Data source dependencies in Terraform - Mini Project: Build & Apply

Data source dependencies in Terraform

📖 Scenario: You are setting up infrastructure using Terraform. You want to create a virtual machine that depends on the network information retrieved from a data source. This ensures the VM uses the correct network ID.

🎯 Goal: Build a Terraform configuration that uses a data source to get network details and then creates a virtual machine resource that depends on this data source.

📋 What You'll Learn

Create a data source block to fetch network information

Define a variable for the network name

Create a virtual machine resource that uses the network ID from the data source

Ensure the VM resource depends on the data source

💡 Why This Matters

🌍 Real World

In real cloud projects, resources often depend on existing infrastructure. Using data sources and dependencies ensures correct order and configuration.

💼 Career

Understanding data source dependencies is essential for cloud engineers and DevOps professionals managing infrastructure as code.

1

Create a data source to fetch network information

Write a Terraform data block named network using the provider azurerm_network_interface. Set the name attribute to "my-nic" and the resource_group_name attribute to "my-resource-group".

Terraform

# Your code here

Need a hint?

Use a data block with the exact name network and provider azurerm_network_interface.

2

Define a variable for the network name

Create a Terraform variable named network_name with a default value of "my-nic".

Terraform

data "azurerm_network_interface" "network" {
  name                = "my-nic"
  resource_group_name = "my-resource-group"
}

# Your code here

Need a hint?

Use a variable block with the exact name network_name and set its default to "my-nic". Update the data source to use var.network_name for the name.

3

Create a virtual machine resource using the network ID

Add a Terraform resource block named azurerm_linux_virtual_machine with the resource name vm. Set the name to "my-vm", resource_group_name to "my-resource-group", location to data.azurerm_network_interface.network.location, and network_interface_ids to a list containing data.azurerm_network_interface.network.id.

Terraform

data "azurerm_network_interface" "network" {
  name                = var.network_name
  resource_group_name = "my-resource-group"
}

variable "network_name" {
  default = "my-nic"
}

# Your code here

Need a hint?

Use a resource block with the exact name azurerm_linux_virtual_machine and resource name vm. Use the network ID from the data source in network_interface_ids.

4

Add explicit dependency on the data source

Add the depends_on attribute to the azurerm_linux_virtual_machine.vm resource. Set it to a list containing data.azurerm_network_interface.network to ensure the VM depends on the network data source.

Terraform

data "azurerm_network_interface" "network" {
  name                = var.network_name
  resource_group_name = "my-resource-group"
}

variable "network_name" {
  default = "my-nic"
}

resource "azurerm_linux_virtual_machine" "vm" {
  name                = "my-vm"
  resource_group_name = "my-resource-group"
  location            = data.azurerm_network_interface.network.location
  network_interface_ids = [data.azurerm_network_interface.network.id]
  size                = "Standard_DS1_v2"
  admin_username      = "adminuser"
  admin_password      = "Password1234!"
  os_disk {
    caching              = "ReadWrite"
    storage_account_type = "Standard_LRS"
  }
  source_image_reference {
    publisher = "Canonical"
    offer     = "UbuntuServer"
    sku       = "18.04-LTS"
    version   = "latest"
  }
  # Your code here
}

Need a hint?

Add the depends_on attribute inside the VM resource block with the exact value [data.azurerm_network_interface.network].