title	description
Terraform Settings, Providers and Resource Blocks	Learn Key blocks of Terraform like Settings, Providers and Resource Blocks

Step-01: Introduction

Terraform Block

• Understand about Terraform Block and its importance
• Understand how to handle version constraints for Terraform Version and Provider Version in Terraform Block

Provider Block

• What are Terraform Providers?
• What Providers Do?
• Where do providers reside (Terraform Registry)?
• How to use Providers?
• What are Provider Badges?

Step-02: Understand about Terraform Settings Block

• Terraform Settings Block
• Required Terraform Version
• Provider Requirements
• Terraform backends
• Experimental Language Features
• Passing Metadata to Providers
• Reference sample-terraform-settings.tf for additional understanding.

Step-03: Create a simple terraform block and play with required_version

• required_version focuses on underlying Terraform CLI installed on your desktop
• If the running version of Terraform on your local desktop doesn't match the constraints specified in your terraform block, Terraform will produce an error and exit without taking any further actions.
• By changing the versions try terraform init and observe whats happening

# Play with Terraform CLI Version (We installed 1.0.0 version)
  required_version = "~> 0.14.3" - Will fail
  required_version = "~> 0.14"   - Will fail  
  required_version = "= 0.14.4"  - Will fail
  required_version = ">= 0.13"   - will pass
  required_version = "= 1.0.0"   - will pass
  required_version = "1.0.0"     - will pass 
  required_version = ">= 1.0.0"   - will pass   
 
# Terraform Block
terraform {
  required_version = ">= 1.0.0"
}

# To view my Terraform CLI Version installed on my desktop
terraform version

# Initialize Terraform
terraform init

Step-04: Terraform Providers

• What are Terraform Providers?
• What Providers Do?
• Where do providers reside (Terraform Registry)?

Step-05: Provider Requirements

• Define required providers in Terraform Block
• Understand about three things about defining required_providers in terraform block
  • local names
  • source
  • version

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

Step-06: Provider Block

• Create a Provider Block for Azure Resource Management azurerm

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

• Discuss about Authentication Types
• Authenticating to Azure using the Azure CLI
• Authenticating to Azure using Managed Service Identity
• Authenticating to Azure using a Service Principal and a Client Certificate
• Authenticating to Azure using a Service Principal and a Client Secret
• Finally, understand about Features Block in Provider Block

# Initialize Terraform
terraform init

# Validate Terraform Configuration files
terraform validate

# Execute Terraform Plan
terraform plan

Step-07: Add Provider and play with Provider version

• required_providers block specifies all of the providers required by the current module, mapping each local provider name to a source address and a version constraint.

# Play with Provider Version
      version = "~> 2.0"            
      version = ">= 2.0.0, < 2.60.0"
      version = ">= 2.0.0, <= 2.64.0"

# Terraform Init with upgrade option to change provider version
terraform init -upgrade

Step-08: Create a simple Resource Block - c2-resource-group.tf

# Resource Block
# Create a resource group
resource "azurerm_resource_group" "myrg" {
  name = "myrg-1"
  location = "East US"
}

Step-09: Execute Terraform commands

# Initialize Terraform
terraform init

# Validate Terraform Configuration files
terraform validate

# Execute Terraform Plan
terraform plan

# Create Resources using Terraform Apply
terraform apply -auto-approve

Step-10: Clean-Up

# Destroy Terraform Resources
terraform destroy -auto-approve

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

References

• Terraform Providers
• Azure Provider Documentation
• Azure Resource Group Terraform Resource
• Terraform Version Constraints
• Terraform Versions - Best Practices