Managing Auto Scaling Group via terraform

Question

Let say I have a auto-scaling group which I manage via terraform. And i want that auto scaling group to scale up and scale down based on our business hours .

The TF template for managing ASG :

resource "aws_autoscaling_group" "foobar" {
  availability_zones        = ["us-west-2a"]
  name                      = "terraform-test-foobar5"
  max_size                  = 1
  min_size                  = 1
  health_check_grace_period = 300
  health_check_type         = "ELB"
  force_delete              = true
  termination_policies      = ["OldestInstance"]
}

resource "aws_autoscaling_schedule" "foobar" {
  scheduled_action_name  = "foobar"
  min_size               = 0
  max_size               = 1
  desired_capacity       = 0
  start_time             = "2016-12-11T18:00:00Z"
  end_time               = "2016-12-12T06:00:00Z"
  autoscaling_group_name = aws_autoscaling_group.foobar.name
}

As we can see here i have to set a particular date and time for the action.

what I want is : I want to scale down on saturday night 9 pm by 10% of my current capacity, and then again want to scale up by 10% on monday morning 6 am .

How can I achieve this.

Any help is highly appreciated. Please let me know how to get through this.

Is there more complexity here that you haven't shown? Right now you have a very static ASG and then you change it at a specific time. If you don't also attach autoscaling policies to the ASG to scale the number of instances then there's nothing wrong with your above code (although I assume it would be you have eg 10 instances during the week and then scale down to 9 during the weekend). If there is more complexity than that then you should explain so in the question and ideally show the minimal code required to have that scaling. — ydaetskcoR, Apr 22 '21 at 08:07
I have created a new post with the detailed code I am using , and what i want to achieve. Here is the link. : https://stackoverflow.com/questions/67212282/manage-asg-via-terraform. Please refer to this and help — Legitimate_Figure_4430, Apr 22 '21 at 11:25

score 1 · Accepted Answer · answered Apr 22 '21 at 07:41

1

The solution is not straightforward, but is doable. The required steps are:

create a Lambda function that scales down the ASG (e.g. with Boto3 and Python)
assign an IAM role with the right permissions
create a Cron trigger for "every saturday 9pm" with aws_cloudwatch_event_rule
create a aws_cloudwatch_event_target, with the previously created Cron trigger and Lambda function
repeat for scaling up

This module will probably fit your needs, you just have to code the Lambda and use the module to trigger it on a schedule.

answered Apr 22 '21 at 07:41

Simone Ripamonti

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1
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I have created a new post with the detailed code I am using , and what i want to achieve. Here is the link. : stackoverflow.com/questions/67212282/manage-asg-via-terraform. Please refer to this and help. thanks for your help on this 1 – Legitimate_Figure_4430 Apr 22 '21 at 12:22
Why would you need a Lambda function for this, when AWS already has time-based auto scaling? https://docs.aws.amazon.com/autoscaling/ec2/userguide/schedule_time.html – Mark B Apr 22 '21 at 15:55

Managing Auto Scaling Group via terraform

1 Answers1