kubernetes-installation/README.md

Installation Guide for Kubernetes Cluster

1. Download kubectl

curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"

2. Validate kubectl

curl -LO "https://dl.k8s.io/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl.sha256"
echo "$(<kubectl.sha256) kubectl" | sha256sum --check

3. Install kubectl

sudo install -o root -g root -m 0755 kubectl /usr/local/bin/kubectl

If none-root access (for local user)

chmod +x kubectl
mkdir -p ~/.local/bin/kubectl
mv ./kubectl ~/.local/bin/kubectl
# and then add ~/.local/bin/kubectl to $PATH

4. Verify kubectl installed

kubectl version --client

Install Helm 3

curl https://raw.githubusercontent.com/helm/helm/main/scripts/get-helm-3 | bash

Setup network

cat <<EOF | sudo tee /etc/modules-load.d/k8s.conf
br_netfilter
EOF

cat <<EOF | sudo tee /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF

sudo sysctl --system

Install kubernetes tools

1. Install CNI plugins (required for most pod network)

CNI_VERSION="v0.8.2"
ARCH="amd64"
sudo mkdir -p /opt/cni/bin
curl -L "https://github.com/containernetworking/plugins/releases/download/${CNI_VERSION}/cni-plugins-linux-${ARCH}-${CNI_VERSION}.tgz" | sudo tar -C /opt/cni/bin -xz

DOWNLOAD_DIR=/usr/local/bin
sudo mkdir -p $DOWNLOAD_DIR

2. Install crictl (required for kubeadm / Kubelet Container Runtime Interface (CRI))

CRICTL_VERSION="v1.17.0"
ARCH="amd64"
curl -L "https://github.com/kubernetes-sigs/cri-tools/releases/download/${CRICTL_VERSION}/crictl-${CRICTL_VERSION}-linux-${ARCH}.tar.gz" | sudo tar -C $DOWNLOAD_DIR -xz

3. Install kubeadm, kubelet and add a kubelet systemd service

RELEASE="$(curl -sSL https://dl.k8s.io/release/stable.txt)"
ARCH="amd64"
cd $DOWNLOAD_DIR
sudo curl -L --remote-name-all https://storage.googleapis.com/kubernetes-release/release/${RELEASE}/bin/linux/${ARCH}/{kubeadm,kubelet}
sudo chmod +x {kubeadm,kubelet}

RELEASE_VERSION="v0.4.0"
curl -sSL "https://raw.githubusercontent.com/kubernetes/release/${RELEASE_VERSION}/cmd/kubepkg/templates/latest/deb/kubelet/lib/systemd/system/kubelet.service" | sed "s:/usr/bin:${DOWNLOAD_DIR}:g" | sudo tee /etc/systemd/system/kubelet.service
sudo mkdir -p /etc/systemd/system/kubelet.service.d
curl -sSL "https://raw.githubusercontent.com/kubernetes/release/${RELEASE_VERSION}/cmd/kubepkg/templates/latest/deb/kubeadm/10-kubeadm.conf" | sed "s:/usr/bin:${DOWNLOAD_DIR}:g" | sudo tee /etc/systemd/system/kubelet.service.d/10-kubeadm.conf

sudo systemctl enable --now kubelet

4. Verify installation for kubernetes tools

kubeadm version

5. Configure containerd

cat <<EOF | sudo tee /etc/modules-load.d/containerd.conf
overlay
br_netfilter
EOF

sudo modprobe overlay
sudo modprobe br_netfilter

# Setup required sysctl params, these persist across reboots. (If using crio)
cat <<EOF | sudo tee /etc/sysctl.d/99-kubernetes-cri.conf
net.bridge.bridge-nf-call-iptables  = 1
net.ipv4.ip_forward                 = 1
net.bridge.bridge-nf-call-ip6tables = 1
EOF

# Apply sysctl params without reboot
sudo sysctl --system

sudo mkdir -p /etc/containerd
containerd config default | sudo tee /etc/containerd/config.toml

sudo systemctl restart containerd

If using crio

• Update config

sudo nano /etc/containerd/config.toml

• Change SystemdCgroup from false to true

[plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc]
  [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options]
    SystemdCgroup = true

• Restart containerd service

sudo systemctl restart containerd

6. Disable swap and install docker.io

sudo swapoff -a
wget https://sh.osa.cubetiqs.com/docker-setup.sh
bash docker-setup.sh
sudo systemctl start docker
sudo systemctl enable docker

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 systemctl daemon-reload
sudo systemctl restart docker

Install some required tools

sudo apt-get -y install socat conntrack

7. Cluster on Master node

sudo kubeadm init --pod-network-cidr 172.16.1.0/24

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

Cluster Netowrk with Flannel

kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/k8s-manifests/kube-flannel-rbac.yml

Cluster Network with Calico

kubectl apply -f https://docs.projectcalico.org/manifests/calico.yaml

Kubernetes Dashboard

kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v2.3.1/aio/deploy/recommended.yaml

Deploy Storage Class with External NFS server

helm repo add nfs-subdir-external-provisioner https://kubernetes-sigs.github.io/nfs-subdir-external-provisioner

helm install nfs-subdir-external-provisioner nfs-subdir-external-provisioner/nfs-subdir-external-provisioner \
    --set nfs.server=nfs-server-ip \
    --set nfs.path=/exported-path

Create Service Account for Kubernetes Dashboard Token

• Create file: dashboard-adminuser.yml

apiVersion: v1
kind: ServiceAccount
metadata:
  name: admin-user
  namespace: kube-system

 kubectl apply -f dashboard-adminuser.yml

• Create file: admin-role-binding.yml

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: admin-user
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- kind: ServiceAccount
  name: admin-user
  namespace: kube-system

 kubectl apply -f admin-role-binding.yml

• Get Token

kubectl -n kube-system describe secret $(kubectl -n kube-system get secret | grep admin-user | awk '{print $1}')

Get Kubernetes PKI Hash for Kubeadm

openssl x509 -pubkey -in /etc/kubernetes/pki/ca.crt | openssl rsa -pubin -outform der 2>/dev/null | \
   openssl dgst -sha256 -hex | sed 's/^.* //'

Fix Helm Kube Config

WARNING: Kubernetes configuration file is group-readable. This is insecure. Location: ~/.kube/config
WARNING: Kubernetes configuration file is world-readable. This is insecure. Location: ~/.kube/config

chmod o-r ~/.kube/config
chmod g-r ~/.kube/config

References

• https://kubernetes.io/docs/setup/production-environment/container-runtimes/#docker