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Kubernetes for Developers

You're reading from   Kubernetes for Developers Use Kubernetes to develop, test, and deploy your applications with the help of containers

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Product type Paperback
Published in Apr 2018
Publisher Packt
ISBN-13 9781788834759
Length 374 pages
Edition 1st Edition
Languages
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Author (1):
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Joseph Heck Joseph Heck
Author Profile Icon Joseph Heck
Joseph Heck
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Table of Contents (12) Chapters Close

Preface 1. Setting Up Kubernetes for Development FREE CHAPTER 2. Packaging Your Code to Run in Kubernetes 3. Interacting with Your Code in Kubernetes 4. Declarative Infrastructure 5. Pod and Container Lifecycles 6. Background Processing in Kubernetes 7. Monitoring and Metrics 8. Logging and Tracing 9. Integration Testing 10. Troubleshooting Common Problems and Next Steps 11. Other Books You May Enjoy

Looking at what's built-in and included with Minikube

With Minikube, you can bring up a web-based dashboard for the Kubernetes cluster with a single command:

minikube dashboard

This will open a browser and show you a web interface to the Kubernetes cluster. If you look at the URL address in the browser window, you'll see that it's pointing to the same IP address that was returned from the kubectl cluster-info command earlier, running on port 30000. The dashboard is running inside Kubernetes, and it is not the only thing that is.

Kubernetes is self-hosting, in that supporting pieces for Kubernetes to function such as the dashboard, DNS, and more, are all run within Kubernetes. You can see the state of all these components by asking about the state of all Pods in the cluster:

kubectl get pods --all-namespaces
NAMESPACE     NAME                          READY     STATUS    RESTARTS   AGE
kube-system kube-addon-manager-minikube 1/1 Running 0 6m
kube-system kube-dns-910330662-6pctd 3/3 Running 0 6m
kube-system kubernetes-dashboard-91nmv 1/1 Running 0 6m

Notice that we used the --all-namespaces option in this command. By default, kubectl will only show you Kubernetes resources that are in the default namespace. Since we haven't run anything ourselves, if we invoked kubectl get pods we would just get an empty list. Pods aren't the only Kubernetes resources through; you can ask about quite a number of different resources, some of which I'll describe later in this chapter, and more in further chapters.

For the moment, invoke one more command to get the list of services:

kubectl get services --all-namespaces

This will output all the services:

NAMESPACE     NAME                   CLUSTER-IP   EXTERNAL-IP   PORT(S)         AGE
default kubernetes 10.0.0.1 <none> 443/TCP 3m
kube-system kube-dns 10.0.0.10 <none> 53/UDP,53/TCP 2m
kube-system kubernetes-dashboard 10.0.0.147 <nodes> 80:30000/TCP 2m

Note the service named kubernetes-dashboard has a Cluster-IP value, and the ports 80:30000. That port configuration is indicating that within the Pods that are backing the kubernetes-dashboard service, it will forward any requests from port 30000 to port 80 within the container. You may have noticed that the IP address for the Cluster IP is very different from the IP address reported for the Kubernetes master that we saw previously in the kubectl cluster-info command.

It is important to know that everything within Kubernetes is run on a private, isolated network that is not normally accessible from outside the cluster. We will get into more detail on this in future chapters. For now, just be aware that minikube has some additional, special configuration within it to expose the dashboard.

You have been reading a chapter from
Kubernetes for Developers
Published in: Apr 2018
Publisher: Packt
ISBN-13: 9781788834759
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