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00-setup-kubectl-linux.md

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Setup kubectl

NB: if you are in an instructor facilited training, please don't run the commands below, as your machine will have already been configured with the proper access.

It is assumed that you are provided with a kubernetes cluster by the instructor. Before you are able to do anything on the cluster, you need to be able to talk to this cluster from/using your computer. kubectl - short for Kubernetes Controller - is the command line tool to talk to a Kubernetes cluster. To get that on your computer follow the instructions for kubectl on this page: https://kubernetes.io/docs/tasks/tools/install-kubectl-linux/

Kubectl is a go binary which allows you to execute commands on your cluster. Your cluster could be a single node VM, such as minikube, or a set of VMs on your local computer or somewhere on a host in your data center, a bare-metal cluster, or a cluster provided by any of the cloud providers - as a service - such as GCP.

Note: Due to restrictions with virtualization inside a virtual machine (nested virtualization), you cannot run minikube on cloud VMs. Minikube is a part of the Kubernetes open source project, with the single goal of getting a simple cluster up and running with just one virtual machine acting as node.

For the remainder of this workshop, we assume you have a Kubernetes cluster on google cloud. For instructions on connecting to various types of Kubernetes cluster, check this article

Authenticate to your Google k8s cluster:

To authenticate against your cluster, you will need a gmail account. Then, run:

 # cluster connection via service account

 # Install the tools
export CLOUD_SDK_REPO="cloud-sdk-$(lsb_release -c -s)"
echo "deb http://packages.cloud.google.com/apt $CLOUD_SDK_REPO main" | sudo tee -a /etc/apt/sources.list.d/google-cloud-sdk.list
curl https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
sudo apt-get update && sudo apt-get install google-cloud-sdk

 # Create key file on your vm - the instructor will mail you the contents
vi keyfile.json

 # authenticate with cloud
gcloud auth activate-service-account --key-file keyfile.json

 # Get the cluster credentials for kubectl
gcloud container clusters get-credentials training-cluster --zone europe-west1-b --project praqma-education

Google will do some magic under the hood, which does a few things:

  • Fetches certificates and tokens (secrets)
  • Puts them into the Kubernetes configuration file, located at /home/.kube/config

Verify configuration:

You can verify this by looking at the config file:

kubectl config view

You should see something like this:

apiVersion: v1
clusters:
- cluster:
    certificate-authority-data: REDACTED
    server: https://1.2.3.4
  name: gke_praqma-education_europe-west1-b_dcn-cluster-35
contexts:
- context:
    cluster: gke_praqma-education_europe-west1-b_dcn-cluster-35
    user: gke_praqma-education_europe-west1-b_dcn-cluster-35
  name: gke_praqma-education_europe-west1-b_dcn-cluster-35
current-context: gke_praqma-education_europe-west1-b_dcn-cluster-35
kind: Config
preferences: {}
users:
- name: gke_praqma-education_europe-west1-b_dcn-cluster-35
  user:
    password: secret-password-ea4a2fb76dc9
    username: admin

Furthermore you should now have access to the google cloud cluster! Verify by looking at the nodes for the cluster:

kubectl get nodes

You should be able to see something similar to what is shown below:

$ kubectl get nodes
NAME                                             STATUS    ROLES     AGE       VERSION
ip-172-20-40-108.eu-central-1.compute.internal   Ready     master    1d      v1.8.0
ip-172-20-49-54.eu-central-1.compute.internal    Ready     node      1d      v1.8.0
ip-172-20-60-255.eu-central-1.compute.internal   Ready     node      1d      v1.8.0

If you add the -o wide parameters to the above command, you will also see the public IP addresses of the nodes:

$ kubectl get nodes -o wide
NAME                                            STATUS    ROLES     AGE       VERSION        EXTERNAL-IP     OS-IMAGE                             KERNEL-VERSION   CONTAINER-RUNTIME
gke-dcn-cluster-35-default-pool-dacbcf6d-3918   Ready     <none>    17h       v1.8.8-gke.0   35.205.22.139   Container-Optimized OS from Google   4.4.111+         docker://17.3.2
gke-dcn-cluster-35-default-pool-dacbcf6d-c87z   Ready     <none>    17h       v1.8.8-gke.0   35.187.90.36    Container-Optimized OS from Google   4.4.111+         docker://17.3.2

Note: On Kubernetes clusters provided by a Kubernetes service provider, you will only see worker nodes as a result of executing the above command. On other clusters, you will see both master and worker nodes.

$ kubectl get nodes -o wide
NAME                                             STATUS    ROLES     AGE     VERSION   EXTERNAL-IP     OS-IMAGE                      KERNEL-VERSION   CONTAINER-RUNTIME
ip-172-20-40-108.eu-central-1.compute.internal   Ready     master    1d      v1.8.0    1.2.3.4         Debian GNU/Linux 8 (jessie)   4.4.78-k8s       docker://1.12.6
ip-172-20-49-54.eu-central-1.compute.internal    Ready     node      1d      v1.8.0    2.3.4.5         Debian GNU/Linux 8 (jessie)   4.4.78-k8s       docker://1.12.6
ip-172-20-60-255.eu-central-1.compute.internal   Ready     node      1d      v1.8.0    5.6.7.8         Debian GNU/Linux 8 (jessie)   4.4.78-k8s       docker://1.12.6

Note: Depending on the setup for this workshop, you may not be the only tenant on the cluster; you may be sharing it with the rest of the people around you in the course! So be careful!