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Amazon ECS 0.36.0Last updated in version 0.35.14

ECS Cluster Module

View SourceRelease Notes

This Terraform Module launches an EC2 Container Service Cluster that you can use to run Docker containers and services (see the ecs-service module).

WARNING: Launch Configurations: Launch configurations are being phased out in favor of Launch Templates. Before upgrading to the latest release please be sure to test and plan any changes to infrastructure that may be impacted. Launch templates are being introduced in PR #371

What is an ECS Cluster?​

To use ECS with the EC2 launch type, you first deploy one or more EC2 Instances into a "cluster". The ECS scheduler can then deploy Docker containers across any of the instances in this cluster. Each instance needs to have the Amazon ECS Agent installed so it can communicate with ECS and register itself as part of the right cluster.

How do you run Docker containers on the cluster?​

See the service module.

How do you add additional security group rules?​

To add additional security group rules to the EC2 Instances in the ECS cluster, you can use the aws_security_group_rule resource, and set its security_group_id argument to the Terraform output of this module called ecs_instance_security_group_id. For example, here is how you can allow the EC2 Instances in this cluster to allow incoming HTTP requests on port 8080:

module "ecs_cluster" {
  # (arguments omitted)
}

resource "aws_security_group_rule" "allow_inbound_http_from_anywhere" {
  type = "ingress"
  from_port = 8080
  to_port = 8080
  protocol = "tcp"
  cidr_blocks = ["0.0.0.0/0"]

  security_group_id = "${module.ecs_cluster.ecs_instance_security_group_id}"
}

Note: The security group rules you add will apply to ALL Docker containers running on these EC2 Instances. There is currently no way in ECS to manage security group rules on a per-Docker-container basis.

How do you add additional IAM policies?​

To add additional IAM policies to the EC2 Instances in the ECS cluster, you can use the aws_iam_role_policy or aws_iam_policy_attachment resources, and set the IAM role id to the Terraform output of this module called ecs_instance_iam_role_name . For example, here is how you can allow the EC2 Instances in this cluster to access an S3 bucket:

module "ecs_cluster" {
  # (arguments omitted)
}

resource "aws_iam_role_policy" "access_s3_bucket" {
    name = "access_s3_bucket"
    role = "${module.ecs_cluster.ecs_instance_iam_role_name}"
    policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "",
      "Effect":"Allow",
      "Action": "s3:GetObject",
      "Resource": "arn:aws:s3:::examplebucket/*"
    }
  ]
}
EOF
}

Note: The IAM policies you add will apply to ALL Docker containers running on these EC2 Instances. There is currently no way in ECS to manage IAM policies on a per-Docker-container basis.

How do you make changes to the EC2 Instances in the cluster?​

To deploy an update to an ECS Service, see the ecs-service module. To deploy an update to the EC2 Instances in your ECS cluster, such as a new AMI, read on.

Terraform and AWS do not provide a way to automatically roll out a change to the Instances in an ECS Cluster. Due to Terraform limitations (see here for a discussion), there is currently no way to implement this purely in Terraform code. Therefore, we've created a script called roll-out-ecs-cluster-update.py that can do a zero-downtime roll out for you.

How to use the roll-out-ecs-cluster-update.py script​

First, make sure you have the latest version of the AWS Python SDK (boto3) installed (e.g. pip3 install boto3).

To deploy a change such as rolling out a new AMI to all ECS Instances:

  1. Make sure the cluster_max_size is at least twice the size of cluster_min_size. The extra capacity will be used to deploy the updated instances.

  2. Update the Terraform code with your changes (e.g. update the cluster_instance_ami variable to a new AMI).

  3. Run terraform apply.

  4. Run the script:

    python3 roll-out-ecs-cluster-update.py --asg-name ASG_NAME --cluster-name CLUSTER_NAME --aws-region AWS_REGION

    If you have your output variables configured as shown in outputs.tf of the docker-service-with-elb example, you can use the terraform output command to fill in most of the arguments automatically:

    python3 roll-out-ecs-cluster-update.py \
      --asg-name $(terragrunt output -no-color asg_name) \
      --cluster-name $(terragrunt output -no-color ecs_cluster_name) \
      --aws-region $(terragrunt output -no-color aws_region)

Note: during upgrade, if desired_capacity * 2 > max_size then ASG max size will be updated to desired_capacity * 2 for the period of upgrade, to disable this behaviour - pass --keep-max-size argument.

