terraform-aws-ec2-autoscale-group

Terraform module to provision Auto Scaling Group and Launch Template on AWS.

The module also creates AutoScaling Policies and CloudWatch Metric Alarms to monitor CPU utilization on the EC2 instances and scale the number of instance in the AutoScaling Group up or down. If you don't want to use the provided functionality, or want to provide your own policies, disable it by setting the variable autoscaling_policies_enabled to false.

At present, although you can set the created AutoScaling Policy type to any legal value, in practice only SimpleScaling is supported. To use a StepScaling or TargetTrackingScaling policy, create it yourself and then pass it in the alarm_actions field of custom_alarms.

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Security & Compliance

Security scanning is graciously provided by Bridgecrew. Bridgecrew is the leading fully hosted, cloud-native solution providing continuous Terraform security and compliance.

Benchmark	Description
	Infrastructure Security Compliance
	Center for Internet Security, KUBERNETES Compliance
	Center for Internet Security, AWS Compliance
	Center for Internet Security, AZURE Compliance
	Payment Card Industry Data Security Standards Compliance
	National Institute of Standards and Technology Compliance
	Information Security Management System, ISO/IEC 27001 Compliance
	Service Organization Control 2 Compliance
	Center for Internet Security, GCP Compliance
	Health Insurance Portability and Accountability Compliance

Usage

IMPORTANT: We do not pin modules to versions in our examples because of the difficulty of keeping the versions in the documentation in sync with the latest released versions. We highly recommend that in your code you pin the version to the exact version you are using so that your infrastructure remains stable, and update versions in a systematic way so that they do not catch you by surprise.

Also, because of a bug in the Terraform registry (hashicorp/terraform#21417), the registry shows many of our inputs as required when in fact they are optional. The table below correctly indicates which inputs are required.

locals {
  userdata = <<-USERDATA
    #!/bin/bash
    cat <<"__EOF__" > /home/ec2-user/.ssh/config
    Host *
      StrictHostKeyChecking no
    __EOF__
    chmod 600 /home/ec2-user/.ssh/config
    chown ec2-user:ec2-user /home/ec2-user/.ssh/config
  USERDATA
}

module "autoscale_group" {
  source = "cloudposse/ec2-autoscale-group/aws"
  # Cloud Posse recommends pinning every module to a specific version
  # version = "x.x.x"

  namespace   = var.namespace
  stage       = var.stage
  environment = var.environment
  name        = var.name

  image_id                    = "ami-08cab282f9979fc7a"
  instance_type               = "t2.small"
  security_group_ids          = ["sg-xxxxxxxx"]
  subnet_ids                  = ["subnet-xxxxxxxx", "subnet-yyyyyyyy", "subnet-zzzzzzzz"]
  health_check_type           = "EC2"
  min_size                    = 2
  max_size                    = 3
  wait_for_capacity_timeout   = "5m"
  associate_public_ip_address = true
  user_data_base64            = base64encode(local.userdata)

  # All inputs to `block_device_mappings` have to be defined
  block_device_mappings = [
    {
      device_name  = "/dev/sda1"
      no_device    = "false"
      virtual_name = "root"
      ebs = {
        encrypted             = true
        volume_size           = 200
        delete_on_termination = true
        iops                  = null
        kms_key_id            = null
        snapshot_id           = null
        volume_type           = "standard"
      }
    }
  ]

  tags = {
    Tier              = "1"
    KubernetesCluster = "us-west-2.testing.cloudposse.co"
  }

  # Auto-scaling policies and CloudWatch metric alarms
  autoscaling_policies_enabled           = true
  cpu_utilization_high_threshold_percent = "70"
  cpu_utilization_low_threshold_percent  = "20"
}

