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06-Applying Modules in Terraform.md

Learning Goals

This exercise provides an opportunity to use Terraform modules by creating a scalable and repeatable infrastructure with virtual machines (VMs) in Azure.

Modules are a good way to encapsulating configurations of related resources into reusable, shareable units. Both teams internal in a company, as well as providers can create them.

In this exercise, we are going to use the module virtual-machine to simplify creating a virtual machine in Azure.

This module defines 8 resources.

  • azurerm_linux_virtual_machine.vm_linux
  • azurerm_managed_disk.disk
  • azurerm_network_interface.vm
  • azurerm_storage_account.boot_diagnostics
  • azurerm_virtual_machine_data_disk_attachment.attachment
  • azurerm_virtual_machine_extension.extensions
  • azurerm_windows_virtual_machine.vm_windows
  • random_id.vm_sa

exercise6(1)

Objectives

  • Understand the use of Terraform modules for resource deployment.
  • Learn to interpret and apply configurations from YAML files.
  • Deploy three virtual machines using the for_each construct to loop over configurations.
  • Clean up resources to prevent unnecessary Azure charges.

Step-by-Step Instructions

  • Go to the folder labs/06-Applying-Modules-in-Terraform/start. That is where your exercise files should be created.

Define Variables in variables.tf

Before diving into the actual Terraform configurations, we start by defining the variables in thevariables.tf file to our project like last exercise.

Task Instructions:

  1. Navigate to the variables.tf file:

    • Navigate to labs/06-Applying-Modules-in-Terraform/start.
    • A file called variables.tfshould already be created.

  2. Define the following variables:

    • exercise: A string variable used to make the name of some of the resources unique.

    • instances_configuration: A string variable pointing to a YAML file structured with VM configurations.

      variable "instances_configuration" {
  type        = string
  description = <<EOT
        "Should point to a yaml file, structured as:"
        data:
            VMNAME:
                size: "VM SKU"
                public_ip: true/false
                subnet: client
            client2:
                size: "VM SKU"
                public_ip: true
                subnet: client
            server:
                size: "VM SKU"
                public_ip: false
                subnet: server
        EOT
}

    • network_configuration: A string variable pointing to a YAML file structured with network configurations.

      variable "network_configuration" {
  type        = string
  description = <<EOT
        "Should point to a yaml file, structured as:"
            data:
            ranges:
            - 10.0.0.0/16
            subnets:
                client:
                    ranges:
                    - 10.0.0.0/24
                server:
                    ranges:
                    - 10.0.1.0/24
        EOT
}

    • admin_password: A sensitive string variable for the default password to connect to the servers.

      variable "admin_password" {
  type        = string
  sensitive   = true
  description = "default password to connect to the servers we deploy"
}

    • admin_username: A sensitive string variable for the default admin user to connect to the servers.

      variable "admin_username" {
  type        = string
  sensitive   = true
  description = "default admin user to connect to the servers we deploy"
}

Define Configuration Values in _config.auto.tfvars

Create a _config.auto.tfvars file to automatically provide values for your variables during Terraform runs.

Task Instructions:

  1. Create the _config.auto.tfvars file:

    • Navigate to labs/06-Applying-Modules-in-Terraform/start.
    • Create a new file named _config.auto.tfvars.

  2. Define the following values:

    • exercise: Assign a unique identifier for your exercise.
    • instances_configuration: Provide the relative path to your instances.yaml file.
    • network_configuration: Provide the relative path to your network.yaml file.
    • admin_username: Assign a value for the admin username.
    • admin_password: Assign a value for the admin password.
    exercise                = "exercise6"
instances_configuration = "configuration/instances.yaml"
network_configuration   = "configuration/network.yaml"
admin_password          = "aflk89!nknvlknglkvgew"
admin_username          = "adminuser"

Create YAML Configuration Files

  1. Create the instances.yaml file:

    • Navigate to labs/06-Applying-Modules-in-Terraform/start/configuration.
    • A file named instances.yaml should already be created there.

  2. Define the VM configurations in instances.yaml:

data:
  client1:
    size: "Standard_B1ls"
    public_ip: true
    subnet: client
  client2:
    size: "Standard_B1ls"
    public_ip: true
    subnet: client
  server:
    size: "Standard_B1ls"
    public_ip: false
    subnet: server

  1. Create the network.yaml file:

    • Navigate to labs/06-Applying-Modules-in-Terraform/start/configuration.
    • A file named network.yaml should already be created there.

  2. Define the VM configurations in network.yaml:

data:
  ranges: 
  - 10.0.0.0/16
  subnets:
    client: 
      ranges: 
      - 10.0.0.0/24
    server:
      ranges: 
      - 10.0.1.0/24

Checkpoint 1: Initialize and Plan After Defining Configurations

Once you've defined your variables in variables.tf, set your configuration values in _config.auto.tfvars, and created the YAML files, you can initialize and plan Terraform to ensure all configurations are correctly set up.

terraform init
terraform plan

Create Network Resources

Create a file 00_create_network.tf to set up the virtual network and associated subnets using data from network.yaml.

Task Instructions:

  1. Create the 00_create_network.tf file:

    • Navigate to the labs/06-Applying-Modules-in-Terraform/start directory.
    • A file named 00_create_network.tf should already be created there.

  2. Define Local Variables to Read YAML Data:

    • Inside the 00_create_network.tf file, define a locals block.
    • Use the file function to read the content of the network.yaml file. Reference the file path using the ${path.root}/${var.network_configuration} syntax.
    • Use the yamldecode function to convert the YAML file content into a data structure.
    • Store the decoded YAML data in a local variable named yaml_network_data.
    • Extract the data section from yaml_network_data and store it in another local variable named network.

