option-2: With -var-file

  • -var-file flag enables multiple input variable values to be passed in by referencing a file that contains the values.
  • Create file terraform.tfvars
    terraform.tfvars with content in it as 
    location = "westus"
    # Run plan and observe 
    terraform plan 
    Observation: No need to give -var-file when name terraform.tfvars and values pickup directly from terraform.tfvars
  • Rename file name terraform.tfvars to dev.tfvars
    # Run plan and observe 
    terraform plan 
    Observation: dev.tfvars will not be picked and value comes from default attribute
    # Run plan with -var-file 'dev.tfvars'
    terraform plan -var-file 'dev.tfvars'
    Observation: value to should be picked from dev.tfvars now

Option-3: With

  • We already seen the auto loading of .tfvars when the file name is terraform.tfvars
  • Now we can also do that when we have the file names with
  • Lets try out

    # Rename file 
    mv dev.tfvars
    # Execute Terraform plan (No runtime arguments like -var-file)
    terraform plan
    Observation: You can see that variable present in autoloaded now. 

  • Clean-Up: Move to backup folder for reference and move back to original and move to next step.

Option-4: With Environment Variables

  • When running Terraform commands, we can also use Environment Variables to define the values for Input Variables
  • Important Note: Be sure to keep in mind that if the Operating System is case-sensitive, then Terraform will match variable names exactly as given during configuration.
    # Template
    TF_VAR_<VARIABLE-NAME>  - case-sensitive
    # Set Environment Variable using Bash
    export TF_VAR_location="westus"

Step-09: Final Look of Resource Group

  • Combine Two variables to make it one for resource group
  • Two have 1 resource group per environment (dev, qa), we are going to use this approach
    resource "azurerm_resource_group" "aks_rg" {
      location = var.location
      name     = "${var.resource_group_name}-${var.environment}"

Step-10: Define Output Values

  • Understand about Terraform Output Values
  • Output values are like the return values of a Terraform module
  • Output values are a way to expose some of that information to the user of your module.
  • A child module can use outputs to expose a subset of its resource attributes to a parent module
  • A root module can use outputs to print certain values in the CLI output after running terraform apply
    # Create Outputs
    # 1. Resource Group Location
    # 2. Resource Group Id
    # 3. Resource Group Name
    output "location" {
      value = azurerm_resource_group.aks_rg.location
    output "resource_group_id" {
      value =
    output "resource_group_name" {
      value =

Step-11: Create or Deploy Terraform Resources & Verify

# Initialize Terraform 
terraform init

# Validate Terraform Templates
terraform validate

# Execute Terraform Plan
terraform plan
terraform plan -out v1out.plan

# Create / Deploy Terraform Resources
terrafrom apply 
terraform apply v1out.plan 

# Verify current infrastructure state
terraform show

# Format Terraform files
terraform fmt

Step-12: Verify the same in Azure Portal Mgmt Console

  • Verify if Resource Group got created in Azure Mgmt Console
  • Understand about terraform state file named terraform.tfstate
  • Migrate this state file to Azure Storage Account

Step-13: Migrate Terraform State Storage to Azure Storage Account

Create Azure Storage Account in new Resource Group

  • Why should be we create terraform state storage in different resource group?
  • State storage is key for all terraform resources and it should be deleted at any point of time even accidentally.
  • Create New Resource Group: terraform-storage-rg
  • Create Storage Account: terraformstatexlrwdrzs (Note: Name should be unique across Azure)
  • Create Container Name: tfstatefiles
  • Upload the file terraform.tfstate to storage account container

Update with Terraform State Storage

# Configure Terraform State Storage
terraform {
  backend "azurerm" {
    resource_group_name   = "terraform-storage-rg"
    storage_account_name  = "terraformstatexlrwdrzs"
    container_name        = "tfstatefiles"
    key                   = "terraform.tfstate"

Migrate terraform backend by re-initializing

  • First backup local terraform.tfstate
    # Backup existing terraform.tfstate present locally
    mv terraform.tfstate BACKUP-LOCAL-TFSTATE
    # Try terraform validate
    terraform validate
    # Try terraform plan (Should fail telling us to re-initialize backed)
    terraform plan
    # Re-Initialize Terraform Backend
    terraform init 
    # Verify if any local state file
    ls -lrta
  • This completes successful migration of terraform.tfstate from local to Azure Storage Container
  • No local dependency now. Straight away initialize your terraform files from any folder and start working


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