kube-3-kind

How to Spin Up 3 Kubernetes Clusters with Docker Desktop

Docker Desktop provides a built-in Kubernetes environment but supports only a single-cluster setup natively. To run multiple Kubernetes clusters, you need to use Kind (Kubernetes IN Docker) or K3d (K3s in Docker).

This tutorial will show you how to spin up three Kubernetes clusters using Kind, which is an easy-to-use tool for running Kubernetes in Docker containers.

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Prerequisites

Before we begin, ensure you have the following installed:

• Docker Desktop (with Kubernetes enabled)
  👉 Install Docker

• kubectl (Kubernetes CLI)
  👉 Install kubectl

• Kind (Kubernetes IN Docker)
  👉 Install it using:

  curl -Lo ./kind https://kind.sigs.k8s.io/dl/latest/kind-linux-amd64
  chmod +x ./kind
  sudo mv ./kind /usr/local/bin/kind

  For macOS users, install via Homebrew:

  brew install kind

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Step 1: Create Kind Cluster Configurations

We will define three clusters: cluster1, cluster2, and cluster3.

Create a configuration file for each cluster:

Cluster 1 - cluster1.yaml

kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
name: cluster1
nodes:
  - role: control-plane
  - role: worker
  - role: worker
networking:
  podSubnet: "10.244.0.0/16"
  serviceSubnet: "10.96.0.0/16"

Cluster 2 - cluster2.yaml

kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
name: cluster2
nodes:
  - role: control-plane
  - role: worker
  - role: worker
networking:
  podSubnet: "10.245.0.0/16"
  serviceSubnet: "10.97.0.0/16"

Cluster 3 - cluster3.yaml

kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
name: cluster3
nodes:
  - role: control-plane
  - role: worker
  - role: worker
networking:
  podSubnet: "10.246.0.0/16"
  serviceSubnet: "10.98.0.0/16"

---

Step 2: Create the Clusters

Run the following commands in your terminal:

kind create cluster --config cluster1.yaml
kind create cluster --config cluster2.yaml
kind create cluster --config cluster3.yaml

This will create three separate Kubernetes clusters inside Docker containers.

You can verify the running clusters using:

kind get clusters

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Step 3: Configure kubectl to Switch Between Clusters

Since we have multiple clusters, we need to switch contexts when managing them.

1. Get the current kubeconfig settings:

   kubectl config get-contexts

2. Switch to cluster1:

   kubectl config use-context kind-cluster1

3. Check nodes in cluster1:

   kubectl get nodes

4. Switch to cluster2:

   kubectl config use-context kind-cluster2

5. Check nodes in cluster2:

   kubectl get nodes

6. Similarly, switch to cluster3:

   kubectl config use-context kind-cluster3

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Step 4: Deploy a Sample App in Each Cluster

Now, let’s deploy a simple Nginx web server on each cluster.

1. Create a deployment manifest nginx-deployment.yaml:

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: nginx
   spec:
     replicas: 2
     selector:
       matchLabels:
         app: nginx
     template:
       metadata:
         labels:
           app: nginx
       spec:
         containers:
           - name: nginx
             image: nginx:latest
             ports:
               - containerPort: 80

2. Apply this deployment on each cluster:

   kubectl --context kind-cluster1 apply -f nginx-deployment.yaml
   kubectl --context kind-cluster2 apply -f nginx-deployment.yaml
   kubectl --context kind-cluster3 apply -f nginx-deployment.yaml

3. Check the running pods:

   kubectl --context kind-cluster1 get pods
   kubectl --context kind-cluster2 get pods
   kubectl --context kind-cluster3 get pods

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Step 5: Expose the Application

We need to expose the Nginx deployment using a Service.

1. Create a service.yaml file:

   apiVersion: v1
   kind: Service
   metadata:
     name: nginx-service
   spec:
     selector:
       app: nginx
     ports:
       - protocol: TCP
         port: 80
         targetPort: 80
     type: LoadBalancer

2. Apply the service on all three clusters:

   kubectl --context kind-cluster1 apply -f service.yaml
   kubectl --context kind-cluster2 apply -f service.yaml
   kubectl --context kind-cluster3 apply -f service.yaml

3. Get the service details:

   kubectl --context kind-cluster1 get svc
   kubectl --context kind-cluster2 get svc
   kubectl --context kind-cluster3 get svc

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Step 6: Pull the docker image from psyunix docker hub and run it

kubectl --context kind-cluster1 run cmatrix --image=psyunix/vm:cmatrix -it

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Step 7: Clean Up

When you are done, delete the clusters to free up resources.

kind delete cluster --name cluster1
kind delete cluster --name cluster2
kind delete cluster --name cluster3

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Conclusion

You have successfully created three separate Kubernetes clusters using Kind on Docker Desktop. You deployed Nginx and exposed it via a service in each cluster. This setup is useful for testing multi-cluster deployments, service meshes (like Istio or Linkerd), and Kubernetes federation.