Custom VM Autoscaler

It is a CLI that manages the scaling of virtual machines when certain conditions are met and executes some tasks prior to deleting the virtual machine in question.

Motivation

In several use cases, solutions are deployed directly on virtual machines without using solutions like Kubernetes, and there is a need to scale and unscale these virtual machines just as one would with Kubernetes nodes or pods.

However, the solutions available on the market are quite limited in terms of checks, script executions, etc. This is where custom-vm-autoscaler comes in.

This solution is responsible for checking metrics from any supported market solution (Prometheus, Mimir, etc.) and, depending on whether a condition is met, creates or destroys virtual machines. Before destroying a virtual machine, X operations are performed (currently, for example, it fully drains the node with Elasticsearch).

This solution is open to any compatibility, and we encourage the community to develop them!

Flags

As every configuration parameter can be defined in the config file, there are only few flags that can be defined. They are described in the following table:

Name	Description	Default	Example
--config	Define the path to the config file	autoscaler.yaml	--config ./autoscaler.yaml

Environment variables

Some parameters can be defined not only by fixing them into the configuration file, but setting them as environment variables. This is mostly used by credentials as a safer way to work with containers:

Environment variables take precedence over configuration

Name	Description	Default
ELASTICSEARCH_USERNAME	Define the username for basic auth on elasticsearch integration	empty
ELASTICSEARCH_PASSWORD	Define the password for basic auth on elasticsearch integration	empty

Examples

Here you have a complete example. More up-to-date one will always be maintained in config/samples directory here

---
# Metrics service to check conditions for scaling up or down the cluster
metrics:

  # Prometheus integration
  prometheus:
    url: "http://127.0.0.1:8080"
    upCondition: "placeholder"
    downCondition: "placeholder"
    headers: {}

# Infrastructure service to interact with the cloud provider (GCP, AWS, etc.)
infrastructure:

  # GCP integration
  gcp:
    projectId: "placeholder"
    zone: "placeholder"
    migName: "placeholder"
    credentials_file: "placeholder"

# Target to control when scaling down the cluster
target:

  # Elasticsearch target service
  elasticsearch:
    url: "https://localhost:9200"
    user: "${ELASTICSEARCH_USER}"
    password: "${ELASTICSEARCH_PASSWORD}"
    sslInsecureSkipVerify: true

# Notifications service to send alerts to the team
notifications:

  # Slack integration
  slack:
    webhookUrl: "placeholder"

# General configuration for the autoscaler
autoscaler:
  debugMode: true
  defaultCooldownPeriodSec: 10
  scaledownCooldownPeriodSec: 10
  retiryIntervalSec: 10
  minSize: 1
  maxSize: 2
  scaleUpThreshold: 1

  # For advanced custom scaling configuration, when you want a different minSize and maxSize nodes for specific moments
  advancedCustomScalingConfiguration:
    - days: "2,3,4"
      hoursUTC: "5:00:00-8:00:00"
      minSize: 1
      scaleUpThreshold: 2
    - days: "6,7"
      minSize: 3

ATTENTION: If you detect some mistake on the config, open an issue to fix it. This way we all will benefit

How to deploy

This project provides binary files and Docker images to make it easy to be deployed wherever wanted

Binaries

Binary files for most popular platforms will be added to the releases

Docker

Docker images can be found in GitHub's packages related to this repository

Do you need it in a different container registry? I think this is not needed, but if I'm wrong, please, let's discuss it in the best place for that: an issue

How to contribute

We are open to external collaborations for this project: improvements, bugfixes, whatever.

For doing it, open an issue to discuss the need of the changes, then:

• Fork the repository
• Make your changes to the code
• Open a PR and wait for review

The code will be reviewed and tested (always)

We are developers and hate bad code. For that reason we ask you the highest quality on each line of code to improve this project on each iteration.