Docker Kubernetes in DevOps

Kubernetes is the tool used to deploy containers inside a cluster. It is created as helper tools that can be used to manage a cluster of containers and treat all servers as a single unit.Kubernetes is a tool that can help you deploy Docker containers. It's only one of several such tools. You don't have to use it to use Docker  but you can't use Kubernetes without also using software from Docker. Docker is a platform and tool for building, distributing, and running Docker containers. Kubernetes is a container orchestration system for Docker containers.
The following diagram shows in a simplistic format how Kubernetes works from an architecture point of view.

Kubernetes has several components in its architecture :

etcd

Flannel

Kube-apiserver

Kube-controller-manager

Kube-scheduler

Kubelet

Kube-proxy

Docker - Working

Now we will see how to install Kubenetes via kubeadm.

This is a tool which helps in the installation of Kubernetes.

Step 1 - Ensure that the Ubuntu server version you are working on is 16.04.

Step 2 - Ensure that you generate a ssh key which can be used for ssh login.

Using the following command:

ssh-keygen

Step 3 - Next, depending on the version of Ubuntu you have, you will need to add the relevant site to the docker.list for apt package manager.

We can do it using the following commands :

 curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | apt-key add-echo "deb

  http://apt.kubernetes.io/kubernetes-xenial main" | sudo tee/etc/apt/source.list.d/docker.list

Step 4 - We then issue an apt-get update to ensure all packages are downloaded on the Ubuntu server.

Step 5 - Install the Docker package as detailed in the earlier chapters.

Step 6 - Now it's time to install kubernetes by installing the following packages.

Step 7 - Once all kubernetes packages are downloaded, it's time to start the kubernetes controller using the following command - kubeadm init

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