Configuring Resource Requests/Limits in Kubernetes

1. Introduction

This lesson covers the configuration of resource requests and limits in Kubernetes, which are essential for resource management and optimization within a cluster.

2. Key Concepts

2.1 Resource Requests

Resource requests define the minimum amount of CPU and memory that a container requires. Kubernetes uses these values for scheduling decisions.

2.2 Resource Limits

Resource limits set the maximum amount of CPU and memory that a container can use. Exceeding these limits can result in throttling or termination of the container.

Note: Properly configuring resource requests and limits is crucial for optimizing resource utilization and ensuring application stability.

3. Configuration Steps

Define Resource Requests and Limits:

Specify the desired values in your deployment YAML file.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 2
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
      - name: my-container
        image: my-image:latest
        resources:
          requests:
            memory: "64Mi"
            cpu: "250m"
          limits:
            memory: "128Mi"
            cpu: "500m"

Apply the Configuration:
Use the following command to apply the changes.
```
kubectl apply -f my-deployment.yaml
```
Verify the Configuration:
Check the resource allocation using:
```
kubectl describe deployment my-app
```

4. Best Practices

Always set resource requests to ensure that Pods have the resources they need to function properly.
Set limits to prevent any single container from consuming excessive resources.
Monitor resource usage to adjust requests and limits as necessary based on actual usage patterns.
Use vertical pod autoscaler (VPA) for automatic adjustment of requests and limits based on observed usage.

5. FAQ

What happens if a container exceeds its resource limit?

If a container exceeds its resource limit, Kubernetes may throttle the container, leading to degraded performance, or it may terminate the container depending on the resource type.

Can I set requests and limits for all containers in a namespace?

Yes, you can use LimitRanges to set default requests and limits for all containers in a namespace.

How can I check the current resource usage of my Pods?

You can use the command kubectl top pods to check the current resource usage of your Pods.