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Martin Pham
Martin Pham

Posted on • Edited on

Having fun with Kubernetes - Chapter 4

#kubernetes #docker #php #linux

From previous chapter, we were talking about the infrastructure which we're gonna build. In this chapter, let’s install & setup a k8s cluster, with 2 nodes!

We will start with the Master server first

For this Lab, I’m gonna use Virtual machines to simulate servers. I’m using macOS Catalina 10.15.2, VMWare Fusion Pro 11.5.1, with 3 Ubuntu 18.04 VMs (2 CPUs, 1GB RAM, bridged network):

  • kube: master (IP: 192.168.1.33)
  • kube1: node 1 (IP: 192.168.1.34)
  • kube2: node 2 (IP: 192.168.1.35)

Before everything, note that:

  • Kubernetes won’t run if swap enabled
  • Kubernetes master-nodes communication will require some ports opened
  • Kubernetes could face some problems with SELINUX

Alright, let’s start with the Master VM.

Master component 

$ sudo su
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Disable swap

$ swapoff -a
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Also don’t forget to disable swap on reboot, by editing /etc/fstab file

(Optional) Set hostname

$ hostnamectl set-hostname kube
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(Optional) Set static IP

Edit file /etc/netplan/50-cloud-init.yaml to set static IP

/etc/netplan/50-cloud-init.yaml
network:
    renderer: networkd
    ethernets:
        ens33:
            dhcp4: no
            addresses: [192.168.1.33/24]
            gateway4: 192.168.1.1
            nameservers:
                addresses: [8.8.8.8,8.8.4.4]
    version: 2
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Update apt

$ apt update
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Install Docker

$ apt install docker.io
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Auto start Docker

$ systemctl enable docker && systemctl start docker
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Install Kubeadm

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

$ apt-add-repository "deb http://apt.kubernetes.io/ kubernetes-xenial main"

$ apt install kubeadm
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Init Kubeadm

$ kubeadm init --pod-network-cidr=10.244.0.0/16
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After Kubeadm inited, it will give you a command with token to run it on Node servers. It looks like this:

kubeadm join 192.168.1.33:6443 --token xxx --discovery-token-ca-cert-hash xxx
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Create k8s config place

$ mkdir -p $HOME/.kube
$ sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
$ sudo chown $(id -u):$(id -g) $HOME/.kube/config
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Create Virtual network

We’re gonna use flannel for Virtual network

$ kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
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(Optional) Create Docker registry

For this Lab, we’re gonna setup a local insecure Docker registry to store our built images.

$ docker run -d -p 5000:5000 --name registry registry:2
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For security reasons, Docker doesn’t want to connect to an insecure registry.

To allow Docker to use insecure registry, you need to:

Edit file /etc/docker/daemon.json

/etc/docker/daemon.json
{
        "insecure-registries" : ["192.168.1.33:5000"]
}
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Or file /etc/default/docker

/etc/default/docker
DOCKER_OPTS="--insecure-registry 192.168.1.33:5000"
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Restart Docker

$ service docker restart
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(Remember 192.168.1.33 is our Master server’s IP)

Install metrics server

$ cd /etc
$ git clone https://github.com/kubernetes-incubator/metrics-server.git
$ cd metrics-server/
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Edit file /etc/metrics-server/deploy/1.8+/metrics-server-deployment.yaml

      - name: metrics-server
        image: k8s.gcr.io/metrics-server-amd64:v0.3.6
        args:
          - --cert-dir=/tmp
          - --secure-port=4443
        command:
          - /metrics-server
          - --metric-resolution=5s
          - --kubelet-insecure-tls
          - --kubelet-preferred-address-types=InternalIP
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Apply it

kubectl apply -f /etc/metrics-server/deploy/1.8+/metrics-server-deployment.yaml
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Great! you have a working Master server now. Now we're gonna setup the Node servers and connect them together, just 5 minutes ahead :)

Node component

Let’s start on Kube1 (192.168.1.34)

$ sudo su
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Disable swap

$ swapoff -a
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To disable swap on reboot, edit /etc/fstab file

(Optional) Set hostname

$ hostnamectl set-hostname kube1
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(Optional) Set static IP
Edit file /etc/netplan/50-cloud-init.yaml to set static IP

/etc/netplan/50-cloud-init.yaml
network:
    renderer: networkd
    ethernets:
        ens33:
            dhcp4: no
            addresses: [192.168.1.34/24]
            gateway4: 192.168.1.1
            nameservers:
                addresses: [8.8.8.8,8.8.4.4]
    version: 2
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Update apt

$ apt update
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Install Docker

$ apt install docker.io
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**Auto start Docker

$ systemctl enable docker && systemctl start docker
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Install Kubeadm

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

$ apt-add-repository "deb http://apt.kubernetes.io/ kubernetes-xenial main"

$ apt install kubeadm
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Join this node to the master
This command was generated when you setup your Master server

$ kubeadm join xxx:6443 --token xxx --discovery-token-ca-cert-hash xxx
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(Optional) Docker registry

As I told, for some security reasons, Docker doesn’t want to connect to an insecure registry.

To allow Docker to use insecure registry, you need to:

Edit file /etc/docker/daemon.json

/etc/docker/daemon.json
{
        "insecure-registries" : ["192.168.1.33:5000"]
}
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Or edit file /etc/default/docker

/etc/default/docker
DOCKER_OPTS="--insecure-registry 192.168.1.33:5000"
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Restart Docker

$ service docker restart
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Repeat the same, for Kube2 (don’t forget the hostname and static IP)

Done! Now you have a working k8s cluster with Master and 2 Nodes, in the final chapter, we will build our infrastructure on this cluter. And trust me, it's not harder than playing with Lego blocks

Alt Text

The final chapter is here

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