Keda cron scaler

README.md

@@ -114,7 +114,7 @@ Running various samples requires access to the Kyma runtime. There are also othe
 ## Advanced scenarios
 
 | Name                                                                                                                          | Description                                                                                                                              | References                                                                                                                                             |
-| ----------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------ |
+|-------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------|
 | [Redis and Kyma Functions](./redis-function/README.md)                                                                        | This sample provides a Redis deployment and two serverless functions that interact with it                                               | [Tutorial](https://developers.sap.com/tutorials/cp-kyma-redis-function.html)                                                                           |
 | [Cloud Integration Multi-cloud](./pi-scenario/README.md)                                                                      | This sample details how to bi-directionally connect SAP Process Integration and Kyma                                                     | -                                                                                                                                                      |
 | [Cloud Integration Neo](./pi-scenario/README-neo.md)                                                                          | This sample details how to bi-directionally connect SAP Process Integration and Kyma in NEO                                              | -                                                                                                                                                      |
@@ -123,10 +123,12 @@ Running various samples requires access to the Kyma runtime. There are also othe
 | [Next.js app with Kyma eventing & Go backend connected to SAP HANA Cloud database](./nextjs-app-with-kyma-eventing/README.md) | This sample provides a tutorial for a conference registration app using Next.js                                                          | [Post](https://blogs.sap.com/2022/02/24/going-jamstack-with-kyma-runtime-building-a-high-performance-web-app/)                                         |
 | [Data Backup and Restore](./data-backup-and-restore/README.md)                                                                | This sample demonstrates performing a backup and restore for a stateful application where data is stored using Persistence Volume Claim. | -                                                                                                                                                      |
 | [HandsOn DSAG Technology Days 2022](./dsagtt22/)                                                                              | This sample gives a walk-through setting up a scenario combining on prem systems with Kyma Functions and the Event Mesh                  | -                                                                                                                                                      |
-| [Query LDAP Users on on-premise](./sample-ldap/README.md)                                                                     | This sample queries the LDAP users from an on premise LDAP Server via SAP Connectivity proxy                  | -                                                                                                                                                      |
-| [Deploy Highly Available Workloads](./multi-zone-ha-deployment/README.md)                                                                     | This sample demonstrates deploying highly available workloads in Kyma runtime                  | -                                                                                                                                                      |
-| [Power of serverless with SAP BTP, Kyma runtime.](./kyma-serverless/README.md)                                                                     | This sample demonstrates how to leverage latest features of kyma functions with SAP HANA Cloud and SAP libraries                  | [Post](https://blogs.sap.com/2023/02/06/power-of-serverless-with-sap-btp-kyma-runtime.-secrets-mounted-as-volumes./)                                                                                                                                                   |
-| [Using the on-premise Docker registry with Kyma runtime](./on-premise-docker-registry/README.md) | This sample demonstrates how to pull images from the on-premise Docker registry for applications deployed on Kyma runtime | -  |
+| [Query LDAP Users on on-premise](./sample-ldap/README.md)                                                                     | This sample queries the LDAP users from an on premise LDAP Server via SAP Connectivity proxy                                             | -                                                                                                                                                      |
+| [Deploy Highly Available Workloads](./multi-zone-ha-deployment/README.md)                                                     | This sample demonstrates deploying highly available workloads in Kyma runtime                                                            | -                                                                                                                                                      |
+| [Power of serverless with SAP BTP, Kyma runtime.](./kyma-serverless/README.md)                                                | This sample demonstrates how to leverage latest features of kyma functions with SAP HANA Cloud and SAP libraries                         | [Post](https://blogs.sap.com/2023/02/06/power-of-serverless-with-sap-btp-kyma-runtime.-secrets-mounted-as-volumes./)                                   |
+| [Using the on-premise Docker registry with Kyma runtime](./on-premise-docker-registry/README.md)                              | This sample demonstrates how to pull images from the on-premise Docker registry for applications deployed on Kyma runtime                | -                                                                                                                                                      |
+| [KEDA Cron based scaler](./keda-cron-scaler/README.md)                                                                        | This sample demonstrates how to leverage KEDA Cron scaler for efficient scaling strategies.                                              | -                                                                                                                                                      |
+
 