To avoid the need to install python dependencies on your local machine, you may choose to use Docker.

  1. Navigate to the directory that you have downloaded roll-out-ecs-cluster-update.py:

  2. If you use aws-vault, you can run the following to make your aws credentials available to the container. If you do not use aws-vault, you will have to manually use the --env option of docker run

    docker run \
        -it --rm -v "$PWD":/usr/src -w /usr/src \
        --env-file <(aws-vault exec --assume-role-ttl=1h PROFILE -- env | grep AWS) \
        python:3.10-alpine \
        sh -c "pip3 install boto3 && python3 roll-out-ecs-cluster-update.py \
        --asg-name ASG_NAME \
        --cluster-name CLUSTER_NAME \
        --aws-region AWS_REGION"

How roll-out-ecs-cluster-update.py works​

The roll-out-ecs-cluster-update.py script does the following:

  1. Double the desired capacity of the Auto Scaling Group that powers the ECS Cluster. This causes EC2 Instances to deploy with the new launch template.
  2. Put all the old ECS Instances in DRAINING state so all ECS Tasks are migrated to the new Instances.
  3. Wait for all ECS Tasks to migrate to the new Instances.
  4. Detach the now drained instances from the Auto Scaling Group, decrementing the desired capacity back to the original value.

How do you configure cluster autoscaling?​

ECS Clusters support two tiers of autoscaling:

  • Autoscaling of ECS Service and Tasks, where ECS will horizontally or vertically scale your ECS Tasks by provisioning more replicas of the Task or replacing them with Tasks that have more resources allocated to it.
  • Autoscaling of the ECS Cluster, where the AWS Autoscaling Group will horizontally scale the worker nodes by provisioning more.

The ecs-cluster module supports configuring ECS Cluster Autoscaling by leveraging ECS Capacity Providers. You can read more about how cluster autoscaling works with capacity providers in the official documentation.

To enable capacity providers for cluster autoscaling on your ECS cluster, you will want to configure the following variables:

# Turn on capacity providers for autoscaling
capacity_provider_enabled = true

# Enable Multi AZ capacity providers to balance autoscaling load across AZs. This should be true in production. Can be
# false in dev and stage.
multi_az_capacity_provider = true

# Configure target utilization for the ECS cluster. This number influences when scale out happens, and when instances
# should be scaled in. For example, a setting of 90 means that new instances will be provisioned when all instances are
# at 90% utilization, while instances that are only 10% utilized (CPU and Memory usage from tasks = 10%) will be scaled
# in. A recommended default to start with is 90.
capacity_provider_target = 90

# The following are optional configurations, and configures how many instances should be scaled out or scaled in at one
# time. Defaults to 1.
# capacity_provider_max_scale_step = 1
# capacity_provider_min_scale_step = 1

Note on toggling capacity providers on existing ECS Clusters​

Each EC2 instance must be registered with Capacity Providers to be considered in the pool. This means that when you enable Capacity Providers on an existing ECS cluster that did not have Capacity Providers, you must rotate the EC2 instances to ensure all the instances get associated with the new Capacity Provider.

To rotate the instances, you can run the roll-out-ecs-cluster-update.py script in the terraform-aws-ecs module. Refer to the documentation for more information on the script.

Sample Usage​

main.tf

# ------------------------------------------------------------------------------------------------------
# DEPLOY GRUNTWORK'S ECS-CLUSTER MODULE
# ------------------------------------------------------------------------------------------------------

module "ecs_cluster" {

  source = "git::git@github.com:gruntwork-io/terraform-aws-ecs.git//modules/ecs-cluster?ref=v0.36.0"

  # ----------------------------------------------------------------------------------------------------
  # REQUIRED VARIABLES
  # ----------------------------------------------------------------------------------------------------

  # The AMI to run on each of the ECS Cluster's EC2 Instances.
  cluster_instance_ami = <string>

  # The EC2 Keypair name used to SSH into the ECS Cluster's EC2 Instances.
  cluster_instance_keypair_name = <string>

  # The type of EC2 instance to run for each of the ECS Cluster's EC2 Instances
  # (e.g. t2.medium).
  cluster_instance_type = <string>

  # The maximum number of EC2 Instances that must be running for this ECS
  # Cluster. We recommend making this twice var.cluster_min_size, even if you
  # don't plan on scaling the cluster up and down, as the extra capacity will be
  # used to deploy udpates to the cluster.
  cluster_max_size = <number>

