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Waji
Waji

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Docker & Kubernetes Setup

#linux #docker #kubernetes

Introduction

Docker is a platform that allows developers to create, deploy, and run applications in containers. Docker Compose simplifies managing multi-container applications by defining and running multiple containers as a single application with dependencies and configurations. Compose plugins extend the functionality of Docker Compose, allowing developers to add new commands, modify behavior, or integrate with external services

Docker Virtualization

Kubernetes is an open-source platform for container orchestration and management that automates deployment, scaling, and management of containerized applications. It is often used in conjunction with Docker to manage containerized applications.

✨ Kubernetes provides a framework for automating deployment, scaling, and operations of application containers across clusters of hosts, while Docker provides a standardized way to package and distribute those containers

👉 I will be installing Docker in 3 CentOS7 Virtual Machines in my VMWare workstation

192.168.1.10 👉 Master
192.168.1.20 👉 Node-1
192.168.1.30 👉 Node-2

Before I begin, I will share official documentations available on installing the docker engine and compose

Installing Docker

In all systems,

yum -y install yum-utils

# Saving the docker repository to install docker from it
yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
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Checking docker files

yum list docker-ce --showduplicates | sort -r
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👉 This should show us different versions of docker available. I will be proceeding with version 18.x

Installing the Docker Engine

yum -y install docker-ce-18.09.8 docker-ce-cli-18.09.8 containerd.io docker-compose-plugin
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Checking the docker version

rpm -qa | grep docker
docker-ce-cli-18.09.8-3.el7.x86_64
docker-compose-plugin-2.6.0-3.el7.x86_64
docker-ce-18.09.8-3.el7.x86_64
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Enabling and starting the docker service

systemctl start docker
systemctl enable docker
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We can check the Docker version

docker version
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👉 Working only from the 'Master' Linux

Installing Docker Compose

curl -SL https://github.com/docker/compose/releases/download/v2.2.3/docker-compose-linux-x86_64 -o /usr/local/bin/docker-compose
ln -s /usr/local/bin/docker-compose /usr/bin/docker-compose
chmod +x /usr/local/bin/docker-compose
docker-compose version
Docker Compose version v2.2.3
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Installing Kubernetes

👉 I have VSCode and Kubernetes installed in my Host PC to write manifest files for Kubernetes with ease

✨ From the 'Master' VM

Configuring SWAP memory to be deactivated

sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab
swapoff -a
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Creating the daemon.json file

vi /etc/docker/daemon.json

{
    "exec-opts": ["native.cgroupdriver=systemd"]
}
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Reloading the daemon and restarting docker

systemctl daemon-reload
systemctl restart docker
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👉 This will change the Docker cgroup drive

Adding the Kubernetes Local Repository

vi /etc/yum.repos.d/kubernetes.repo

[kubernetes]
name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=0
repo_gpgcheck=0
gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg
       https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg

# Installing Kuber
yum install -y kubelet-1.19.16-0.x86_64 kubectl-1.19.16-0.x86_64 kubeadm-1.19.16-0.x86_64
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Confirming kubernetes installation

rpm -qa | grep kube
kubelet-1.19.16-0.x86_64
kubectl-1.19.16-0.x86_64
kubernetes-cni-0.8.7-0.x86_64
kubeadm-1.19.16-0.x86_64
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Enabling ports used

firewall-cmd --permanent --add-port=80/tcp
firewall-cmd --permanent --add-port=443/tcp
firewall-cmd --permanent --add-port=2376/tcp
firewall-cmd --permanent --add-port=2379/tcp
firewall-cmd --permanent --add-port=2380/tcp
firewall-cmd --permanent --add-port=6443/tcp
firewall-cmd --permanent --add-port=8472/udp
firewall-cmd --permanent --add-port=9099/tcp
firewall-cmd --permanent --add-port=10250/tcp
firewall-cmd --permanent --add-port=10251/tcp
firewall-cmd --permanent --add-port=10252/tcp
firewall-cmd --permanent --add-port=10254/tcp
firewall-cmd --permanent --add-port=10255/tcp
firewall-cmd --permanent --add-port=30000-32767/tcp
firewall-cmd --permanent --add-port=30000-32767/udp
firewall-cmd --permanent --add-masquerade
firewall-cmd --reload
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Configuring the Kuber cluster on our Master

kubeadm init --apiserver-advertise-address=192.168.1.10 --pod-network-cidr=10.244.0.0/16

Then you can join any number of worker nodes by running the following on each as root:

kubeadm join 192.168.1.10:6443 --token y20gfe.s5kx71a4nh0gzhsw \
    --discovery-token-ca-cert-hash sha256:7c46fa0f4ce64ea4642183250afb3305ca17a89867ed877e2eacdf2a835095b3
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👉 The final line says to use the "join" command when adding nodes to the cluster.

👉 I specified the Master Node's IP address with the "apiserver-advertise-address" command and the network area for Pod usage with the "pod-network-cidr" command

Moving the authentication data to use kubectl under root user's Home directory .kube

mkdir -p $HOME/.kube
cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
chown $(id -u):$(id -g) $HOME/.kube/config
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Installing the Network Plugin to be used in Kuber cluster (Flannel)

curl -O -L https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
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👉 As I am using a VM with NAT connection, I needed to add the NIC device name to the flannel.yml file

vi kube-flannel.yml

args:
        - --ip-masq
        - --kube-subnet-mgr
        - --iface=ens32
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Now, we just need to apply the flannel plugin

kubectl apply -f kube-flannel.yml
systemctl restart kubelet
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✨ From Both Node-1 and Node-2 VMs

👉 Same steps as Master node till firewall settings in both nodes

After firewall settings are done, we will use the join command that we got from the Master node

kubeadm join 192.168.1.10:6443 --token 172vji.r0u77jcmcnccm6no \
    --discovery-token-ca-cert-hash sha256:72b9648c647f724ab52471847cb06c47b23097375f2e67633b745fc69db16e8d
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👉 This will add both nodes to the Kuber cluster created by the Master

This node has joined the cluster:
* Certificate signing request was sent to apiserver and a response was received.
* The Kubelet was informed of the new secure connection details.

Run 'kubectl get nodes' on the control-plane to see this node join the cluster.
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Upon successful joining,

kubectl get nodes
NAME     STATUS   ROLES    AGE    VERSION
master   Ready    master   107m   v1.19.16
node-1   Ready    <none>   91s    v1.19.16
node-2   Ready    <none>   48s    v1.19.16
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We can also check pods

kubectl get pods --all-namespaces
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👉 A pod represents a single instance of a running process in the cluster

✍ Today I walked through installing Docker and Kubernetes in Linux systems and joined 2 working nodes to the Master Kuber cluster

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