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Accessing Minikube

Introduction

In this chapter, we will study the different access methods to any Kubernetes cluster. We will use kubectl to access Minikube via CLI, the Kubernetes dashboard to access it via GUI, and the curl command, with the right credentials to access it via APIs.

Learning Objectives

By the end of this chapter, you should be able to:

  • Review methods to access any Kubernetes cluster.
  • Configure kubectl for Linux, macOS, and Windows.
  • Access the Minikube dashboard.
  • Access Minikube via APIs.

Accessing Minikube

Any healthy running Kubernetes cluster can be accessed via one of the following methods:

  • Command Line Interface (CLI)
  • Graphical User Interface (GUI)
  • APIs.

These methods are applicable to all Kubernetes clusters.

Accessing Minikube: Command Line Interface (CLI)

kubectl is the Command Line Interface (CLI) tool to manage the Kubernetes cluster resources and applications. In later chapters, we will be using kubectl to deploy the applications and manage the Kubernetes resources.

Accessing Minikube: Graphical User Interface (GUI)

The Kubernetes dashboard provides the Graphical User Interface (GUI) to interact with its resources and containerized applications. In one of the later chapters, we will be using it to deploy a containerized application.

Accessing Minikube: APIs

As we know, Kubernetes has the API server, and operators/users connect to it from the external world to interact with the cluster. Using both CLI and GUI, we can connect to the API server on the master node to perform different operations. We can directly connect to the API server using its API endpoints and send commands to it, as long as we can access the master node and have the right credentials.

Below, you can find a part of the HTTP API space of Kubernetes:

API Server Space

HTTP API space of Kubernetes can be divided into three independent groups:

  • Core Group (/api/v1)
    This group includes objects such as Pods, Services, nodes, etc.
  • Named Group
    This group includes objects in /apis/$NAME/$VERSION format. These different API versions imply different levels of stability and support: Alpha level - it may be dropped at any point in time, without notice. For example, /apis/batch/v2alpha1.
    Beta level - it is well-tested, but the semantics of objects may change in incompatible ways in a subsequent beta or stable release. For example, /apis/certificates.k8s.io/v1beta1.
    Stable level - appears in released software for many subsequent versions. For example, /apis/networking.k8s.io/v1.
  • System-wide
    This group consists of system-wide API endpoints, like /healthz, /logs, /metrics, /ui, etc.

We can either connect to an API server directly via calling the respective API endpoints, or via the CLI/GUI.

Next, we will see how we can access the Minikube environment we set up in the previous chapter.

kubectl

kubectl is generally installed before installing Minikube, but we can also install it later. There are different methods that can be used to install kubectl, which are mentioned in the Kubernetes documentation. Next, we will look at the steps to install kubectl on Linux, macOS, and Windows systems.

Installing kubectl on Linux

To install kubectl on Linux, follow the instructions below:

Download the latest stable kubectl binary

$ curl \
-LO https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/linux/amd64/kubectl

Make the kubectl binary executable

$ chmod +x ./kubectl

Move the kubectl binary to the PATH

$ sudo mv ./kubectl /usr/local/bin/kubectl

Installing kubectl on macOS

There are two ways to install kubectl on macOS: manually and using the Homebrew package manager. Next, we will provide instructions for both methods.

To manually install kubectl on macOS, follow the instructions below:

Download the latest stable kubectl binary

$ curl -LO \
https://storage.googleapis.com/kubernetes-release/release/$(curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt)/bin/darwin/amd64/kubectl

Make the kubectl binary executable

$ chmod +x ./kubectl

Move the kubectl binary to the PATH

$ sudo mv ./kubectl /usr/local/bin/kubectl

To install kubectl on macOS using the Homebrew package manager:

Use the following command

$ brew install kubectl

Installing kubectl on Windows

To install kubectl on Windows, follow the steps below:

Get the latest kubectl release from here

Depending on the latest release, download the kubectl binary In the example below, we are downloading the v1.9.3 release:

https://storage.googleapis.com/kubernetes-release/release/v1.9.3/bin/windows/amd64/kubectl.exe

Once downloaded, move the kubectl binary to the PATH.

