feat(autoscaling): terminate instances instead of stopping them

Previously, when instances were stopped, they remained in a suspended state, incurring unnecessary costs and resource usage. This commit introduces the functionality to terminate instances directly, ensuring efficient resource management and cost optimization.

When the autoscaling will be resume, instances will be recreated by
the autoscaling service.

examples/autoscaling-scheduler-terminate-instances/main.tf

@@ -25,8 +25,8 @@ resource "aws_subnet" "this" {
   cidr_block = "10.0.1.0/24"
 }
 
-resource "aws_launch_configuration" "this" {
-  name          = "web_config"
+resource "aws_launch_template" "this" {
+  name_prefix   = "web_config"
   image_id      = data.aws_ami.ubuntu.id
   instance_type = "t2.micro"
 }
@@ -41,8 +41,19 @@ resource "aws_autoscaling_group" "scheduled" {
   health_check_type         = "EC2"
   desired_capacity          = 1
   force_delete              = true
-  launch_configuration      = aws_launch_configuration.this.name
   vpc_zone_identifier       = [aws_subnet.this.id]
+  mixed_instances_policy {
+    instances_distribution {
+      on_demand_base_capacity                  = 0
+      on_demand_percentage_above_base_capacity = 25
+      spot_allocation_strategy                 = "capacity-optimized"
+    }
+    launch_template {
+      launch_template_specification {
+        launch_template_id = aws_launch_template.this.id
+      }
+    }
+  }
 
   tag {
     key                 = "tostop"
@@ -66,8 +77,19 @@ resource "aws_autoscaling_group" "not_scheduled" {
   health_check_type         = "EC2"
   desired_capacity          = 1
   force_delete              = true
-  launch_configuration      = aws_launch_configuration.this.name
   vpc_zone_identifier       = [aws_subnet.this.id]
+  mixed_instances_policy {
+    instances_distribution {
+      on_demand_base_capacity                  = 0
+      on_demand_percentage_above_base_capacity = 25
+      spot_allocation_strategy                 = "capacity-optimized"
+    }
+    launch_template {
+      launch_template_specification {
+        launch_template_id = aws_launch_template.this.id
+      }
+    }
+  }
 
   tag {
     key                 = "tostop"

main.tf

@@ -270,17 +270,18 @@ resource "aws_lambda_function" "this" {
 
   environment {
     variables = {
-      AWS_REGIONS               = var.aws_regions == null ? data.aws_region.current.name : join(", ", var.aws_regions)
-      SCHEDULE_ACTION           = var.schedule_action
-      TAG_KEY                   = local.scheduler_tag["key"]
-      TAG_VALUE                 = local.scheduler_tag["value"]
-      DOCUMENTDB_SCHEDULE       = tostring(var.documentdb_schedule)
-      EC2_SCHEDULE              = tostring(var.ec2_schedule)
-      ECS_SCHEDULE              = tostring(var.ecs_schedule)
-      RDS_SCHEDULE              = tostring(var.rds_schedule)
-      REDSHIFT_SCHEDULE         = tostring(var.redshift_schedule)
-      AUTOSCALING_SCHEDULE      = tostring(var.autoscaling_schedule)
-      CLOUDWATCH_ALARM_SCHEDULE = tostring(var.cloudwatch_alarm_schedule)
+      AWS_REGIONS                     = var.aws_regions == null ? data.aws_region.current.name : join(", ", var.aws_regions)
+      SCHEDULE_ACTION                 = var.schedule_action
+      TAG_KEY                         = local.scheduler_tag["key"]
+      TAG_VALUE                       = local.scheduler_tag["value"]
+      DOCUMENTDB_SCHEDULE             = tostring(var.documentdb_schedule)
+      EC2_SCHEDULE                    = tostring(var.ec2_schedule)
+      ECS_SCHEDULE                    = tostring(var.ecs_schedule)
+      RDS_SCHEDULE                    = tostring(var.rds_schedule)
+      REDSHIFT_SCHEDULE               = tostring(var.redshift_schedule)
+      AUTOSCALING_SCHEDULE            = tostring(var.autoscaling_schedule)
+      AUTOSCALING_TERMINATE_INSTANCES = tostring(var.autoscaling_terminate_instances)
+      CLOUDWATCH_ALARM_SCHEDULE       = tostring(var.cloudwatch_alarm_schedule)
     }
   }
 

package/scheduler/autoscaling_handler.py

@@ -25,7 +25,7 @@ def __init__(self, region_name=None) -> None:
             self.asg = boto3.client("autoscaling")
         self.waiter = AwsWaiters(region_name=region_name)
 
-    def stop(self, aws_tags: List[Dict]) -> None:
+    def stop(self, aws_tags: List[Dict], terminate_instances=False) -> None:
         """Aws autoscaling suspend function.
 
