Notes about Kubernetes

This site uses Just the Docs, a documentation theme for Jekyll.

Search

To make an app publicly available to the internet, you must update your configuration file before you deploy the app into a cluster. Different ways exist to make your app accessible from the internet:

  • NodePort: Expose a public port on every worker node and use the public IP address of any worker node to publicly access your service in the cluster.
  • LoadBalancer: Create an external TCP/ UDP load balancer for your app.
  • Ingress: Expose multiple apps in your cluster by creating one external HTTP or HTTPS load balancer that uses a secured and unique public entry point to route incoming requests to your apps.

You can use the NodePort Service to expose a public port on a worker node and use the public IP address to access your Service in the cluster. NodePort can be used for development, but is not recommended for production.

You can use the NodePort service for testing the public access for your app, or when public access is needed for a short amount of time. The public IP address of the worker Node is not permanent. When a worker Node is removed or re-created, a new public IP address is assigned to the worker Node. When you require a stable public IP address and more availability for your Service endpoint, you must use the LoadBalancer Service or Ingress.

Using NodePort

To use the NodePort Service, define a Service section in the configuration file. In the spec section for the service, add the NodePort type.

spec:
  type: NodePort

Optionally, in the ports section, add a NodePort in the 30000 - 32767 range.

ports:
  - port: 80
    nodePort: 31514

Do not specify a NodePort that is already in use by another Service. If you are unsure which NodePorts are already in use, do not assign one. If no NodePort is assigned, a random one is assigned for you. When the app is deployed, you can use the public IP address of any worker Node and the NodePort to form the public URL to access the app in a browser.

If a random NodePort was assigned, you can find out what it is by using the following command, and specify the Service name with the command:

kubectl describe service

For information on how to configure the LoadBalancer service and Ingress controller, see the Kubernetes Documentation.