  3. Create the Virtual Network:

    • Define a resource block for the azurerm_virtual_network resource.
    • Name the resource block main.
    • Set the name property to "vnet-${var.exercise}" to include the exercise number for uniqueness.
    • Set the resource_group_name property to data.azurerm_resource_group.studentrg.name.
    • Set the location property to data.azurerm_resource_group.studentrg.location.
    • Set the address_space property to the value of local.network.ranges.

  4. Create Subnets:

    • Define a resource block for the azurerm_subnet resource.
    • Name the resource block main.
    • Use the for_each expression to loop over the subnets defined in the network local variable.
    • Set the name property to the key of each subnet in the loop. Use each.key to reference the key.
    • Set the resource_group_name property to data.azurerm_resource_group.studentrg.name.
    • Set the virtual_network_name property to azurerm_virtual_network.main.name.
    • Set the address_prefixes property to the address ranges defined for each subnet. Use each.value.ranges to reference the ranges.

If you encounter any issues or need to verify your configurations, refer to the done folder in the same directory for the solution.

Checkpoint 2: Initialize, Plan, and Apply Network Resources

After defining the network and subnet resources, initialize Terraform again, plan the configuration, and apply it to create the network and subnets.

terraform init
terraform plan
terraform apply

Deploy Virtual Machines

Create a file 01_createinstances.tf to deploy VMs based on configurations specified in instances.yaml using a Terraform module for VM creation.

Task Instructions:

  1. Create the 01_createinstances.tf file:

    • Navigate to the labs/06-Applying-Modules-in-Terraform/start directory.
    • Create a new file named 01_createinstances.tf.

  2. Define Local Variables to Read YAML Data:

    • Inside the 01_createinstances.tf file, define a locals block.
    • Use the file function to read the content of the instances.yaml file.
    • Use the yamldecode function to convert the YAML file content into a data structure.
    • Store the decoded YAML data in a local variable named yaml_vms_data.
    • Extract the data section from yaml_vms_data and store it in another local variable named instances.

  3. Create Public IP Resources:

    • Define a resource block for the azurerm_public_ip resource.
    • Name the resource block pip.
    • Use the for_each expression to create public IPs for VMs that require them, based on the YAML configuration.
    • Set the name property to "${each.key}-public-ip" to create a unique name for each public IP.
    • Set the location property to data.azurerm_resource_group.studentrg.location.
    • Set the resource_group_name property to data.azurerm_resource_group.studentrg.name.
    • Set the allocation_method property to "Dynamic".
    • Add any necessary tags using the tags property.

  4. Use the Virtual Machine Module:

  • Define a module block to utilize the Azure/virtual-machine/azurerm module.
  • Use the for_each expression to loop over VM configurations.
  • Set the source parameter to "Azure/virtual-machine/azurerm".
  • Set the version parameter to "1.1.0".
  • Configure the module with the following parameters:
    • location: Set to data.azurerm_resource_group.studentrg.location.
    • resource_group_name: Set to data.azurerm_resource_group.studentrg.name.
    • image_os: Set to "linux".
    • allow_extension_operations: Set to false.
    • admin_username: Set to var.admin_username.
    • disable_password_authentication: Set to false.
    • admin_password: Set to var.admin_password.
    • name: Set to each.key.
    • os_simple: Set to "UbuntuServer".
    • size: Set to each.value.size.
    • subnet_id: Set to azurerm_subnet.main[each.value.subnet].id.
    • Add any necessary tags using the tags property.

  1. Define Network Interface Configuration:

    • Set the new_network_interface parameter within the module block.
    • Configure the new_network_interface with the following properties:
      • ip_forwarding_enabled: Set to false.
      • ip_configurations: Define an array with the following properties:
        • public_ip_address_id: Reference the public IP created by the azurerm_public_ip resource block.
        • primary: Set to true.

  2. Define OS Disk Configuration:

    • Set the os_disk parameter within the module block.
    • Configure the os_disk with the following properties:
      • caching: Set to ReadWrite.
      • storage_account_type: Set to Standard_LRS.

  3. Define Boot Diagnostics Configuration:

    • Set the new_boot_diagnostics_storage_account parameter within the module block.
    • Configure the new_boot_diagnostics_storage_account to an empty object.

If you encounter any issues or need to verify your configurations, refer to the done folder in the same directory for the solution.

Apply the Configuration

Task Instructions:

  1. Initialize Terraform:

    • Run terraform init to prepare the backend and install required providers.

  2. Plan the Deployment:

    • Run terraform plan to review the planned actions by Terraform.
    • Terraform will automatically use the values provided in _config.auto.tfvars file.

  3. Apply Terraform Configuration:

    • Run terraform apply.
    • Terraform will automatically use the values provided in _config.auto.tfvars file.

  4. Verify the Deployment:

    • Check the Azure portal to view the resources created in your resource group.

Verify and Clean Up

After deploying the resources, verify the VMs' functionality by accessing them as needed. Ensure they are operating within the correct network and accessible per your configuration

To manage costs effectively and avoid unnecessary charges in Azure:

  • Run terraform destroy to clean up all resources deployed during this exercise.

This command cleans up all resources deployed during this exercise.

Well done

You've successfully utilized Terraform modules to deploy and manage virtual machines in Azure.

This exercise demonstrates the power of Terraform in managing complex infrastructure setups efficiently and repeatably.