 ## Multitenancy and SaaS
 

keda-cron-scaler/README.md

@@ -0,0 +1,149 @@
+# SAP BTP Kyma Runtime: Leveraging KEDA module capabilities for efficient and cost-effective scaling
+
+SAP Business Technology Platform (BTP) Kyma runtime is currently in the process of undergoing a pivotal change as it transitions to a modular architecture. This transformation will provide customers with the advantage of a la carte selection of components or capabilities, thereby reducing unnecessary overhead and complexity. One of the first modules to emerge within this novel framework is KEDA (Kubernetes Event-driven Autoscaling).
+
+## Introduction to KEDA
+
+[KEDA](https://keda.sh/), an open-source initiative that facilitates event-driven autoscaling for Kubernetes workloads, was originally developed by Microsoft and Red Hat. It has since become a sandbox project under the Cloud Native Computing Foundation (CNCF). KEDA focuses on autoscaling applications in response to events sourced from a variety of platforms, including Kafka, RabbitMQ, and cloud-specific services such as Azure Service Bus and Google Pub/Sub.
+
+## The Benefits of KEDA
+
+KEDA ushers in a new era of flexibility and efficiency in autoscaling. It enhances Kubernetes' capacity to support fine-grained autoscaling for event-driven workloads. Leveraging KEDA, you can dynamically scale your deployments from zero to any arbitrary number, contingent on the volume of events they are designed to process.
+
+## Activating the KEDA Module in SAP BTP Kyma Runtime
+
+You can activate KEDA like any other module by adhering to the official guidelines on how to [enable and disable a module](https://help.sap.com/docs/btp/sap-business-technology-platform/enable-and-disable-kyma-module).
+
+## KEDA's Cron-Based Scaler
+
+KEDA offers a broad range of scaling strategies, one of which is the **cron-based scaler**. This scaler allows you to schedule scaling actions according to the time of day, an invaluable feature for managing predictable fluctuations in workload.
+
+As an illustration, the cron-based scaler enables you to:
+
+- **Manage High Traffic and Request Volume Peaks**: With the cron-based scaler, you can program your applications to upscale during peak hours or during high-traffic events, such as Black Friday or New Year sales. The same functionality can be used to schedule your applications to upscale during off-peak hours for batch processing tasks.
+
+![bf](assets/keda-scale-bf.png)
+
+- **Optimize Resource Utilization and Reduce Expenses**: The cron-based scaler offers a solution to optimize resource utilization and reduce costs by allowing you to schedule your applications to downscale during non-working hours. This feature is useful for your **dev/stage/QA** clusters, which are not required during off-working hours.
+
+  > **Note:** This only benefits when your workloads require more resources than the base setup. The [current base setup](https://kyma-project.github.io/price-calculator/) consists of 3 VMs, each with 4 CPU and 16 GB of RAM. Therefore, *if you your workloads need 4 or more VMs to be provisioned, this feature can provide benefits to control costs during off-work hours.*
+
+![off-work](assets/keda-scale-off-work.png)
+
+## Scenario
+
+Lets put cron based scaler to action.
+
+Assume we have a **development cluster** where we want to run workloads only during work hours.
+
+Lets say **Monday - Friday, 8 AM to 6 PM**
+
+### Prerequisites
+
+- [SAP BTP, Kyma runtime instance](../prerequisites/#kyma)
+- [Kubernetes tooling](../prerequisites/#kubernetes)
+- [KEDA and Serverless Modules enabled in Kyma]((https://help.sap.com/docs/btp/sap-business-technology-platform/enable-and-disable-kyma-module))
+
+### Steps
+
+- Export environment variables
+
+```shell
+export NS={your-namespace}
+```
+
+- Create namespace and enable istio injection if not already done
+
+```shell
+kubectl create ns ${NS}
+# only required once to enable istio sidecar. Ignore if done already
+kubectl label namespaces ${NS} istio-injection=enabled
+```
+
+- Create sample workloads. One deployment and one function
+
+```shell
+kubectl -n ${NS} apply -f k8s/deployment.yaml
+kubectl -n ${NS} apply -f k8s/function.yaml
+```
+
+- Apply the KEDA cron based scaling to these workloads
+
+```shell
+kubectl -n ${NS} apply -f k8s/keda-cron-scaler.yaml
+```
+
+### How it works
+
+KEDA `scaledobject` resource can be configured with a trigger of type cron.
+
+In the cron scaler, we can then specify to have the workloads running only during the working hours.
+
+```yaml
+  triggers:
+    - type: cron
+      metadata:
+        # The acceptable values would be a value from the IANA Time Zone Database.
+        timezone: Europe/Berlin  
+        # At 08:00 AM, Monday through Friday
+        start: 0 8 * * 1-5
+        # At 06:00 PM, Monday through Friday
+        end: 0 18 * * 1-5
+        # ie. Your MINIMUM replica count for this workload
+        desiredReplicas: "1"
+```
+
+For each type of workload, the **scaleTargetRef** need to be specified
+
+```yaml
+spec:
+  scaleTargetRef:
+    apiVersion: apps/v1
+    kind: Deployment
+    name: test-keda-cron-nginx
+```
+
+```yaml
+spec:
+  scaleTargetRef:
+    apiVersion: serverless.kyma-project.io/v1alpha2
+    kind: Function
+    name: test-keda-cron-function
+```
+
+### View the events
+
+Check the events during the trigger start or end time. Here you can see KEDA scaling down the replicas
+
+```shell
+kubectl -n ${NS} get events
+```
+
+```shell
+LAST SEEN   TYPE      REASON                       OBJECT                                       MESSAGE
+7m34s       Normal    Killing                      pod/test-keda-cron-nginx-86b78b79df-r42zd    Stopping container istio-proxy
+7m34s       Normal    Killing                      pod/test-keda-cron-nginx-86b78b79df-r42zd    Stopping container nginx
+7m31s       Warning   Unhealthy                    pod/test-keda-cron-nginx-86b78b79df-r42zd    Readiness probe failed: HTTP probe failed with statuscode: 503
+7m34s       Normal    SuccessfulDelete             replicaset/test-keda-cron-nginx-86b78b79df   Deleted pod: test-keda-cron-nginx-86b78b79df-r42zd
+7m34s       Normal    KEDAScaleTargetDeactivated   scaledobject/test-keda-cron-nginx            Deactivated apps/v1.Deployment demos/test-keda-cron-nginx from 1 to 0
+7m34s       Normal    ScalingReplicaSet            deployment/test-keda-cron-nginx              Scaled down replica set test-keda-cron-nginx-86b78b79df to 0 from 1
+```
+
+> Note: Events are only available until after 1 hour of trigger.
+
+### First hand experience
+
+I applied the KEDA cron scaler to all my custom workloads in my Kyma cluster.
+
+All my deployment replicas scaled down to zero
+
+![dep-off](assets/keda-off-hours.png)
+
+and number of nodes (VMs) reduced from 4 to 3
+
+![nodes-off](assets/nodes-off-hours.png)
+
+## References
+
+- <https://medium.com/@CloudifyOps/optimizing-kubernetes-workloads-with-keda-custom-metric-driven-pod-autoscaling-7332e674fdc6>
+- <https://doc.kaas.thalesdigital.io/docs/Features/keda>