kubectl Configuration File

To connect to the Kubernetes cluster, kubectl needs the master node endpoint and the credentials to connect to it. While starting Minikube, the startup process creates, by default, a configuration file, config, inside the .kube directory, which resides in the user's home directory. That configuration file has all the connection details. By default, the kubectl binary accesses this file to find the master node's connection endpoint, along with the credentials. To look at the connection details, we can either see the content of the ~/.kube/config(Linux) file, or run the following command:

$ kubectl config view
apiVersion: v1
clusters:
- cluster:
    certificate-authority: /Users/nkhare/.minikube/ca.crt
    server: https://192.168.99.100:8443
  name: minikube
contexts:
- context:
    cluster: minikube
    user: minikube
  name: minikube
current-context: minikube
kind: Config
preferences: {}
users:
- name: minikube
  user:
    client-certificate: /Users/nkhare/.minikube/apiserver.crt
    client-key: /Users/nkhare/.minikube/apiserver.key

Once kubectl is installed, we can get information about the Minikube cluster with the kubectl cluster-info command:

$ kubectl cluster-info
Kubernetes master is running at https://192.168.99.100:8443

To further debug and diagnose cluster problems, use
'kubectl cluster-info dump'.

You can find more details about the kubectl command line options here.

Using the 'minikube dashboard' Command

As mentioned earlier, the Kubernetes dashboard provides the user interface for the Kubernetes cluster. To access the dashboard of Minikube, we can use minikube dashboard, which would open a new tab on our web browser, displaying the Kubernetes dashboard:

$ minikube dashboard

Kubernetes dashboard

Using the 'kubectl proxy' Command

Using the kubectl proxy command, kubectl would authenticate with the API server on the master node and would make the dashboard available on http://127.0.0.1:8001/api/v1/namespaces/kube-system /services/kubernetes-dashboard:/proxy/#!/overview?namespace=default, as the kubernetes-dashboard service runs inside the kube-system namespace.

$ kubectl proxy
Starting to serve on 127.0.0.1:8001

After running the above command, we can access the dashboard at http://127.0.0.1:8001/api/v1/namespaces/kube-system/services /kubernetes-dashboard:/proxy/#!/overview?namespace=default.

Accessing the Kubernetes dashboard

APIs - with 'kubectl proxy'

When kubectl proxy is configured, we can send requests to localhost on the proxy port:

$ curl http://localhost:8001/
{
 "paths": [
   "/api",
   "/api/v1",
   "/apis",
   "/apis/apps",
   ......
   ......
   "/logs",
   "/metrics",
   "/swaggerapi/",
   "/ui/",
   "/version"
 ]
}%

With the above curl request, we requested all the API endpoints from the API server.

APIs - without 'kubectl proxy'

Without kubectl proxy configured, we can get the Bearer Token using kubectl, and then send it with the API request. A Bearer Token is an access token which is generated by the authentication server (the API server on the master node) and given back to the client. Using that token, the client can connect back to the Kubernetes API server without providing further authentication details, and then, access resources.

Get the token

TOKEN=$(kubectl describe secret -n kube-system $(kubectl get secrets -n kube-system | grep default | cut -f1 -d ' ') | grep -E '^token' | cut -f2 -d':' | tr -d '\t' | tr -d " ")

Get the API server endpoint

$ APISERVER=$(kubectl config view | grep https | cut -f 2- -d ":" | tr -d " ")

Make sure the APISERVER is pointing to your Minikube's IP (for example, in our case, it is pointing to Minikube's IP 192.168.99.100:8443)

$ echo $APISERVER
https://192.168.99.100:8443

Access the API Server using the curl command, as shown below

$ curl $APISERVER --header "Authorization: Bearer $TOKEN" \
--insecure
{
 "paths": [
   "/api",
   "/api/v1",
   "/apis",
   "/apis/apps",
   ......
   ......
   "/logs",
   "/metrics",
   "/swaggerapi/",
   "/ui/",
   "/version"
 ]
}%

Learning Objectives (Review)

You should now be able to:

  • Review methods to access any Kubernetes cluster.
  • Configure kubectl for Linux, macOS, and Windows.
  • Access the Minikube dashboard.
  • Access Minikube via APIs.