Flask with Gunicorn in Minikube

This is a simple setup for running a Flask application with Gunicorn on Minikube and Docker.

Prerequisites

• Minikube installed and running.
• Docker installed.

Steps

1. Build the Docker image

   docker build -f docker/Dockerfile -t flask_on_k8s:latest .

   • After building the image, add it to Minikube's cache so it’s available for deployment:

   minikube image load flask_on_k8s:latest 

   • You can verify that the image is loaded with this command:

   minikube image list

   Note: Cached images will have the docker.io/library/ prefix.

2. Deploy to Minikube

   Apply the Kubernetes deployment and service:

   kubectl apply -f deployment/deployment.yml

   • Hint: Example for starting multiple nodes:

   minikube start --nodes 3 -p multinode-test

3. Access the Application

   Get the URL of the service:

   minikube service flask-test-app-service --url

   Open the URL in a browser or use curl to see the response.

4. Cleanup

   To delete the deployment and service, run:

   kubectl delete -f deployment/deployment.yml

Run Without Kubernetes

If you’d like to run the Docker container independently (outside Kubernetes) for testing, you can run it on a different external port (e.g., 9000).

Run container

• Detached mode

  docker run -d -p 9000:5000 --name=flask_with_gunicorn_localhost flask_on_k8s:latest

• Interactive mode

  docker run -it -p 9000:5000 --name=flask_with_gunicorn_localhost flask_on_k8s:latest sh

Useful commands

• Execute commands in container/pod

  kubectl exec -it <pod name> -- /bin/sh

• Restart deployment

  kubectl rollout restart deployment/flask-test-app-deployment

• Logs from container in deployment

  kubectl logs deployment/flask-test-app-deployment -c flask-test-app

Monitoring Setup

For detailed instructions on setting up and configuring the monitoring tools, check out the Monitoring Documentation.