keda-cron-scaler/k8s/deployment.yaml

@@ -0,0 +1,24 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  creationTimestamp: null
+  labels:
+    app: test-keda-cron-nginx
+  name: test-keda-cron-nginx
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: test-keda-cron-nginx
+  strategy: {}
+  template:
+    metadata:
+      creationTimestamp: null
+      labels:
+        app: test-keda-cron-nginx
+    spec:
+      containers:
+      - image: nginx
+        name: nginx
+        resources: {}
+status: {}

keda-cron-scaler/k8s/function.yaml

@@ -0,0 +1,19 @@
+apiVersion: serverless.kyma-project.io/v1alpha2
+kind: Function
+metadata:
+  name: test-keda-cron-function
+  labels:
+    app: test-keda-cron-function
+spec:
+  runtime: nodejs18
+  source:
+    inline:
+      source: |
+        module.exports = {
+          main: function(event, context) {
+            console.log('I only run during work hours!!');
+          }
+        }
+  scaleConfig:
+    minReplicas: 1
+    maxReplicas: 1

keda-cron-scaler/k8s/keda-cron-scaler.yaml

@@ -0,0 +1,51 @@
+apiVersion: keda.sh/v1alpha1
+kind: ScaledObject
+metadata:
+  name: test-keda-cron-nginx
+spec:
+  scaleTargetRef:
+    apiVersion: apps/v1
+    kind: Deployment
+    name: test-keda-cron-nginx
+  pollingInterval: 10
+  # immediately scale down the workload
+  cooldownPeriod: 0
+  # The workload is ASLEEP by DEFAULT, otherwise, it's Awake.
+  minReplicaCount: 0
+  triggers:
+    - type: cron
+      metadata:
+        # The acceptable values would be a value from the IANA Time Zone Database.
+        timezone: Europe/Berlin  
+        # At 08:00 AM, Monday through Friday
+        start: 0 8 * * 1-5
+        # At 06:00 PM, Monday through Friday
+        end: 0 18 * * 1-5
+        # ie. Your MINIMUM replica count for this workload
+        desiredReplicas: "1"
+---
+apiVersion: keda.sh/v1alpha1
+kind: ScaledObject
+metadata:
+  name: test-keda-cron-function
+spec:
+  scaleTargetRef:
+    apiVersion: serverless.kyma-project.io/v1alpha2
+    kind: Function
+    name: test-keda-cron-function
+  pollingInterval: 10
+  # immediately scale down the workload
+  cooldownPeriod: 0
+  # The workload is ASLEEP by DEFAULT, otherwise, it's Awake.
+  minReplicaCount: 0
+  triggers:
+    - type: cron
+      metadata:
+        # The acceptable values would be a value from the IANA Time Zone Database.
+        timezone: Europe/Berlin  
+        # At 08:00 AM, Monday through Friday
+        start: 0 8 * * 1-5
+        # At 06:00 PM, Monday through Friday
+        end: 0 18 * * 1-5
+        # ie. Your MINIMUM replica count for this workload
+        desiredReplicas: "1"