kubectl/k8s Cheat Sheet

 

• Namespaces
  • List all namespaces: kubectl get namespace
  • Set a namespace: kubens <namespace-name>
  • See currently set namespace: kubens -c
• Pods
  • List all pods: kubectl get pods
  • List all pods in specific namespace: kubectl get pods -n <namespace>
  • Kill a pod: kubectl delete pod <pod-name>
  • Describe/get details of pod: kubectl describe pods <pod-name>
  • InitContainers
    • Get logs: First describe the pod and look for the name of the init container. Then run kubectl logs <pod-name> -c <init-container-name>
• Deployments
  • Get the manifest for a deployment: kubectl get deploy <deployment-name> -o yaml
  • Scaling a deployment: kubectl scale --replicas=<n> deployment/<deployment-name>
  • Gen env vars defined on a pod: kubectl exec <pod> -- env
• ConfigMaps
  • View data in a ConfigMap: kubectl describe configmaps <name>

Accessing ConfigMap Data in Quarkus

Accessing ConfigMap Data in Quarkus

To retrieve configuration data from a Kubernetes ConfigMap in a Quarkus application, you can utilize the quarkus-kubernetes-config extension, which simplifies the integration of Kubernetes ConfigMaps and Secrets into your application. 
Here’s how you can do it:

Step 1: Add the Extension

First, ensure that you have the quarkus-kubernetes-config extension added to your Quarkus project. You can add it using the following command:

bash

./mvnw quarkus:add-extension -Dextensions="kubernetes-config"

Step 2: Create a ConfigMap

Create a ConfigMap in your Kubernetes cluster that contains the configuration properties you want to use. For example, you can create a ConfigMap named app-config with the following YAML:

yaml

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  greeting: "Hello, Quarkus!"
  port: "8080"

Apply this ConfigMap to your Kubernetes cluster:

bash

kubectl apply -f configmap.yaml

Step 3: Configure Quarkus to Use the ConfigMap

In your application.properties file, you can specify that Quarkus should read configuration values from the ConfigMap. For example:

properties

quarkus.kubernetes-config.config-map=app-config

Step 4: Access the Configuration in Your Application

You can access the values stored in the ConfigMap using the @ConfigProperty annotation in your Quarkus application. Here’s an example of how to do this:

java

import io.quarkus.arc.properties.UnlessBuildProfile;
import io.quarkus.runtime.Startup;
import org.eclipse.microprofile.config.inject.ConfigProperty;

import javax.enterprise.context.ApplicationScoped;

@ApplicationScoped
@Startup
public class GreetingService {

    @ConfigProperty(name = "greeting")
    String greeting;

    @ConfigProperty(name = "port")
    int port;

    public String getGreeting() {
        return greeting;
    }

    public int getPort() {
        return port;
    }
}

Conclusion

By following these steps, you can easily access configuration data from a Kubernetes ConfigMap in your Quarkus application. This approach allows you to manage your application's configuration dynamically, making it more adaptable to different environments without changing the codebase. The use of ConfigMaps enhances the flexibility and maintainability of your applications deployed on Kubernetes.