Docker Desktop Kubernetes Evolution: Single-Node to Multi-Node

Pre-v4.38.0: Single-Node Clusters

Prior to Docker Desktop v4.38.0, Kubernetes support was limited to a single-node cluster ideal for basic testing:

• Components Included:

  • A standalone Kubernetes API server, kubelet, and etcd (all running in the Docker Desktop VM).
  • Preconfigured Docker CLI integration (kubectl, helm).

• Use Cases:

  • Local development, lightweight testing of deployments, and learning Kubernetes basics.

• Limitations:

  • No multi-node features (e.g., node scaling, pod affinity, or failure simulations).

v4.38.0+: Multi-Node Clusters with kind

Docker Desktop now supports multi-node clusters using kind (Kubernetes IN Docker):

Cluster Provisioning Methods

Docker Desktop offers two options:

Feature	kubeadm (Legacy)	kind (v4.38.0+)
Nodes	Single-node only	Multi-node (control-plane + workers)
Runtime	Docker Engine	containerd (required)
Purpose	Basic local testing	Production-like testing (scaling, networking)
Setup	One-click in Docker Desktop Settings	Requires kind-config.yaml + CLI steps
Load Balancer	Limited to NodePort	Native LoadBalancer support (maps to localhost)
Use Case	Learning Kubernetes basics	Simulating real-world clusters (e.g., node failures)

How It Works

Single-Node (kubeadm)

When you enable Kubernetes via kubeadm:

• Infrastructure Setup:

  • Docker Desktop VM generates TLS certificates, kubeconfig, and downloads core Kubernetes binaries (e.g., kube-apiserver, kube-controller-manager).

• Cluster Boot:

  • A single node acts as both control-plane and worker.
  • Installs CNI (e.g., flannel) for pod networking and storage provisioners (e.g., storageos).

• Isolation:

  • Kubernetes runs in a separate VM namespace; turning it off doesn’t affect Docker containers.

Multi-Node (kind)

With kind, Docker Desktop:

• Node Containers:

  • Spins up Docker containers as Kubernetes nodes (each with containerd runtime).

• Cluster Initialization:

  • Uses kind to bootstrap a cluster from a YAML config (e.g., kind-config.yaml).

• Networking:

  • Sets up a dedicated bridge network for node-to-node communication.

• Load Balancing:

  • Exposes LoadBalancer services on localhost automatically (no MetalLB required).

Why Use Multi-Node Clusters?

• Real-World Testing: Simulate node failures, rolling updates, and pod affinity/anti-affinity.

  • Networking Validation: Test ingress controllers, service meshes (e.g., Istio), and network policies.
  • Cost-Free Scaling: Experiment with horizontal scaling without cloud costs.

Step-by-Step: Create a Multi-Node Cluster

Want to experiment with Kubernetes without cloud costs? Docker Desktop’s built-in Kubernetes (with Kind integration) lets you spin up a local multi-node cluster in minutes. Here’s how to do it:

Getting Started

• Install Docker Desktop 4.38.0
• Select "Enable Kubernetes" and select Kind.

In order to use Kind, you must be signed in to your Docker account. Also, ensure that you have containerd image store enabled. It is enabled by default.

• Select your preferred Kubernetes version

• Select the preferred number of nodes

• Click "Apply and Restart"

• Get K8s Component Status
  

 kubectl get componentstatus
Warning: v1 ComponentStatus is deprecated in v1.19+
NAME                 STATUS    MESSAGE   ERROR
controller-manager   Healthy   ok        
scheduler            Healthy   ok        
etcd-0               Healthy   ok

• Verify the nodes

➜  ~ kubectl get nodes
NAME                    STATUS   ROLES           AGE   VERSION
desktop-control-plane   Ready    control-plane   37m   v1.31.1
desktop-worker          Ready    <none>          37m   v1.31.1
desktop-worker2         Ready    <none>          37m   v1.31.1
desktop-worker3         Ready    <none>          37m   v1.31.1
desktop-worker4         Ready    <none>          37m   v1.31.1
desktop-worker5         Ready    <none>          37m   v1.31.1
desktop-worker6         Ready    <none>          37m   v1.31.1
desktop-worker7         Ready    <none>          37m   v1.31.1
➜  ~ 

Troubleshooting Tips

1. Nodes not showing up?
   Check Docker Desktop logs under Troubleshoot → View logs.

2. Cluster stuck in "Starting"?
   Ensure you’re signed into Docker Hub in Docker Desktop.

3. Resource issues?
   Reduce worker nodes or allocate more RAM/CPU in Docker Settings.

Next Steps: Test Your Single Node Cluster

Deploy a sample app to validate your setup:

➜  ~ kubectl create deployment nginx --image=nginx
deployment.apps/nginx created

➜  ~ kubectl expose deployment nginx --port=80
service/nginx exposed

➜  ~ kubectl get pods,svc
NAME                         READY   STATUS    RESTARTS   AGE
pod/nginx-676b6c5bbc-m8vwp   1/1     Running   0          25s

NAME                 TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1      <none>        443/TCP   39m
service/nginx        ClusterIP   10.96.205.15   <none>        80/TCP    11s
➜  ~ 

Next Steps: Test Your Multi-Node Cluster

git clone https://github.com/collabnix/dockerlabs
cd dockerlabs/kubernetes/workshop/replicaset101

File: nginx_replicaset.yaml

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: web
  labels:
    env: dev
    role: web
spec:
  replicas: 4
  selector:
    matchLabels:
      role: web
  template:
    metadata:
      labels:
        role: web
    spec:
      containers:
      - name: testnginx
        image: nginx

Apply the manifest:

kubectl apply -f nginx_replicaset.yaml

Verify

kubectl get rs
NAME               DESIRED   CURRENT   READY   AGE
nginx-676b6c5bbc   1         1         1       149m
web    

➜  ~ kubectl get pods -o wide
NAME                     READY   STATUS    RESTARTS      AGE    IP           NODE              NOMINATED NODE   READINESS GATES
nginx-676b6c5bbc-m8vwp   1/1     Running   1 (83m ago)   157m   10.244.4.2   desktop-worker5   <none>           <none>
web-7wbfc                1/1     Running   1 (83m ago)   117m   10.244.3.2   desktop-worker3   <none>           <none>
web-grfbn                1/1     Running   1 (83m ago)   117m   10.244.8.2   desktop-worker7   <none>           <none>
web-rnxx6                1/1     Running   1 (83m ago)   117m   10.244.1.2   desktop-worker4   <none>           <none>
web-xbf4d                1/1     Running   1 (83m ago)   117m   10.244.5.2   desktop-worker6   <none>           <none>
➜  ~ 

Found this helpful? Let me know in the comments what you’re building with your local Kubernetes cluster! 🚀