Dynamic block syntax in Terraform - Mini Project: Build & Apply

Terraform Dynamic Block Syntax

📖 Scenario: You are setting up a Terraform configuration to create an AWS security group. You want to allow multiple ingress rules, but you want to use a dynamic block to define these rules based on a list of ports.

🎯 Goal: Build a Terraform configuration that uses a dynamic block to create multiple ingress rules inside an AWS security group resource.

📋 What You'll Learn

Create a variable list of ports called allowed_ports with values 22, 80, and 443

Create an AWS security group resource named example_sg

Use a dynamic block named ingress inside the security group resource

Each ingress rule should allow TCP traffic on the ports from allowed_ports from any IP

💡 Why This Matters

🌍 Real World

Dynamic blocks help manage multiple similar resource blocks efficiently, such as multiple firewall rules, without repeating code.

💼 Career

Understanding dynamic blocks is essential for Terraform users to write clean, scalable infrastructure as code, a key skill for cloud engineers and DevOps professionals.

1

Create the allowed_ports variable

Create a Terraform variable called allowed_ports of type list(number) with the exact values [22, 80, 443].

Terraform

# Your code here

Need a hint?

Use variable "allowed_ports" with type = list(number) and set default to [22, 80, 443].

2

Create the AWS security group resource

Create a Terraform resource of type aws_security_group named example_sg with a name attribute set to "example-sg".

Terraform

variable "allowed_ports" {
  type = list(number)
  default = [22, 80, 443]
}

# Your code here

Need a hint?

Use resource "aws_security_group" "example_sg" and set name = "example-sg".

3

Add the dynamic block for ingress rules

Inside the aws_security_group.example_sg resource, add a dynamic block named ingress that iterates over var.allowed_ports. For each port, create an ingress rule with from_port and to_port set to the port number, protocol set to "tcp", and cidr_blocks set to ["0.0.0.0/0"].

Terraform

variable "allowed_ports" {
  type = list(number)
  default = [22, 80, 443]
}

resource "aws_security_group" "example_sg" {
  name = "example-sg"

  # Your code here
}

Need a hint?

Use dynamic "ingress" with for_each = var.allowed_ports. Inside content, set from_port and to_port to ingress.value.

4

Complete the security group with description

Add a description attribute to the aws_security_group.example_sg resource with the exact value "Example security group with dynamic ingress rules".

Terraform

variable "allowed_ports" {
  type = list(number)
  default = [22, 80, 443]
}

resource "aws_security_group" "example_sg" {
  name = "example-sg"

  dynamic "ingress" {
    for_each = var.allowed_ports
    content {
      from_port   = ingress.value
      to_port     = ingress.value
      protocol    = "tcp"
      cidr_blocks = ["0.0.0.0/0"]
    }
  }

  # Your code here
}

Need a hint?

Add description = "Example security group with dynamic ingress rules" inside the resource block.