Infra Automation by Terraform Dynamic Block for List(Objects) Usecase — Part7

Dynamic blocks in Terraform are used when you want to generate multiple instances of a block within a resource or module dynamically. This is particularly useful when you have a variable number of similar configurations to define. One common use case for dynamic blocks is when you’re working with a list of items, and you want to generate a block for each item in the list.

Here’s a simple use case to illustrate the use of dynamic blocks:

Let’s say you have a list of security group rules, and you want to create Azure Security Group rules using Terraform. The rules are defined by a list of objects, where each object contains the details of a rule.

Azure Security Group with Dynamic Block

// main.tf 

resource "azurerm_resource_group" "example" {
  name     = "example-resources1"
  location = "West Europe"
}

provider "azurerm" {
  features {}
    subscription_id = "491e1121-c626-4***"
    tenant_id = "2047b1bd-994d-4366-9d343****"
    client_id = "a78d2362-7c1d-475b634019705***"
    client_secret = "aSR8Q~UzW_2fWfpMnAHLnY~04qdEl~****"
  
}


resource "azurerm_network_security_group" "example" {
  name                = "acceptanceTestSecurityGroup1"
  location            = azurerm_resource_group.example.location
  resource_group_name = azurerm_resource_group.example.name

  dynamic "security_rule"{
    for_each = var.virtual_network_rules
    content {
    name                       = security_rule.value["name"]
    priority                   = security_rule.value["priority"]
    direction                  = "Inbound"
    access                     = "Allow"
    protocol                   = "Tcp"
    source_port_range          = "*"
    destination_port_range     = "*"
    source_address_prefix      = "*"
    destination_address_prefix = "*"
    }
  }


  tags = {
    environment = "Production"
  }
}

//Variables.tf 

variable "virtual_network_rules" {
  type = list(object({
    name              = string
    priority          = number
  }))
}

//dev.tfvars 

virtual_network_rules = [
  {
    name     = "rule-1"
    priority = 101
  },
  {
    name     = "rule-1"
    priority = 101
}]

Commands to execute the Terraform modules

change to the directory 
terraform init
terraform plan -var-file=/home/azureuser/Terraform-Repo/module-project-practice/dev.tfvarsterraform apply -var-file=/home/azureuser/Terraform-Repo/module-project-practice/dev.tfvars

Screenshot Reference for the folder Structure

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