Editing Kubernetes installation

= Installation =
[[Kubernetes]] as of April 2019 can be installed in more that 40 different ways<ref>https://linuxacademy.com/blog/linux-academy/top-ten-ways-not-to-sink-the-kubernetes-ship/?utm_source=intercom&utm_medium=email&utm_campaign=AprilNewsletter2019</ref> and in particular can be installed using your Linux distribution packages or using Kubernetes [[upstream]] version. 
It is also possible to use any of Kubernetes managed solution offered by Cloud Computing provider like [[EKS]] from AWS, [[Google Kubernetes Engine]] (GKE) in [[Google Cloud Platform]] (GCP) or GKE on-prem<ref>https://cloud.google.com/gke-on-prem/</ref> or also some CI/CD tools like [[Jenkins X]] and [[GitLab]]<ref>https://about.gitlab.com/solutions/kubernetes/</ref> that support integration with different Kubernetes Cloud providers.

== Install Kubernetes on Debian/Ubuntu using upstream<ref>
https://www.techrepublic.com/article/how-to-quickly-install-kubernetes-on-ubuntu/
</ref> ==

* Our first step is to download and add the key for the '''Kubernetes and docker''' install. Back at the terminal, issue the following command:

* Add the '''Docker Repository''' on all your servers:
<pre>curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
sudo add-apt-repository    "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
 $(lsb_release -cs) \
 stable"
</pre>

* Add the '''Kubernetes repository''' in your apt source.list on all your servers.
<pre>curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
cat << EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
deb https://apt.kubernetes.io/ kubernetes-xenial main
EOF</pre>

* And now, '''Install Docker, [[kubeadm]], [[kubelet]]<ref>https://kubernetes.io/docs/reference/command-line-tools-reference/kubelet/</ref>, and [[kubectl]]''' on all your servers.
 sudo apt-get update
 sudo apt-get install -y docker-ce=18.06.1~ce~3-0~ubuntu kubelet=1.12.2-00 kubeadm=1.12.2-00 kubectl=1.12.2-00
 sudo [[apt-mark hold]] docker-ce kubelet kubeadm kubectl

==Initialize your [[master node]]==

* Enable '''net.bridge.bridge-nf-call-iptables''' on all your nodes.
<pre>echo "net.bridge.bridge-nf-call-iptables=1" | sudo tee -a /etc/sysctl.conf
sudo sysctl -p</pre>

* On only '''the Kube Master server''', initialize the cluster and configure '''kubectl.'''
<code>sudo [[kubeadm init]] --pod-network-cidr=10.244.0.0/16</code>

When this completes, you'll be presented with the exact command you need to join the nodes to the master.
In case you make any mistake and want to undo your changes you can use: <code>[[kubeadm reset]]</code> <ref>https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm-reset/</ref> command.

* Before you join a node, you need to issue the following commands:

<pre>
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
</pre>

*Install '''the flannel networking''' plugin in the cluster by running this command '''on the Kube Master''' server.
<pre>[[kubectl apply]] -f https://raw.githubusercontent.com/coreos/flannel/bc79dd1505b0c8681ece4de4c0d86c5cd2643275/Documentation/kube-flannel.yml</pre>

* The <code>[[kubeadm init]]</code> command that you ran on the master should output a <code>kubeadm join</code> command containing a '''token and hash'''. You will need to copy that command '''from the master''' and run it on both worker nodes with '''sudo'''.
<pre>sudo kubeadm join $controller_private_ip:6443 --token $token --discovery-token-ca-cert-hash $hash</pre>

* Now you are ready to verify that the cluster is up and running. On the '''Kube Master server''', check the list of nodes.
<pre>kubectl get nodes</pre>

<pre>NAME                      STATUS   ROLES    AGE   VERSION
wboyd1c.mylabserver.com   Ready    master   54m   v1.12.2
wboyd2c.mylabserver.com   Ready    <none>   49m   v1.12.2
wboyd3c.mylabserver.com   Ready    <none>   49m   v1.12.2
</pre>

===Clustering and Nodes===

Kubernetes implements a clustered architecture . In a typical production environment, you will have multiple servers that are able to run your workloads (containers)
These servers which actually run the containers are called '''nodes.'''
A kubernetes cluster has one or more '''control servers''' which manage and control the cluster and host the '''kubernetes API'''. These control server are usually separate from worker nodes, which run applications within the cluster.

*Get a list of nodes: 
::<code>[[kubectl get nodes]]</code>

*Get more information about a specific node:
::<code>[[kubectl describe node]] $node_name</code>

=== [[Networking in Kubernetes ]]===

== Activities ==
* [[CKA v1.18]]: [[Install Kubernetes master and nodes]]

== Related terms ==
* [[Kubernetes (snap install)]]:  <code>[[juju deploy charmed-kubernetes]]</code>
* <code>[[eksctl create cluster]]</code>
* [[Deploy EKS cluster using Terraform]]
* [[Deploy GKE cluster using Terraform]]
* <code>[[kubeadm init]]</code>
* <code>[[kubectl version --short]]</code>

== See also ==
* {{kubectl}}
* {{K8s installation}}


[[Category:Kubernetes]]

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Source: Wikiversity