How to Exclude Specific Containers' Metrics in Kubernetes Horizontal Pod Autoscaling

How to Exclude Specific Containers' Metrics in Kubernetes Horizontal Pod Autoscaling

Kubernetes, the open-source platform for automating deployment, scaling, and management of containerized applications, has become a staple in the world of DevOps and data science. One of its powerful features is the Horizontal Pod Autoscaler (HPA), which automatically scales the number of pods in a replication controller, deployment, replica set, or stateful set based on observed CPU utilization. However, there may be instances where you want to exclude certain containers' metrics from this autoscaling process. This blog post will guide you on how to achieve this.

Prerequisites

Before we dive in, ensure you have the following:

• A working Kubernetes cluster
• kubectl installed and configured
• Basic understanding of Kubernetes and HPA

Understanding Kubernetes HPA

Kubernetes HPA adjusts the number of pod replicas in a Kubernetes Replication Controller, Deployment, or Replica Set. It does this based on the CPU utilization or custom metrics. However, in some scenarios, you might want to exclude specific containers' metrics from the autoscaling process. This could be due to reasons such as:

• The container is running a sidecar or helper process that should not influence scaling.
• The container is running a batch job or a short-lived task that should not affect the overall pod scaling.

How to Exclude Containers' Metrics

To exclude specific containers' metrics from the HPA, you need to modify the HPA configuration. Here’s a step-by-step guide on how to do this:

Step 1: Identify the Containers

First, identify the containers whose metrics you want to exclude. You can do this by running the following command:

kubectl get pods -o jsonpath='{.items[*].spec.containers[*].name}'

This command will list all the containers running in your Kubernetes cluster.

Step 2: Modify the HPA Configuration

Next, modify the HPA configuration to exclude the identified containers. You can do this by adding an annotation to the HPA configuration. The annotation should be in the format autoscaling.alpha.kubernetes.io/exclude-containers: "container1,container2".

Here’s an example of how to add the annotation:

apiVersion: autoscaling/v2beta2
kind: HorizontalPodAutoscaler
metadata:
  name: my-hpa
  annotations:
    autoscaling.alpha.kubernetes.io/exclude-containers: "container1,container2"
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: my-deployment
  minReplicas: 1
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 50

In this example, the HPA named my-hpa will exclude the metrics from container1 and container2 when performing autoscaling.

Step 3: Apply the Changes

Finally, apply the changes to the HPA configuration by running the following command:

kubectl apply -f my-hpa.yaml

This command will update the HPA configuration with the new settings.

Conclusion

Kubernetes HPA is a powerful feature that allows for automatic scaling of pods based on CPU utilization or custom metrics. However, there may be instances where you want to exclude certain containers' metrics from this process. By following the steps outlined in this blog post, you can easily achieve this.

Remember, Kubernetes is a complex system, and it’s essential to understand the implications of your changes. Always test your changes in a controlled environment before applying them to your production systems.

Stay tuned for more Kubernetes tips and tricks!

Keywords: Kubernetes, Horizontal Pod Autoscaler, HPA, Exclude Containers, Metrics, Autoscaling, DevOps, Data Science, Kubernetes Cluster, kubectl, Replication Controller, Deployment, Replica Set, CPU Utilization, Custom Metrics, Annotation, Configuration

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