To enable custom_alerts the map needs to be defined like so :

alarms = {
    alb_scale_up = {
      alarm_name                = "${module.default_label.id}-alb-target-response-time-for-scale-up"
      comparison_operator       = "GreaterThanThreshold"
      evaluation_periods        = var.alb_target_group_alarms_evaluation_periods
      metric_name               = "TargetResponseTime"
      namespace                 = "AWS/ApplicationELB"
      period                    = var.alb_target_group_alarms_period
      statistic                 = "Average"
      threshold                 = var.alb_target_group_alarms_response_time_max_threshold
      dimensions_name           = "LoadBalancer"
      dimensions_target         = data.alb.arn_suffix
      treat_missing_data        = "missing"
      ok_actions                = var.alb_target_group_alarms_ok_actions
      insufficient_data_actions = var.alb_target_group_alarms_insufficient_data_actions
      alarm_description         = "ALB Target response time is over ${var.alb_target_group_alarms_response_time_max_threshold} for more than ${var.alb_target_group_alarms_period}"
      alarm_actions             = [module.autoscaling.scale_up_policy_arn]
    }
}

All those keys are required to be there so if the alarm you are setting does not requiere one or more keys you can just set to empty but do not remove the keys otherwise you could get a weird merge error due to the maps being of different sizes.

Makefile Targets

Available targets:

  help                                Help screen
  help/all                            Display help for all targets
  help/short                          This help short screen
  lint                                Lint terraform code

Requirements

Name	Version
terraform	>= 0.13
aws	>= 2.0
null	>= 2.0
template	>= 2.0

Providers

Name	Version
aws	>= 2.0

Modules

Name	Source	Version
this	cloudposse/label/null	0.24.1

Resources

Name	Type
aws_autoscaling_group.default	resource
aws_autoscaling_policy.scale_down	resource
aws_autoscaling_policy.scale_up	resource
aws_cloudwatch_metric_alarm.all_alarms	resource
aws_launch_template.default	resource