         Suspend autoscaling group and stop its instances
@@ -42,6 +42,8 @@ def stop(self, aws_tags: List[Dict]) -> None:
                     ]
                 }
             ]
+        :param bool terminate_instances:
+            Terminate autoscaling instances if True
         """
         tag_key = aws_tags[0]["Key"]
         tag_value = "".join(aws_tags[0]["Values"])
@@ -55,11 +57,15 @@ def stop(self, aws_tags: List[Dict]) -> None:
             except ClientError as exc:
                 ec2_exception("instance", asg_name, exc)
 
-        # Stop autoscaling instance
+        # Stop or Terminate autoscaling instances
         for instance_id in instance_id_list:
             try:
-                self.ec2.stop_instances(InstanceIds=[instance_id])
-                print(f"Stop autoscaling instances {instance_id}")
+                if terminate_instances:
+                    self.ec2.terminate_instances(InstanceIds=[instance_id])
+                    print(f"Terminate autoscaling instances {instance_id}")
+                else:
+                    self.ec2.stop_instances(InstanceIds=[instance_id])
+                    print(f"Stop autoscaling instances {instance_id}")
             except ClientError as exc:
                 ec2_exception("autoscaling group", instance_id, exc)
 

package/scheduler/main.py

@@ -32,18 +32,27 @@ def lambda_handler(event, context):
     schedule_action = os.getenv("SCHEDULE_ACTION")
     aws_regions = os.getenv("AWS_REGIONS").replace(" ", "").split(",")
     format_tags = [{"Key": os.getenv("TAG_KEY"), "Values": [os.getenv("TAG_VALUE")]}]
-
-    _strategy = {}
-    _strategy[AutoscalingScheduler] = os.getenv("AUTOSCALING_SCHEDULE")
-    _strategy[DocumentDBScheduler] = os.getenv("DOCUMENTDB_SCHEDULE")
-    _strategy[InstanceScheduler] = os.getenv("EC2_SCHEDULE")
-    _strategy[EcsScheduler] = os.getenv("ECS_SCHEDULE")
-    _strategy[RdsScheduler] = os.getenv("RDS_SCHEDULE")
-    _strategy[RedshiftScheduler] = os.getenv("REDSHIFT_SCHEDULE")
-    _strategy[CloudWatchAlarmScheduler] = os.getenv("CLOUDWATCH_ALARM_SCHEDULE")
+    autoscaling_terminate_instances = strtobool(
+        os.getenv("AUTOSCALING_TERMINATE_INSTANCES")
+    )
+
+    _strategy = {
+        AutoscalingScheduler: os.getenv("AUTOSCALING_SCHEDULE"),
+        DocumentDBScheduler: os.getenv("DOCUMENTDB_SCHEDULE"),
+        InstanceScheduler: os.getenv("EC2_SCHEDULE"),
+        EcsScheduler: os.getenv("ECS_SCHEDULE"),
+        RdsScheduler: os.getenv("RDS_SCHEDULE"),
+        RedshiftScheduler: os.getenv("REDSHIFT_SCHEDULE"),
+        CloudWatchAlarmScheduler: os.getenv("CLOUDWATCH_ALARM_SCHEDULE"),
+    }
 
     for service, to_schedule in _strategy.items():
         if strtobool(to_schedule):
             for aws_region in aws_regions:
                 strategy = service(aws_region)
-                getattr(strategy, schedule_action)(aws_tags=format_tags)
+                if service == AutoscalingScheduler and autoscaling_terminate_instances:
+                    getattr(strategy, schedule_action)(
+                        aws_tags=format_tags, terminate_instances=True
+                    )
+                else:
+                    getattr(strategy, schedule_action)(aws_tags=format_tags)

variables.tf

@@ -61,6 +61,12 @@ variable "autoscaling_schedule" {
   default     = false
 }
 
+variable "autoscaling_terminate_instances" {
+  description = "Terminate instances when autoscaling group is scheduled to stop"
+  type        = bool
+  default     = false
+}
+
 variable "ec2_schedule" {
   description = "Enable scheduling on ec2 resources"
   type        = any