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Kubernetes Getting Started

Prerequisites​

Docker Configuration​

Check Docker info:

sudo docker info

Configure Docker daemon:

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

Enable cgroups in /boot/cmdline.txt:

cgroup_enable=cpuset cgroup_enable=memory cgroup_memory=1 swapaccount=1

System Configuration​

# Enable net.bridge.bridge-nf-call-iptables and -iptables6
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

Installation​

sudo apt update && sudo apt install -y kubelet kubeadm kubectl

Cluster Initialization​

Generate token:

TOKEN=$(sudo kubeadm token generate)
echo $TOKEN

Initialize control plane:

sudo kubeadm init --token=${TOKEN} --kubernetes-version=v1.18.2 --pod-network-cidr=10.244.0.0/16

Configure kubectl​

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

Networking (CNI)​

Deploy Flannel:

curl -sSL https://raw.githubusercontent.com/coreos/flannel/v0.12.0/Documentation/kube-flannel.yml | kubectl apply -f -

Adding Worker Nodes​

Run the join command on worker nodes:

sudo kubeadm join <control-plane-host>:6443 --token <token> --discovery-token-ca-cert-hash sha256:<hash>

Verification​

Create Namespace​

kubectl create namespace kube-verify
kubectl get namespaces

Deploy Verification App​

cat << EOF | kubectl create -f -
apiVersion: apps/v1
kind: Deployment
metadata:
  name: kube-verify
  namespace: kube-verify
  labels:
    app: kube-verify
spec:
  replicas: 3
  selector:
    matchLabels:
      app: kube-verify
  template:
    metadata:
      labels:
        app: kube-verify
    spec:
      containers:
      - name: nginx
        image: quay.io/clcollins/kube-verify:01
        ports:
        - containerPort: 8080
EOF

Check deployment:

kubectl get all -n kube-verify

Expose Service​

cat << EOF | kubectl create -f -
apiVersion: v1
kind: Service
metadata:
  name: kube-verify
  namespace: kube-verify
spec:
  selector:
    app: kube-verify
  ports:
  - protocol: TCP
    port: 80
    targetPort: 8080
EOF

Test access:

curl <service-ip>