How to automatically scale down a GKE node pool in the staging cluster to save money, with notifications via Slack.

Overview

This guide demonstrates how to implement an automated/manual solution for scaling down Kubernetes nodepools during off-hours while keeping your team informed through Slack notifications. This approach can significantly reduce cloud costs by ensuring compute resource aren't idle during non-business hours.

Prerequisites

• Kubernetes cluster (in post, I will use GKE)
• Slack workspace with permissions to create Webhooks
• KubeCTL access to your cluster
• ... ## Solution Components
  1. Golang CronJob to push notify yes/no scale up/down
  2. Slack notify and recieve message confirm from user
  3. Node Scale exc

Implement:

1. Create Slack bot and workspace

https://slack.com/help/articles/206845317-Create-a-Slack-workspace
https://programmingpercy.tech/blog/develop-a-slack-bot-using-golang/

2. Create GKE cluster and create node pool on it

https://cloud.google.com/kubernetes-engine/docs/deploy-app-cluster

3. Prepare k8s conf and bot

Prepare conf

• connect to cluster and get kube/congfig Check config

cat ~/.kube/config

• Code push message to Slack

type TypeQuestionType string

const (
    QuestionTypeYesNoScaleDown TypeQuestionType = "yes_no_scale_down"
    QuestionTypeYesNoScaleUp TypeQuestionType = "yes_no_scale_up"
)

func sendYesNoQuestion(client *slack.Client, channelID string, question string, typeQuestion TypeQuestionType) (string, error) {
    attachment := slack.Attachment{
        Text: question,
        CallbackID: string(typeQuestion),
        Actions: []slack.AttachmentAction{
            {
                Name: "yes",
                Text: "Yes",
                Type: "button",
                Value: "yes",
            },
            {
                Name: "no", 
                Text: "No",
                Type: "button",
                Value: "no",
            },
        },
    }
    _, timestamp, err := client.PostMessage(
        channelID,
        slack.MsgOptionAttachments(attachment),
    )
    if err != nil {
        return "", err
    }
    lastQuestionTimestamp = timestamp
    return "Response pending", nil
}

result test:

Flow chart

DEMO

https://www.youtube.com/watch?v=EybkQ9KJJbo
github: https://github.com/thanhphuchuynh/bot-slack-autoscale-gke