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installation-configuration-validation.md

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Installation, Configuration & Validation (12%)

Design a Kubernetes cluster

Solution

We will use a three node cluster, with one master node and two worker nodes.

Three Libvirt/KVM nodes (or any cloud provider you are using):

  • k8s-master: 2 vCPUs, 4GB RAM, 40GB Disk, 172.16.1.11/24
  • k8s-worker-1: 2 vCPUs, 2GB RAM, 40GB Disk, 172.16.1.21/24
  • k8s-worker-2: 2 vCPUs, 2GB RAM, 40GB Disk, 172.16.1.22/24

OS description:

$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 18.04.4 LTS
Release:	18.04
Codename:	bionic

Install Kubernetes masters and nodes

Solution

If you don't have cluster nodes yet, check the terraform deployment from below: Provision underlying infrastructure to deploy a Kubernetes cluster

Installation from scratch is too time consuming. We will be using KubeADM (v1.17) to install the Kubernetes cluster.

Install container runtime

Solution

Doc: https://kubernetes.io/docs/setup/production-environment/container-runtimes/

Do this on all three nodes:

# Install Docker CE
## Set up the repository:
### Install packages to allow apt to use a repository over HTTPS
sudo apt-get update && sudo apt-get install -y \
  apt-transport-https ca-certificates curl software-properties-common gnupg2

### Add Docker’s official GPG key
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

### Add Docker apt repository.
sudo add-apt-repository \
  "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) \
  stable"

## Install Docker CE.
sudo apt-get update && sudo apt-get install -y \
  containerd.io=1.2.10-3 \
  docker-ce=5:19.03.4~3-0~ubuntu-$(lsb_release -cs) \
  docker-ce-cli=5:19.03.4~3-0~ubuntu-$(lsb_release -cs)

# Setup daemon.
cat << EOF | sudo tee /etc/docker/daemon.json
{
  "exec-opts": ["native.cgroupdriver=systemd"],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "100m"
  },
  "storage-driver": "overlay2"
}
EOF

sudo mkdir -p /etc/systemd/system/docker.service.d

# Restart docker.
sudo systemctl daemon-reload
sudo systemctl restart docker

Install kubeadm, kubelet and kubectl

Solution

Doc: https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/

Do this on all three nodes:

sudo apt-get update && sudo apt-get install -y apt-transport-https curl
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
sudo apt-get update
sudo apt-get install -y kubelet=1.17.4-00 kubeadm=1.17.4-00 kubectl=1.17.4-00
sudo apt-mark hold kubelet kubeadm kubectl

Create a cluster with KubeADM

Solution

Doc: https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/

On master node:

sudo kubeadm init --pod-network-cidr=10.244.0.0/16

Run the output of the init command on worker nodes:

sudo kubeadm join 172.16.1.11:6443 --token h8vno9.7eroqaei7v1isdpn \
    --discovery-token-ca-cert-hash sha256:44f1def2a041f116bc024f7e57cdc0cdcc8d8f36f0b942bdd27c7f864f645407

On master node again:

# Configure kubectl access
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config

# Deploy Flannel as a network plugin
kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/2140ac876ef134e0ed5af15c65e414cf26827915/Documentation/kube-flannel.yml

Check that your nodes are running and ready

Solution 

kubectl get nodes
NAME           STATUS   ROLES    AGE     VERSION
k8s-master     Ready    master   11m     v1.17.4
k8s-worker-1   Ready    <none>   3m12s   v1.17.4
k8s-worker-2   Ready    <none>   3m10s   v1.17.4

Configure secure cluster communications

Solution

Doc: https://kubernetes.io/docs/tasks/administer-cluster/securing-a-cluster/

KubeADM already manages TLS certificate creation for the cluster. Check how to do it the hard way through cfssl: https://github.com/kelseyhightower/kubernetes-the-hard-way/blob/master/docs/04-certificate-authority.md

Configure a Highly-Available Kubernetes cluster

Solution

Doc: https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/high-availability/

Know where to get the Kubernetes release binaries

Solution

Doc: https://kubernetes.io/docs/setup/release/notes/

wget https://dl.k8s.io/v1.18.0/kubernetes.tar.gz
tar xzvf kubernetes.tar.gz
cd kubernetes/
cluster/get-kube-binaries.sh
tar xzvf server/kubernetes-server-linux-amd64.tar.gz
ls kubernetes/server/bin/
# You will find: kube-apiserver, kube-controller-manager, kube-scheduler, kube-proxy, kubelet, kubeadm, kubectl, ...

Provision underlying infrastructure to deploy a Kubernetes cluster

Solution

You can use any cloud provider (AWS, Azure, GCP, OpenStack, etc.) and multiple tools to provision nodes for your Kubernetes cluster.

Here is an example where we use a local libvirt/KVM baremetal node with terraform (v0.12.20) to provision a three node cluster as described in Design a Kubernetes cluster above.

mkdir terraform
cd terraform
wget https://raw.githubusercontent.com/alijahnas/CKA-practice-exercises/master/terraform/cluster-infra.tf
terraform plan
terraform apply

Choose a network solution

Solution

Docs:

Install and use kubeadm to install, configure, and manage Kubernetes clusters

Solution

Check section "Install Kubernetes masters and nodes" above.