downscaler

README

k8s cluster downscaler

This project is a poor man's attempt to reduce cost with running clusters. The idea behind it is to automatically scale up/down the number of worker nodes. It is assumed that the clusters are used within certain time frames, thus not being needed outside them, e.g. evenings,weekends...etc

What is it?

The downscaler is a lambda function triggered at specific times. There are two available schedules to be set, one for upscaling and another for downscaling.

Build the downscaler

Run the following in the repository's root directory:

$ make

This will build the lambda source code under src/ and create a source.zip file.

Deploy the downscaler

The terraform code associated with the entire infra is found in the terraform directory.

Make sure you have the correct AWS credentials in place, fill in the variables as needed and proceed to apply.

Requirements

Name	Version
terraform	~> 1.1.5
aws	4.18.0

Providers

Name	Version
aws	4.18.0

Resources

Name	Type
aws_cloudwatch_event_rule.asg_down_scale_rule	resource
aws_cloudwatch_event_rule.asg_up_scale_rule	resource
aws_cloudwatch_event_target.asg_down_scale_target	resource
aws_cloudwatch_event_target.asg_up_scale_target	resource
aws_iam_policy.autoscaling_lifecycle_policy	resource
aws_iam_role.ec2_autoscaling_event_role	resource
aws_iam_role_policy_attachment.autoscaling_lifecycle_policy_attachment	resource
aws_iam_role_policy_attachment.cloud_watch_policy_attachment	resource
aws_lambda_function.asg_scale_function	resource
aws_lambda_permission.downscale_allow_cloudwatch	resource
aws_lambda_permission.upscale_allow_cloudwatch	resource
aws_autoscaling_groups.current_groups	data source
aws_iam_policy_document.instance_assume_role_policy	data source

Inputs

Name	Description	Type	Default	Required
cluster_name	Name of the cluster used for detecting the attached autoscaling-groups.	string	n/a	yes
lambda_file	Path to the zip file containing the lambda function. (see scaler.zip)	string	n/a	yes
scale_down_max_size	Max capacity after a scale down.	number	1	no
scale_down_schedule	Set the down scaling schedule. (expressed in UTC)	string	"cron(0 15 ? * MON-FRI *)"	no
scale_in_protection	Enable scale-in protection for new nodes after scale up.	bool	false	no
scale_up_max_size	Max capacity after a scale up.	number	10	no
scale_up_schedule	Set the up scaling schedule. (expressed in UTC)	string	"cron(0 6 ? * MON-FRI *)"	no