  # The minimum number of EC2 Instances launchable for this ECS Cluster. Useful
  # for auto-scaling limits.
  cluster_min_size = <number>

  # The name of the ECS cluster (e.g. ecs-prod). This is used to namespace all
  # the resources created by these templates.
  cluster_name = <string>

  # The ID of the VPC in which the ECS Cluster's EC2 Instances will reside.
  vpc_id = <string>

  # A list of the subnets into which the ECS Cluster's EC2 Instances will be
  # launched. These should usually be all private subnets and include one in
  # each AWS Availability Zone.
  vpc_subnet_ids = <list(string)>

  # ----------------------------------------------------------------------------------------------------
  # OPTIONAL VARIABLES
  # ----------------------------------------------------------------------------------------------------

  # A list of Security Group IDs of the ALBs which will send traffic to this ECS
  # Cluster.
  alb_security_group_ids = []

  # The IP address ranges in CIDR format from which to allow incoming SSH
  # requests to the ECS instances.
  allow_ssh_from_cidr_blocks = []

  # The IDs of security groups from which to allow incoming SSH requests to the
  # ECS instances.
  allow_ssh_from_security_group_ids = []

  # Protect EC2 instances running ECS tasks from being terminated due to scale
  # in (spot instances do not support lifecycle modifications)
  autoscaling_termination_protection = false

  # Enable a capacity provider to autoscale the EC2 ASG created for this ECS
  # cluster
  capacity_provider_enabled = false

  # Maximum step adjustment size to the ASG's desired instance count
  capacity_provider_max_scale_step = 10

  # Minimum step adjustment size to the ASG's desired instance count
  capacity_provider_min_scale_step = 1

  # Target cluster utilization for the capacity provider; a number from 1 to
  # 100.
  capacity_provider_target = 75

  # A list of metrics to collect. The allowed values are GroupDesiredCapacity,
  # GroupInServiceCapacity, GroupPendingCapacity, GroupMinSize, GroupMaxSize,
  # GroupInServiceInstances, GroupPendingInstances, GroupStandbyInstances,
  # GroupStandbyCapacity, GroupTerminatingCapacity, GroupTerminatingInstances,
  # GroupTotalCapacity, GroupTotalInstances.
  cluster_asg_metrics_enabled = []

  # Enables/disables detailed CloudWatch monitoring for EC2 instances
  cluster_detailed_monitoring = true

  # Passthrough to aws_launch_template resource.  Associate a public ip address
  # with EC2 instances in cluster
  cluster_instance_associate_public_ip_address = false

  # The name of the device to mount.
  cluster_instance_block_device_name = "/dev/xvdcz"

  # Whether the volume should be destroyed on instance termination. Defaults to
  # false
  cluster_instance_ebs_delete_on_termination = false

  # The amount of provisioned IOPS. This must be set with a volume_type of
  # io1/io2.
  cluster_instance_ebs_iops = null

  # The ARN of the AWS Key Management Service (AWS KMS) customer master key
  # (CMK) to use when creating the encrypted volume. The variable
  # cluster_instance_root_volume_encrypted must be set to true when this is set.
  cluster_instance_ebs_kms_key_id = null

  # If true, the launched EC2 instance will be EBS-optimized
  cluster_instance_ebs_optimized = false

  # The Snapshot ID to mount.
  cluster_instance_ebs_snapshot_id = null

  # The throughput to provision for a gp3 volume in MiB/s (specified as an
  # integer, e.g., 500), with a maximum of 1,000 MiB/s.
  cluster_instance_ebs_throughput = null

  # The required duration in minutes. This value must be a multiple of 60.
  cluster_instance_market_block_duration_minutes = null

  # The behavior when a Spot Instance is interrupted. Can be hibernate, stop, or
  # terminate. (Default: terminate).
  cluster_instance_market_instance_interruption_behavior = "terminate"

  # The Spot Instance request type. Can be one-time, or persistent.
  cluster_instance_market_spot_instance_type = null

  # The end date of the request.
  cluster_instance_market_valid_until = null

  # The affinity setting for an instance on a Dedicated Host.
  cluster_instance_placement_affinity = null

  # The name of the placement group for the instance.
  cluster_instance_placement_group_name = null

  # The ID of the Dedicated Host for the instance.
  cluster_instance_placement_host_id = null

  # The ARN of the Host Resource Group in which to launch instances.
  cluster_instance_placement_host_resource_group_arn = null

