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Auto Scaling group does not span two or more Availability Zones Affecting EC2 service in AWS

Severity

0.0
medium
0
10
    Severity Framework
    Snyk CCSS
    Rule category
    Availability / Redundancy

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    Frameworks
    AWS-Well-Architected CSA-CCM GDPR ISO-27001 NIST-800-53 SOC-2
  • Snyk ID SNYK-CC-00167
  • credit Snyk Research Team
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Description

Auto Scaling groups that span two or more Availability Zones promote redundancy of data, which helps ensure availability and continuity during an adverse situation.

How to fix?

Set vpc_zone_identifier to two or more subnets, or set availability_zones to two or more Availability Zones.

Example Configuration

# with vpc_zone_identifier
resource "aws_autoscaling_group" "tf_asg_example" {
  name                 = "terraform-asg-example"
  vpc_zone_identifier  = [aws_subnet.subnet1.id, aws_subnet.subnet2.id]
  launch_configuration = "${aws_launch_configuration.as_conf.name}"
  min_size             = 1
  max_size             = 2

  lifecycle {
    create_before_destroy = true
  }
}

# with availability_zones
resource "aws_autoscaling_group" "example" {
  availability_zones = ["us-east-1a", "us-east-1b"]
  desired_capacity   = 1
  max_size           = 1
  min_size           = 1

  launch_template {
    id      = aws_launch_template.example.id
    version = "$Latest"
  }
}