How-To: Access Applications on Crusoe Managed Kubernetes (CMK) Using NodePort

This article explains how to use NodePort to expose Kubernetes applications on CMK, how it works, how to enable external access, and what to consider when troubleshooting.

Environment

• Crusoe Managed Kubernetes (CMK)

• Kubernetes version: v1.30.8-cmk.28

• Node pool: c1a.2x instance type

• Subnet: default-subnet-eu-iceland1-a

• Terraform used to provision cluster (example below)

• Application example: Jupyter Notebook (jupyter/base-notebook)

Procedure

A NodePort is a Kubernetes service type that exposes a specific port (between 30000–32767) on each worker node in the cluster. This allows external clients to reach applications by hitting <NodeIP>:<NodePort> directly.

In this example, we use Jupyter Notebook as the workload to demonstrate the NodePort setup.

1. Deploy Your Application (Jupyter as an Example)

   Create a Kubernetes namespace

   kubectl create namespace jupyter-lab

   Define a Deployment manifest:

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: jupyter-notebook
     namespace: jupyter-lab
   spec:
     replicas: 2
     selector:
       matchLabels:
         app: jupyter
     template:
       metadata:
         labels:
           app: jupyter
       spec:
         containers:
         - name: notebook
           image: jupyter/base-notebook:latest
           ports:
           - containerPort: 8888 #The container running inside the pod will be listening on port 8888.
           args:
           - start-notebook.sh
           env:
           - name: JUPYTER_ENABLE_LAB
             value: "yes"

   Container Port (8888) will  be used by the Service’s targetPort, which maps external traffic to the pod’s actual listening port, Apply the deployment file. 

   kubectl apply -f jupyter-deployment.yaml

   Confirm pods are running:

   kubectl get pods -n jupyter-lab

2. Create a NodePort Service

   Expose the deployment using a NodePort service. Ensure the selector in the Service exactly matches the labels defined on your Pods. If these do not match, the Service will not forward traffic to your application.

   apiVersion: v1
   kind: Service
   metadata:
     name: jupyter-nodeport-service
     namespace: jupyter-lab
   spec:
   type: NodePort
     selector:
     app: jupyter
     ports:
       - port: 8888 #The port the service listens on inside the cluster
         targetPort: 8888 #The port the container exposes
         nodePort: 30036 #The port exposed on the node externally

   Apply the service:

   kubectl apply -f jupyter-nodeport-service.yaml

   Check the service:

   kubectl get svc -n jupyter-lab

   Output should look like:

   NAME   TYPE   CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
   jupyter-nodeport-service   NodePort   10.233.25.136   <none>   8888:30036/TCP   1m

3. You can verify the Service is correctly linked to the Pods by running below command. Look under Endpoints:  it should list IPs and ports. If it says <none>, the label match is broken.

   kubectl describe svc jupyter-nodeport-service -n jupyter-lab

4. By default, NodePort traffic is blocked at the Crusoe Cloud firewall level.

   You must create a firewall rule to allow TCP traffic on the NodePort.

   Example Firewall Rule:

   Name	Protocol	Source	Port	Subnet
   jupyter-nb-ingress	TCP	0.0.0.0/0	30036	default-subnet-eu-iceland1-a

   Note: You must associate this rule with the correct VPC/subnet used by your Kubernetes nodes.

5. Access the Application

   Get your node external IP using below command

   kubectl get nodes -o wide

   Output

   NAME STATUS ... INTERNAL-IP EXTERNAL-IP ...
   np-abc123... Ready 172.27.52.145 216.86.17.xx ...

   You can now access the service at: http://216.86.17.xx:30036 

Note

• Make sure the pod is running and reachable on the targetPort internally. 
• Use curl http://localhost:30036 from the node to verify internal reachability.
• Check Crusoe firewall if external access isn’t working — firewall rules must match the node port.

Related Articles

• Crusoe Managed Kubernetes Documentation
• Kubernetes NodePort Service Reference