  # The number of the partition the instance should launch in. Valid only if the
  # placement group strategy is set to partition.
  cluster_instance_placement_partition_number = null

  # Set to true to request spot instances. Set cluster_instance_spot_price
  # variable to set a maximum spot price limit.
  cluster_instance_request_spot_instances = false

  # The ARN of the policy that is used to set the permissions boundary for the
  # IAM role for the cluster instances.
  cluster_instance_role_permissions_boundary_arn = null

  # Set to true to encrypt the root block devices for the ECS cluster's EC2
  # instances
  cluster_instance_root_volume_encrypted = false

  # The size in GB of the root volume for each of the ECS Cluster's EC2
  # Instances
  cluster_instance_root_volume_size = 40

  # The volume type for the root volume for each of the ECS Cluster's EC2
  # Instances. Can be standard, gp2, or io1
  cluster_instance_root_volume_type = "gp2"

  # Value is the maximum bid price for the instance on the EC2 Spot Market.
  cluster_instance_spot_price = null

  # The User Data script to run on each of the ECS Cluster's EC2 Instances on
  # their first boot.
  cluster_instance_user_data = null

  # The base64-encoded User Data script to run on the server when it is booting.
  # This can be used to pass binary User Data, such as a gzipped cloud-init
  # script. If you wish to pass in plain text (e.g., typical Bash script) for
  # User Data, use var.cluster_instance_user_data instead.
  cluster_instance_user_data_base64 = null

  # If you set this variable to false, this module will not create any
  # resources. This is used as a workaround because Terraform does not allow you
  # to use the 'count' parameter on modules. By using this parameter, you can
  # optionally create or not create the resources within this module.
  create_resources = true

  # When set, name the IAM role for the ECS cluster using this variable. When
  # null, the IAM role name will be derived from var.cluster_name.
  custom_iam_role_name = null

  # A list of custom tags to apply to the EC2 Instances in this ASG. Each item
  # in this list should be a map with the parameters key, value, and
  # propagate_at_launch.
  custom_tags_ec2_instances = []

  # Custom tags to apply to the ECS cluster
  custom_tags_ecs_cluster = {}

  # A map of custom tags to apply to the Security Group for this ECS Cluster.
  # The key is the tag name and the value is the tag value.
  custom_tags_security_group = {}

  # Enables additional block device mapping. Change to false if you wish to
  # disable additional EBS volume attachment to EC2 instances. Defaults to true.
  enable_block_device_mappings = true

  # Whether or not to enable Container Insights on the ECS cluster. Refer to
  # https://docs.aws.amazon.com/AmazonECS/latest/developerguide/cloudwatch-container-insights.html
  # for more information on ECS Container Insights.
  enable_cluster_container_insights = false

  # Set this variable to true to enable the Instance Metadata Service (IMDS)
  # endpoint, which is used to fetch information such as user-data scripts,
  # instance IP address and region, etc. Set this variable to false if you do
  # not want the IMDS endpoint enabled for instances launched into the Auto
  # Scaling Group for the workers.
  enable_imds = true

  # The desired HTTP PUT response hop limit for instance metadata requests.
  http_put_response_hop_limit = null

  # Override default parameters for Instance Refresh. See
  # https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/autoscaling_group#preferences
  # for available options
  instance_refresh_preferences = {}

  # Strategy to use for instance refresh. If not specified then instance_refresh
  # is disabled
  instance_refresh_strategy = null

  # Maximum amount of time, in seconds, that an instance can be in service,
  # values must be either equal to 0 or between 86400 and 31536000 seconds.
  max_instance_lifetime = null

  # Enable a multi-az capacity provider to autoscale the EC2 ASGs created for
  # this ECS cluster, only if capacity_provider_enabled = true
  multi_az_capacity_provider = false

  # The port to use for SSH access.
  ssh_port = 22

  # The tenancy of the servers in this cluster. Must be one of: default,
  # dedicated, or host.
  tenancy = "default"

  # A list of policies to decide how the instances in the auto scale group
  # should be terminated. The allowed values are OldestInstance, NewestInstance,
  # OldestLaunchConfiguration, ClosestToNextInstanceHour, OldestLaunchTemplate,
  # AllocationStrategy, Default. If you specify more than one policy, the ASG
  # will try each one in turn, use it to select the instance(s) to terminate,
  # and if more than one instance matches the criteria, then use the next policy
  # to try to break the tie. E.g., If you use ['OldestInstance',
  # 'ClosestToNextInstanceHour'] and and there were two instances with exactly
  # the same launch time, then the ASG would try the next policy, which is to
  # terminate the one closest to the next instance hour in billing.
  termination_policies = ["OldestInstance"]

