> For the complete documentation index, see [llms.txt](https://terraform201.devart.tv/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://terraform201.devart.tv/2./2.2-ec2-asg.md).

# EC2 ASG 생성하기

Auto Scaling Group의 주요 기능은 다음과 같습니다:

* **Elastic**: 트래픽이 증가할 때 자동으로 EC2 인스턴스를 추가하여 처리 능력을 증가시키고, 트래픽이 감소할 때는 인스턴스를 자동으로 줄여 비용을 절약할 수 있습니다.
* **High Availability**: 여러 가용 영역(Availability Zones)에 걸쳐 인스턴스를 분산시켜, 하나의 영역에 문제가 생겼을 때도 애플리케이션이 계속 작동할 수 있게 합니다.
* **Load balancing**: Auto Scaling Group은 AWS Elastic Load Balancing(ELB)과 통합되어, 인스턴스 간에 들어오는 트래픽을 자동으로 분산시킬 수 있습니다.

\
service.tf

```bash
##### ASG

resource "aws_launch_template" "lt" {
  name_prefix   = "${var.service_name}-${var.vpc_name}-LT"
  image_id      = var.image_id
  instance_type = var.instance_type
  key_name      = var.key_name

  vpc_security_group_ids = [aws_security_group.ec2.id]

  tag_specifications {
    resource_type = "instance"
    tags = {
      Name = "${var.service_name}-${var.vpc_name}-LaunchTemplate"
    }
  }
}

resource "aws_autoscaling_group" "asg" {
  launch_template {
    id      = aws_launch_template.lt.id
    version = "$Latest"

  }

  min_size         = var.min_size
  max_size         = var.max_size
  desired_capacity = var.desired_capacity
  vpc_zone_identifier = var.private_subnets

  target_group_arns = [aws_lb_target_group.internal.arn]

  tag {
    key                 = "Name"
    value               = "${var.service_name}-${var.vpc_name}-asg"
    
    propagate_at_launch = true
  }
}


```

```bash
### variables.tf

variable "image_id" {
  description = "AMI ID for instance"
  type        = string
  default     = "ami-0032724dd60a24c31"
}

variable "instance_type" {
  description = "EC2 Instance type"
  type        = string
  default     = "t3.small"
}

variable "key_name" {
  description = "EC2 key-pair"
  type        = string
}

variable "min_size" {
  description = "Auto Scaling min size"
  type        = number
  default     = 1
}

variable "max_size" {
  description = "Auto Scaling max size"
  type        = number
  default     = 1
}

variable "desired_capacity" {
  description = "Auto Scaling desired capacity"
  type        = number
  default     = 1
}

```


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