Inputs

Name	Description	Type	Default	Required
additional_tag_map	Additional tags for appending to tags_as_list_of_maps. Not added to `tags`.	`map(string)`	`{}`	no
associate_public_ip_address	Associate a public IP address with an instance in a VPC	`bool`	`false`	no
attributes	Additional attributes (e.g. `1`)	`list(string)`	`[]`	no
autoscaling_policies_enabled	Whether to create `aws_autoscaling_policy` and `aws_cloudwatch_metric_alarm` resources to control Auto Scaling	`bool`	`true`	no
block_device_mappings	Specify volumes to attach to the instance besides the volumes specified by the AMI	list(object({ device_name = string no_device = bool virtual_name = string ebs = object({ delete_on_termination = bool encrypted = bool iops = number kms_key_id = string snapshot_id = string volume_size = number volume_type = string }) }))	`[]`	no
context	Single object for setting entire context at once. See description of individual variables for details. Leave string and numeric variables as `null` to use default value. Individual variable settings (non-null) override settings in context object, except for attributes, tags, and additional_tag_map, which are merged.	`any`	{ "additional_tag_map": {}, "attributes": [], "delimiter": null, "enabled": true, "environment": null, "id_length_limit": null, "label_key_case": null, "label_order": [], "label_value_case": null, "name": null, "namespace": null, "regex_replace_chars": null, "stage": null, "tags": {} }	no
cpu_utilization_high_evaluation_periods	The number of periods over which data is compared to the specified threshold	`number`	`2`	no
cpu_utilization_high_period_seconds	The period in seconds over which the specified statistic is applied	`number`	`300`	no
cpu_utilization_high_statistic	The statistic to apply to the alarm's associated metric. Either of the following is supported: `SampleCount`, `Average`, `Sum`, `Minimum`, `Maximum`	`string`	`"Average"`	no
cpu_utilization_high_threshold_percent	The value against which the specified statistic is compared	`number`	`90`	no
cpu_utilization_low_evaluation_periods	The number of periods over which data is compared to the specified threshold	`number`	`2`	no
cpu_utilization_low_period_seconds	The period in seconds over which the specified statistic is applied	`number`	`300`	no
cpu_utilization_low_statistic	The statistic to apply to the alarm's associated metric. Either of the following is supported: `SampleCount`, `Average`, `Sum`, `Minimum`, `Maximum`	`string`	`"Average"`	no
cpu_utilization_low_threshold_percent	The value against which the specified statistic is compared	`number`	`10`	no
credit_specification	Customize the credit specification of the instances	object({ cpu_credits = string })	`null`	no
custom_alarms	Map of custom CloudWatch alarms configurations	map(object({ alarm_name = string comparison_operator = string evaluation_periods = string metric_name = string namespace = string period = string statistic = string threshold = string treat_missing_data = string ok_actions = list(string) insufficient_data_actions = list(string) dimensions_name = string dimensions_target = string alarm_description = string alarm_actions = list(string) }))	`{}`	no
default_alarms_enabled	Enable or disable cpu and memory Cloudwatch alarms	`bool`	`true`	no
default_cooldown	The amount of time, in seconds, after a scaling activity completes before another scaling activity can start	`number`	`300`	no
delimiter	Delimiter to be used between `namespace`, `environment`, `stage`, `name` and `attributes`. Defaults to `-` (hyphen). Set to `""` to use no delimiter at all.	`string`	`null`	no
desired_capacity	The number of Amazon EC2 instances that should be running in the group, if not set will use `min_size` as value	`number`	`null`	no
disable_api_termination	If `true`, enables EC2 Instance Termination Protection	`bool`	`false`	no
ebs_optimized	If true, the launched EC2 instance will be EBS-optimized	`bool`	`false`	no
elastic_gpu_specifications	Specifications of Elastic GPU to attach to the instances	object({ type = string })	`null`	no
enable_monitoring	Enable/disable detailed monitoring	`bool`	`true`	no
enabled	Set to false to prevent the module from creating any resources	`bool`	`null`	no
enabled_metrics	A list of metrics to collect. The allowed values are `GroupMinSize`, `GroupMaxSize`, `GroupDesiredCapacity`, `GroupInServiceInstances`, `GroupPendingInstances`, `GroupStandbyInstances`, `GroupTerminatingInstances`, `GroupTotalInstances`	`list(string)`	[ "GroupMinSize", "GroupMaxSize", "GroupDesiredCapacity", "GroupInServiceInstances", "GroupPendingInstances", "GroupStandbyInstances", "GroupTerminatingInstances", "GroupTotalInstances" ]	no
environment	Environment, e.g. 'uw2', 'us-west-2', OR 'prod', 'staging', 'dev', 'UAT'	`string`	`null`	no
force_delete	Allows deleting the autoscaling group without waiting for all instances in the pool to terminate. You can force an autoscaling group to delete even if it's in the process of scaling a resource. Normally, Terraform drains all the instances before deleting the group. This bypasses that behavior and potentially leaves resources dangling	`bool`	`false`	no
health_check_grace_period	Time (in seconds) after instance comes into service before checking health	`number`	`300`	no
health_check_type	Controls how health checking is done. Valid values are `EC2` or `ELB`	`string`	`"EC2"`	no
iam_instance_profile_name	The IAM instance profile name to associate with launched instances	`string`	`""`	no
id_length_limit	Limit `id` to this many characters (minimum 6). Set to `0` for unlimited length. Set to `null` for default, which is `0`. Does not affect `id_full`.	`number`	`null`	no
image_id	The EC2 image ID to launch	`string`	`""`	no
instance_initiated_shutdown_behavior	Shutdown behavior for the instances. Can be `stop` or `terminate`	`string`	`"terminate"`	no
instance_market_options	The market (purchasing) option for the instances	object({ market_type = string spot_options = object({ block_duration_minutes = number instance_interruption_behavior = string max_price = number spot_instance_type = string valid_until = string }) })	`null`	no
instance_refresh	The instance refresh definition	object({ strategy = string preferences = object({ instance_warmup = number min_healthy_percentage = number }) triggers = list(string) })	`null`	no
instance_type	Instance type to launch	`string`	n/a	yes
key_name	The SSH key name that should be used for the instance	`string`	`""`	no
label_key_case	The letter case of label keys (`tag` names) (i.e. `name`, `namespace`, `environment`, `stage`, `attributes`) to use in `tags`. Possible values: `lower`, `title`, `upper`. Default value: `title`.	`string`	`null`	no
label_order	The naming order of the id output and Name tag. Defaults to ["namespace", "environment", "stage", "name", "attributes"]. You can omit any of the 5 elements, but at least one must be present.	`list(string)`	`null`	no
