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Aisalkyn Aidarova
Aisalkyn Aidarova

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Advanced Terraform Lab (Production Style)

#aws #devops #terraform #tutorial

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
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PROD

3 EC2 instances
t2.small
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Security group rules created dynamically.

Step 1 — Create Project 

mkdir terraform-advanced-lab
cd terraform-advanced-lab
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Create files

main.tf
variables.tf
outputs.tf
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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)
}
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This introduces students to complex data structures.

Example structure:

map(object({
instance_type
name
}))
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Step 3 — main.tf

Provider configuration.

provider "aws" {
  region = var.aws_region
}
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Get Latest AMI 

data "aws_ami" "amazon_linux" {

  most_recent = true
  owners = ["amazon"]

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

  }

}
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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"]

    }

  }

}
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This uses dynamic blocks.

If ports list is:

[22,80,443]
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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
  }

}
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Important:

Concept Meaning
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"]
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Step 7 — outputs.tf 

output "instance_public_ips" {

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

}
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Example output:

prod-web1 = 18.120.x.x
prod-web2 = 3.19.x.x
prod-web3 = 54.193.x.x
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Step 8 — Initialize Terraform 

terraform init
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Step 9 — Create Workspaces

DEV workspace

terraform workspace new dev
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Switch

terraform workspace select dev
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Deploy

terraform apply
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Result:

1 EC2 instance
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Step 10 — Create PROD Environment

Create workspace

terraform workspace new prod
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Switch

terraform workspace select prod
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Deploy

terraform apply
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Result:

3 EC2 instances
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Step 11 — Verify Workspaces 

terraform workspace list
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Output

default
dev
prod
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What Students Learn

This lab teaches real production Terraform skills:

Concept Why Important
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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