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Aisalkyn Aidarova
Aisalkyn Aidarova

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functions, count, for_each, dynamic blocks, and production-style structure,

#aws #terraform #devops #tutorial

1. Project Structure (Production Style) 

terraform-devops-lab/
│
├── main.tf
├── provider.tf
├── variables.tf
├── outputs.tf
├── terraform.tfvars
│
├── security.tf
├── instances.tf
└── data.tf
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Terraform reads all .tf files together, but we separate them for clean architecture.

2. provider.tf

Provider configuration and Terraform settings.

terraform {

  required_version = ">= 1.5"

  required_providers {

    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }

    local = {
      source  = "hashicorp/local"
      version = "~> 2.4"
    }

  }
}

provider "aws" {
  region = var.aws_region
}
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3. variables.tf

Defines inputs.

variable "aws_region" {
  type = string
}

variable "environment" {
  type = string
}

variable "instance_types" {

  type = map(string)

  default = {
    dev  = "t2.micro"
    prod = "t2.small"
  }

}

variable "servers" {

  type = list(string)

}

variable "ports" {

  type = list(number)

}
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4. terraform.tfvars

Provides values.

aws_region = "us-east-2"

environment = "dev"

servers = [
  "web",
  "api",
  "worker"
]

ports = [22,80,443]
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5. data.tf

Production Terraform never hardcodes AMIs.

data "aws_ami" "amazon_linux" {

  most_recent = true

  owners = ["amazon"]

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

}
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6. security.tf

Security group with dynamic block.

resource "aws_security_group" "web" {

  name = "${var.environment}-web-sg"

  dynamic "ingress" {

    for_each = var.ports

    content {

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

    }

  }

}
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This automatically creates rules for:

22
80
443
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7. instances.tf

Using both count and for_each.

Count Example 

resource "aws_instance" "count_servers" {

  count = length(var.servers)

  ami           = data.aws_ami.amazon_linux.id
  instance_type = lookup(var.instance_types,var.environment)

  vpc_security_group_ids = [aws_security_group.web.id]

  tags = {

    Name = format(
      "%s-count-%s",
      var.environment,
      element(var.servers,count.index)
    )

  }

}
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Functions used here:

length()
lookup()
element()
format()
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for_each Example 

resource "aws_instance" "foreach_servers" {

  for_each = toset(var.servers)

  ami           = data.aws_ami.amazon_linux.id
  instance_type = "t2.micro"

  vpc_security_group_ids = [aws_security_group.web.id]

  tags = {

    Name = "${var.environment}-foreach-${each.value}"

  }

}
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8. main.tf

Local resource with timestamp()

resource "local_file" "deployment_info" {

  filename = "deployment.txt"

  content = format(
    "Terraform deployment time: %s",
    timestamp()
  )

}
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9. outputs.tf

Terraform outputs.

output "server_count" {

  value = length(var.servers)

}

output "security_group_id" {

  value = aws_security_group.web.id

}

output "deployment_time" {

  value = timestamp()

}
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10. Commands Practice

Initialize providers

terraform init -upgrade
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Create execution plan

terraform plan -out=infra.plan
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Apply saved plan

terraform apply infra.plan
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Target specific resource

terraform plan -target=local_file.deployment_info
terraform apply -target=local_file.deployment_info
terraform destroy -target=local_file.deployment_info
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Create only security group

terraform apply -target=aws_security_group.web
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Force recreation

terraform taint aws_instance.count_servers[0]
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Show outputs

terraform output
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Show dependency graph

terraform graph
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Generate infrastructure diagram

terraform graph | dot -Tpng > graph.png
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11. Architecture Created 

           Data Source
        (Latest Amazon AMI)
                │
                ▼
        Security Group
        Dynamic Rules
      22 / 80 / 443
                │
                ▼
        EC2 Instances
        count + for_each
                │
                ▼
        Local File
       deployment.txt
                │
                ▼
             Outputs
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12. Why This Lab Is Production-Ready

This lab teaches real Terraform patterns:

  • dynamic infrastructure
  • environment configuration
  • reusable variables
  • data sources
  • dependency graph
  • count vs for_each
  • tfvars separation
  • organized file structure

This is very close to how Terraform is used in DevOps teams.

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