  # Set this variable to true to enable the use of Instance Metadata Service
  # Version 1 in this module's aws_launch_template. Note that while IMDsv2 is
  # preferred due to its special security hardening, we allow this in order to
  # support the use case of AMIs built outside of these modules that depend on
  # IMDSv1.
  use_imdsv1 = true

}


Reference​

Required​

cluster_instance_amistringrequired

The AMI to run on each of the ECS Cluster's EC2 Instances.

The EC2 Keypair name used to SSH into the ECS Cluster's EC2 Instances.

cluster_instance_typestringrequired

The type of EC2 instance to run for each of the ECS Cluster's EC2 Instances (e.g. t2.medium).

cluster_max_sizenumberrequired

The maximum number of EC2 Instances that must be running for this ECS Cluster. We recommend making this twice cluster_min_size, even if you don't plan on scaling the cluster up and down, as the extra capacity will be used to deploy udpates to the cluster.

cluster_min_sizenumberrequired

The minimum number of EC2 Instances launchable for this ECS Cluster. Useful for auto-scaling limits.

cluster_namestringrequired

The name of the ECS cluster (e.g. ecs-prod). This is used to namespace all the resources created by these templates.

vpc_idstringrequired

The ID of the VPC in which the ECS Cluster's EC2 Instances will reside.

vpc_subnet_idslist(string)required

A list of the subnets into which the ECS Cluster's EC2 Instances will be launched. These should usually be all private subnets and include one in each AWS Availability Zone.

Optional​

alb_security_group_idslist(string)optional

A list of Security Group IDs of the ALBs which will send traffic to this ECS Cluster.

[]
allow_ssh_from_cidr_blockslist(string)optional

The IP address ranges in CIDR format from which to allow incoming SSH requests to the ECS instances.

[]

The IDs of security groups from which to allow incoming SSH requests to the ECS instances.

[]

Protect EC2 instances running ECS tasks from being terminated due to scale in (spot instances do not support lifecycle modifications)

false

Enable a capacity provider to autoscale the EC2 ASG created for this ECS cluster

false

Maximum step adjustment size to the ASG's desired instance count

10

Minimum step adjustment size to the ASG's desired instance count

1

Target cluster utilization for the capacity provider; a number from 1 to 100.

75
cluster_asg_metrics_enabledlist(string)optional

A list of metrics to collect. The allowed values are GroupDesiredCapacity, GroupInServiceCapacity, GroupPendingCapacity, GroupMinSize, GroupMaxSize, GroupInServiceInstances, GroupPendingInstances, GroupStandbyInstances, GroupStandbyCapacity, GroupTerminatingCapacity, GroupTerminatingInstances, GroupTotalCapacity, GroupTotalInstances.

[]

Enables/disables detailed CloudWatch monitoring for EC2 instances

true

Passthrough to aws_launch_template resource. Associate a public ip address with EC2 instances in cluster

false

The name of the device to mount.

"/dev/xvdcz"

Whether the volume should be destroyed on instance termination. Defaults to false

false

The amount of provisioned IOPS. This must be set with a volume_type of io1/io2.

null

The ARN of the AWS Key Management Service (AWS KMS) customer master key (CMK) to use when creating the encrypted volume. The variable cluster_instance_root_volume_encrypted must be set to true when this is set.

null

If true, the launched EC2 instance will be EBS-optimized

false

The Snapshot ID to mount.

null

The throughput to provision for a gp3 volume in MiB/s (specified as an integer, e.g., 500), with a maximum of 1,000 MiB/s.

null

The required duration in minutes. This value must be a multiple of 60.

null

The behavior when a Spot Instance is interrupted. Can be hibernate, stop, or terminate. (Default: terminate).

