Advanced Terraform Lab (Production Style)

[MyrinNew]

Topics covered:

• for_each
• map variables
• locals
• dynamic blocks
• terraform workspaces
• multi-environment deployment

Goal

Deploy multiple EC2 servers with different configurations using:

• for_each
• map variables
• locals
• dynamic blocks
• terraform workspaces

Architecture

DEV






1 EC2 instance
t2.micro







PROD






3 EC2 instances
t2.small







Security group rules created dynamically.





Step 1 — Create Project





mkdir terraform-advanced-lab
cd terraform-advanced-lab







Create files






main.tf
variables.tf
outputs.tf










Step 2 — variables.tf

Introduce map and list data types.






variable "aws_region" {
type = string
default = "us-east-2"
}

variable "instances" {
description = "EC2 instances configuration"
type = map(object({
instance_type = string
name = string
}))
}

variable "security_ports" {
type = list(number)
}







This introduces students to complex data structures.


Example structure:






map(object({
instance_type
name
}))










Step 3 — main.tf

Provider configuration.






provider "aws" {
region = var.aws_region
}










Get Latest AMI





data "aws_ami" "amazon_linux" {

most_recent = true
owners = ["amazon"]

filter {
name = "name"
values = ["amzn2-ami-hvm-*-x86_64-gp2"]
}
}










Step 4 — Locals

Locals help create environment logic.






locals {

environment = terraform.workspace

instance_config = local.environment == "prod" ? {

web1 = {
instance_type = "t2.small"
name = "prod-web1"
}

web2 = {
instance_type = "t2.small"
name = "prod-web2"
}

web3 = {
instance_type = "t2.small"
name = "prod-web3"
}

} : {

web1 = {
instance_type = "t2.micro"
name = "dev-web1"
}

}

}







This is real enterprise logic.


Environment decides infrastructure size.





Step 5 — Security Group





resource "aws_security_group" "web_sg" {

name = "web-security-group"

dynamic "ingress" {

for_each = var.security_ports

content {

from_port = ingress.value
to_port = ingress.value
protocol = "tcp"
cidr_blocks = ["0.0.0.0/0"]

}

}

}







This uses dynamic blocks.


If ports list is:






[22,80,443]







Terraform creates 3 ingress rules automatically.





Step 6 — EC2 Instances using for_each





resource "aws_instance" "web" {

for_each = local.instance_config

ami = data.aws_ami.amazon_linux.id
instance_type = each.value.instance_type

vpc_security_group_ids = [
aws_security_group.web_sg.id
]

tags = {
Name = each.value.name
Environment = local.environment
}

}







Important:

for_each	creates resources from map
each.key	map key
each.value	map value

Example Terraform creates:






aws_instance.web["web1"]
aws_instance.web["web2"]
aws_instance.web["web3"]










Step 7 — outputs.tf





output "instance_public_ips" {

value = {
for instance in aws_instance.web :
instance.tags.Name => instance.public_ip
}

}







Example output:






prod-web1 = 18.120.x.x
prod-web2 = 3.19.x.x
prod-web3 = 54.193.x.x










Step 8 — Initialize Terraform





terraform init










Step 9 — Create Workspaces

DEV workspace






terraform workspace new dev







Switch






terraform workspace select dev







Deploy






terraform apply







Result:






1 EC2 instance










Step 10 — Create PROD Environment

Create workspace






terraform workspace new prod







Switch






terraform workspace select prod







Deploy






terraform apply







Result:






3 EC2 instances










Step 11 — Verify Workspaces





terraform workspace list







Output






default
dev
prod










What Students Learn

This lab teaches real production Terraform skills:

for_each	used in almost every real Terraform project
locals	simplify environment logic
dynamic blocks	avoid repeated code
maps & objects	advanced variable types
workspaces	multi-environment infrastructure

DevOps Interview Questions from this Lab

1️⃣ Difference between count vs for_each


2️⃣ What is terraform workspace


3️⃣ What are locals


4️⃣ What are dynamic blocks


5️⃣ When should you use map vs list


6️⃣ Why is for_each safer than count




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