label_value_case	The letter case of output label values (also used in `tags` and `id`). Possible values: `lower`, `title`, `upper` and `none` (no transformation). Default value: `lower`.	`string`	`null`	no
launch_template_version	Launch template version. Can be version number, `$Latest` or `$Default`	`string`	`"$Latest"`	no
load_balancers	A list of elastic load balancer names to add to the autoscaling group names. Only valid for classic load balancers. For ALBs, use `target_group_arns` instead	`list(string)`	`[]`	no
max_instance_lifetime	The maximum amount of time, in seconds, that an instance can be in service, values must be either equal to 0 or between 604800 and 31536000 seconds	`number`	`null`	no
max_size	The maximum size of the autoscale group	`number`	n/a	yes
metadata_http_endpoint_enabled	Set false to disable the Instance Metadata Service.	`bool`	`true`	no
metadata_http_put_response_hop_limit	The desired HTTP PUT response hop limit (between 1 and 64) for Instance Metadata Service requests. The default is `2` to support containerized workloads.	`number`	`2`	no
metadata_http_tokens_required	Set true to require IMDS session tokens, disabling Instance Metadata Service Version 1.	`bool`	`true`	no
metrics_granularity	The granularity to associate with the metrics to collect. The only valid value is 1Minute	`string`	`"1Minute"`	no
min_elb_capacity	Setting this causes Terraform to wait for this number of instances to show up healthy in the ELB only on creation. Updates will not wait on ELB instance number changes	`number`	`0`	no
min_size	The minimum size of the autoscale group	`number`	n/a	yes
mixed_instances_policy	policy to used mixed group of on demand/spot of differing types. Launch template is automatically generated. https://www.terraform.io/docs/providers/aws/r/autoscaling_group.html#mixed_instances_policy-1	object({ instances_distribution = object({ on_demand_allocation_strategy = string on_demand_base_capacity = number on_demand_percentage_above_base_capacity = number spot_allocation_strategy = string spot_instance_pools = number spot_max_price = string }) override = list(object({ instance_type = string weighted_capacity = number })) })	`null`	no
name	Solution name, e.g. 'app' or 'jenkins'	`string`	`null`	no
namespace	Namespace, which could be your organization name or abbreviation, e.g. 'eg' or 'cp'	`string`	`null`	no
placement	The placement specifications of the instances	object({ affinity = string availability_zone = string group_name = string host_id = string tenancy = string })	`null`	no
placement_group	The name of the placement group into which you'll launch your instances, if any	`string`	`""`	no
protect_from_scale_in	Allows setting instance protection. The autoscaling group will not select instances with this setting for terminination during scale in events	`bool`	`false`	no
regex_replace_chars	Regex to replace chars with empty string in `namespace`, `environment`, `stage` and `name`. If not set, `"/[^a-zA-Z0-9-]/"` is used to remove all characters other than hyphens, letters and digits.	`string`	`null`	no
scale_down_adjustment_type	Specifies whether the adjustment is an absolute number or a percentage of the current capacity. Valid values are `ChangeInCapacity`, `ExactCapacity` and `PercentChangeInCapacity`	`string`	`"ChangeInCapacity"`	no
scale_down_cooldown_seconds	The amount of time, in seconds, after a scaling activity completes and before the next scaling activity can start	`number`	`300`	no
scale_down_policy_type	The scaling policy type. Currently only `SimpleScaling` is supported	`string`	`"SimpleScaling"`	no
scale_down_scaling_adjustment	The number of instances by which to scale. `scale_down_scaling_adjustment` determines the interpretation of this number (e.g. as an absolute number or as a percentage of the existing Auto Scaling group size). A positive increment adds to the current capacity and a negative value removes from the current capacity	`number`	`-1`	no
scale_up_adjustment_type	Specifies whether the adjustment is an absolute number or a percentage of the current capacity. Valid values are `ChangeInCapacity`, `ExactCapacity` and `PercentChangeInCapacity`	`string`	`"ChangeInCapacity"`	no
scale_up_cooldown_seconds	The amount of time, in seconds, after a scaling activity completes and before the next scaling activity can start	`number`	`300`	no
scale_up_policy_type	The scaling policy type. Currently only `SimpleScaling` is supported	`string`	`"SimpleScaling"`	no
scale_up_scaling_adjustment	The number of instances by which to scale. `scale_up_adjustment_type` determines the interpretation of this number (e.g. as an absolute number or as a percentage of the existing Auto Scaling group size). A positive increment adds to the current capacity and a negative value removes from the current capacity	`number`	`1`	no
security_group_ids	A list of associated security group IDs	`list(string)`	`[]`	no
service_linked_role_arn	The ARN of the service-linked role that the ASG will use to call other AWS services	`string`	`""`	no
stage	Stage, e.g. 'prod', 'staging', 'dev', OR 'source', 'build', 'test', 'deploy', 'release'	`string`	`null`	no
subnet_ids	A list of subnet IDs to launch resources in	`list(string)`	n/a	yes
suspended_processes	A list of processes to suspend for the AutoScaling Group. The allowed values are `Launch`, `Terminate`, `HealthCheck`, `ReplaceUnhealthy`, `AZRebalance`, `AlarmNotification`, `ScheduledActions`, `AddToLoadBalancer`. Note that if you suspend either the `Launch` or `Terminate` process types, it can prevent your autoscaling group from functioning properly.	`list(string)`	`[]`	no
tag_specifications_resource_types	List of tag specification resource types to tag. Valid values are instance, volume, elastic-gpu and spot-instances-request.	`list(string)`	[ "instance", "volume" ]	no
tags	Additional tags (e.g. `map('BusinessUnit','XYZ')`	`map(string)`	`{}`	no
target_group_arns	A list of aws_alb_target_group ARNs, for use with Application Load Balancing	`list(string)`	`[]`	no
termination_policies	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`, `Default`	`list(string)`	[ "Default" ]	no
user_data_base64	The Base64-encoded user data to provide when launching the instances	`string`	`""`	no
wait_for_capacity_timeout	A maximum duration that Terraform should wait for ASG instances to be healthy before timing out. Setting this to '0' causes Terraform to skip all Capacity Waiting behavior	`string`	`"10m"`	no
wait_for_elb_capacity	Setting this will cause Terraform to wait for exactly this number of healthy instances in all attached load balancers on both create and update operations. Takes precedence over `min_elb_capacity` behavior	`number`	`0`	no