"terminate"

The Spot Instance request type. Can be one-time, or persistent.

null

The end date of the request.

null

The affinity setting for an instance on a Dedicated Host.

null

The name of the placement group for the instance.

null

The ID of the Dedicated Host for the instance.

null

The ARN of the Host Resource Group in which to launch instances.

null

The number of the partition the instance should launch in. Valid only if the placement group strategy is set to partition.

null

Set to true to request spot instances. Set cluster_instance_spot_price variable to set a maximum spot price limit.

false

The ARN of the policy that is used to set the permissions boundary for the IAM role for the cluster instances.

null

Set to true to encrypt the root block devices for the ECS cluster's EC2 instances

false

The size in GB of the root volume for each of the ECS Cluster's EC2 Instances

40

The volume type for the root volume for each of the ECS Cluster's EC2 Instances. Can be standard, gp2, or io1

"gp2"

Value is the maximum bid price for the instance on the EC2 Spot Market.

null

The User Data script to run on each of the ECS Cluster's EC2 Instances on their first boot.

null

The base64-encoded User Data script to run on the server when it is booting. This can be used to pass binary User Data, such as a gzipped cloud-init script. If you wish to pass in plain text (e.g., typical Bash script) for User Data, use cluster_instance_user_data instead.

null
create_resourcesbooloptional

If you set this variable to false, this module will not create any resources. This is used as a workaround because Terraform does not allow you to use the 'count' parameter on modules. By using this parameter, you can optionally create or not create the resources within this module.

true
custom_iam_role_namestringoptional

When set, name the IAM role for the ECS cluster using this variable. When null, the IAM role name will be derived from cluster_name.

null

A list of custom tags to apply to the EC2 Instances in this ASG. Each item in this list should be a map with the parameters key, value, and propagate_at_launch.

[]
custom_tags_ecs_clustermap(string)optional

Custom tags to apply to the ECS cluster

{}
custom_tags_security_groupmap(string)optional

A map of custom tags to apply to the Security Group for this ECS Cluster. The key is the tag name and the value is the tag value.

{}

Enables additional block device mapping. Change to false if you wish to disable additional EBS volume attachment to EC2 instances. Defaults to true.

true

Whether or not to enable Container Insights on the ECS cluster. Refer to https://docs.aws.amazon.com/AmazonECS/latest/developerguide/cloudwatch-container-insights.html for more information on ECS Container Insights.

false
Details

   We intentionally default this to false. While Container Insights provides useful metrics, the costs can add up
   depending on how large your clusters are. Specifically, Container Insights will add:
   - 8 custom metrics per ECS cluster
   - 6 custom metrics per ECS task
   - 11 custom metrics per ECS service
   Each metric costs $0.30 per month up to 10,000 metrics, at which point the costs start to drop. Refer to
   https://aws.amazon.com/cloudwatch/pricing/ for more details.

enable_imdsbooloptional

Set this variable to true to enable the Instance Metadata Service (IMDS) endpoint, which is used to fetch information such as user-data scripts, instance IP address and region, etc. Set this variable to false if you do not want the IMDS endpoint enabled for instances launched into the Auto Scaling Group for the workers.

true

The desired HTTP PUT response hop limit for instance metadata requests.

null

Override default parameters for Instance Refresh. See https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/autoscaling_group#preferences for available options

Any types represent complex values of variable type. For details, please consult `variables.tf` in the source repo.
{}

Strategy to use for instance refresh. If not specified then instance_refresh is disabled

null
max_instance_lifetimenumberoptional

Maximum amount of time, in seconds, that an instance can be in service, values must be either equal to 0 or between 86400 and 31536000 seconds.

null

Enable a multi-az capacity provider to autoscale the EC2 ASGs created for this ECS cluster, only if capacity_provider_enabled = true

false
ssh_portnumberoptional

The port to use for SSH access.

22
tenancystringoptional

The tenancy of the servers in this cluster. Must be one of: default, dedicated, or host.

"default"
termination_policieslist(string)optional

A list of policies to decide how the instances in the auto scale group should be terminated. The allowed values are OldestInstance, NewestInstance, OldestLaunchConfiguration, ClosestToNextInstanceHour, OldestLaunchTemplate, AllocationStrategy, Default. If you specify more than one policy, the ASG will try each one in turn, use it to select the instance(s) to terminate, and if more than one instance matches the criteria, then use the next policy to try to break the tie. E.g., If you use ['OldestInstance', 'ClosestToNextInstanceHour'] and and there were two instances with exactly the same launch time, then the ASG would try the next policy, which is to terminate the one closest to the next instance hour in billing.

[
  "OldestInstance"
]
use_imdsv1booloptional

Set this variable to true to enable the use of Instance Metadata Service Version 1 in this module's aws_launch_template. Note that while IMDsv2 is preferred due to its special security hardening, we allow this in order to support the use case of AMIs built outside of these modules that depend on IMDSv1.

true