How Kubernetes Works Under the Hood with Docker Desktop

If you are a developer or DevOps engineer, you have likely heard of Kubernetes and Docker Desktop. Both tools are widely used in modern software development but how do they work together under the hood? Understanding their integration helps you manage containerized applications efficiently. In this article, we will break down how Kubernetes operates within Docker Desktop, offering an interactive and easy-to-follow explanation.

What is Kubernetes?

Kubernetes, often abbreviated as K8s, is an open-source container orchestration platform. It automates the deployment, scaling and management of containerized applications. Originally developed by Google, Kubernetes has become the de facto standard for container orchestration.

What is Docker Desktop?

Docker Desktop is a platform that allows developers to build, share, and run containerized applications. It provides an easy-to-use interface for managing Docker containers and includes an option to enable Kubernetes.

Docker Desktop simplifies Kubernetes management by bundling everything you need into a single package. This is particularly useful for local development and testing before deploying applications to a production Kubernetes cluster.

Enabling Kubernetes in Docker Desktop

To use Kubernetes with Docker Desktop, you first need to enable it:

1. Open Docker Desktop.

2. Navigate to Settings.

3. Select the Kubernetes tab.

4. Check the Enable Kubernetes option.

5. Click Apply & Restart.

Once enabled, Docker Desktop installs a lightweight Kubernetes cluster on your machine, making it easy to test Kubernetes configurations locally.

How Kubernetes Works Under the Hood with Docker Desktop

1. Docker as the Container Runtime

Kubernetes needs a container runtime to run applications, and in the case of Docker Desktop, it uses Docker Engine. The workflow looks like this:

• Kubernetes schedules a Pod, which is the smallest deployable unit.

• Inside each Pod, one or more containers run the actual application.

• Kubernetes interacts with the Docker Engine to pull images, create containers, and manage their lifecycle.

  
  

2. Kubernetes Components in Docker Desktop

When you enable Kubernetes in Docker Desktop, it runs a single-node Kubernetes cluster with essential components:

• API Server: Acts as the control plane, handling all requests to the Kubernetes cluster.

• Controller Manager: Ensures that the cluster state matches the desired state.

• Scheduler: Assigns workloads (Pods) to the available node.

• etcd: Stores all cluster data in a distributed key-value store.

• kubelet: Runs on the local node, ensuring containers are running as expected.

• kube-proxy: Manages networking for services within the cluster.

  
  

3. Networking and Service Discovery

Kubernetes creates an internal network for communication between Pods. Here's how it works in Docker Desktop:

• Each Pod gets a unique IP address within the cluster.

• Services expose Pods to enable communication.

• kube-proxy routes network traffic to the appropriate Pod.

In Docker Desktop, Kubernetes networking is simplified, but the fundamental concepts remain the same as in production environments.

4. Storage Management

Kubernetes in Docker Desktop supports Persistent Volumes (PVs) and Persistent Volume Claims (PVCs) to manage storage. You can mount local directories as persistent storage, which is useful for development.

5. Ingress and Load Balancing

Docker Desktop provides a built-in Ingress controller that helps route external traffic to services inside the cluster. Load balancing is done internally using ClusterIP or externally using NodePort and LoadBalancer services.

6. Using kubectl to Interact with Kubernetes

Docker Desktop installs the Kubernetes command-line tool, kubectl, which allows you to interact with the cluster. Some useful commands include:

• kubectl get nodes – Check available nodes.

• kubectl get pods – List all running pods.

• kubectl get services – View exposed services.

  
  

Advantages of Running Kubernetes on Docker Desktop

1. Simplified Setup: No need to install Kubernetes manually; Docker Desktop manages it for you.

2. Local Development: Test Kubernetes configurations before deploying to the cloud.

3. Single-Node Cluster: Ideal for testing and debugging applications.

4. Easy Reset: You can quickly reset the Kubernetes cluster in case of issues.

   
   

Limitations

While Kubernetes in Docker Desktop is great for development, it has some limitations:

• Single-Node Cluster: Not suitable for production workloads.

• Limited Resources: Performance depends on your machine's capabilities.

• Networking Differences: The networking setup may differ from cloud environments.

  
  

Conclusion

Kubernetes in Docker Desktop provides an excellent environment for learning and development. It simplifies container orchestration, allowing developers to test applications locally before deploying them to production clusters. Understanding how it works under the hood helps you optimize workflows, troubleshoot issues, and get the most out of your Kubernetes experience.

If you want to deepen your understanding of Kubernetes and its orchestration capabilities, Kubernetes training online offers a flexible and comprehensive way to advance your skills.