Outputs

Name	Description
autoscaling_group_arn	ARN of the AutoScaling Group
autoscaling_group_default_cooldown	Time between a scaling activity and the succeeding scaling activity
autoscaling_group_desired_capacity	The number of Amazon EC2 instances that should be running in the group
autoscaling_group_health_check_grace_period	Time after instance comes into service before checking health
autoscaling_group_health_check_type	`EC2` or `ELB`. Controls how health checking is done
autoscaling_group_id	The AutoScaling Group id
autoscaling_group_max_size	The maximum size of the autoscale group
autoscaling_group_min_size	The minimum size of the autoscale group
autoscaling_group_name	The AutoScaling Group name
autoscaling_group_tags	A list of tag settings associated with the AutoScaling Group
launch_template_arn	The ARN of the launch template
launch_template_id	The ID of the launch template

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Related Projects

Check out these related projects.

terraform-aws-ec2-instance - Terraform module for providing a general purpose EC2 instance
terraform-aws-ec2-bastion-server - Terraform module to define a generic bastion host with parameterized user data
terraform-aws-ec2-admin-server - Terraform module for providing an EC2 instance capable of running admin tasks
terraform-aws-ec2-instance-group - Terraform module for provisioning multiple general purpose EC2 hosts for stateful applications
terraform-aws-ec2-ami-snapshot - Terraform module to easily generate AMI snapshots to create replica instances

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License

See LICENSE for full details.

Licensed to the Apache Software Foundation (ASF) under one
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Contributors

Erik Osterman	Andriy Knysh	Igor Rodionov	RB

cdwbrad/terraform-aws-ec2-autoscale-group