In this article, we will see how to install kube-downscaler in Kubernetes cluster using Kubectl. If you are running your applications in a kubernetes cluster and wanted to save some cost of running workloads during less traffic hours or during off business hours when the load is very minimal then kube-downscaler is a must to use tool for this specific use cases. It can easily scale down the workloads (Deployments, StatefulSets, CronJobs, etc.) outside of business hours to save costs and can even scale back during normal business hours.

It is also very easy to use in your applications. You just have to deploy it in your cluster as a normal deployment and then start using its different annotations in your applications as per your requirement. While in our earlier article we have already seen a method to install it using kustomize and kubectl, here we will see even much simpler way to install by using just kubectl utility. So, let's begin. If you haven't seen the earlier article then check How to Install kube-downscaler in Kubernetes cluster using Kustomize and Kubectl 

 

How to install kube-downscaler in Kubernetes cluster using Kubectl

Also Read: How to trigger a cronjob manually in Kubernetes Cluster

Step 1: Prerequisites

a) You should have a running Kubernetes Cluster.

b) You should have kubectl and git installed and available to use.

c) You should have sudo or root access to run kubectl commands.

d) You should have access to kubernetes control node to run all the required commands.

 

Step 2: Clone git repo

You have to first clone the latest repo from official page by using git clone https://codeberg.org/hjacobs/kube-downscaler.git command as shown below. This will create a directory kube-downscaler in current working path and copy all contents in it.

cyberithub@cluster:~$ git clone https://codeberg.org/hjacobs/kube-downscaler.git
Cloning into 'kube-downscaler'...
remote: Enumerating objects: 1203, done.
remote: Counting objects: 100% (461/461), done.
remote: Compressing objects: 100% (131/131), done.
remote: Total 1203 (delta 429), reused 330 (delta 330), pack-reused 742 (from 1)
Receiving objects: 100% (1203/1203), 392.08 KiB | 427.00 KiB/s, done.
Resolving deltas: 100% (809/809), done.

 

Step 3: Remove kustomization.yaml file

Since the repo contents has kustomization.yaml file as well to support the working of kustomize tool, for kubectl it is not required. So we will just remove this file in order to install through just kubectl utility. To remove, you can simply use rm -rf kube-downscaler/deploy/kustomization.yaml command as shown below.

cyberithub@cluster:~$ rm -rf kube-downscaler/deploy/kustomization.yaml

 

Step 4: Install kube-downscaler

Now you can deploy all the required kubernetes objects from deploy directory in default namespace. To create or update existing objects, run kubectl apply -f kube-downscaler/deploy/ command as shown below. As you can see, all objects are successfully created.

cyberithub@cluster:~$ kubectl apply -f kube-downscaler/deploy/
configmap/kube-downscaler created
deployment.apps/kube-downscaler created
serviceaccount/kube-downscaler created
clusterrole.rbac.authorization.k8s.io/kube-downscaler created
clusterrolebinding.rbac.authorization.k8s.io/kube-downscaler created

 

Step 5: Verify Installation

After successful deployment, you can verify the installation status by running kubectl get all -n default command as shown below. This will list out all the kubernetes objects created under default namespace.

cyberithub@cluster:~$ kubectl get all -n default
NAME                                 READY STATUS   RESTARTS AGE
pod/kube-downscaler-bc8888bf4-phr8j  1/1   Running  0        6s

NAME                TYPE        CLUSTER-IP EXTERNAL-IP  PORT(S)  AGE
service/kubernetes  ClusterIP   10.96.0.1  <none>       443/TCP  3d18h

NAME                             READY  UP-TO-DATE  AVAILABLE  AGE
deployment.apps/kube-downscaler  1/1    1           1          6s

NAME                                       DESIRED  CURRENT  READY AGE
replicaset.apps/kube-downscaler-bc8888bf4  1        1        1     6s

 

Step 6: Scales down workload

To verify the usage of kube-downscaler, let's see a demo where we will scales down the replica of an application called cyberithub-app to 1 from original deployment replica of 2 on Saturday and Sunday from 1:00 AM to midnight (New York time). Outside of these hours, application deployment will run at full capacity of 2 replicas as shown below.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: cyberithub-app
  annotations:
    downscaler/downtime: "Sat-Sun 01:00-23:59 America/New_York"
    downscaler/downtime-replicas: "1"
spec:
  replicas: 2
  selector:
    matchLabels:
      app: cyberithub-app
  template:
    metadata:
      labels:
        app: cyberithub-app
    spec:
      containers:
      - name: cyberithub-container
        image: nginx:latest

 

Step 7: Delete all objects

Once you are done using kube-downscaler, you can also choose to remove entire deployed objects by using kubectl delete -f kube-downscaler/deploy/ command as shown below.

cyberithub@cluster:~$ kubectl delete -f kube-downscaler/deploy/
configmap "kube-downscaler" deleted
deployment.apps "kube-downscaler" deleted
serviceaccount "kube-downscaler" deleted
clusterrole.rbac.authorization.k8s.io "kube-downscaler" deleted
clusterrolebinding.rbac.authorization.k8s.io "kube-downscaler" deleted