Troubleshooting Python Flask App Deployment on Kubernetes

This article outlines the successful resolution of a misconfiguration issue that prevented a Python Flask application from being accessible on a Kubernetes cluster. The deployment, named python-deployment-nautilus, faced issues due to an incorrect image name and a misconfigured Service object. Initially, the application was inaccessible because the Deployment used the wrong image (poroko/flask-app-demo). This was corrected to poroko/flask-demo-appimage using the kubectl edit command. Additionally, the Service, python-service-nautilus, was set to NodePort 32345 but routed traffic to the incorrect container port (8080). The targetPort was updated to 5000, the default Flask port, ensuring proper routing. A validation check confirmed that the Service selector matched the Deployment’s labels (app: python_app), enabling correct traffic routing to the Pods. After these fixes, the application became fully operational and externally accessible via the specified NodePort. The article emphasizes the importance of verifying image names, port configurations, and selector labels in Kubernetes deployments to ensure seamless application functionality. This case study serves as a practical guide for DevOps professionals troubleshooting similar Kubernetes deployment issues.