Setup kubernetes cluster (Ubuntu 18.04.5 LTS)
install docker-ce
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
sudo apt-get update
sudo apt-get install -y docker-ce=18.06.1~ce~3-0~ubuntu
sudo apt-mark hold docker-ce
sudo docker version
install kubeadm, kubelet, kubectl
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=1.15.7-00 kubeadm=1.15.7-00 kubectl=1.15.7-00
sudo apt-mark hold kubelet kubeadm kubectl
kubeadm version
on master node
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
sudo kubeadm init --pod-network-cidr=10.244.0.0/16
kubectl version
on worker nodes: join the cluster with generated code
sudo kubeadm join 172.31.23.220:6443 --token 74vgm6.g7o9e5th7i5h0yih --discovery-token-ca-cert-hash <hash code>
Check if the cluster works
kubectl get nodes
config networking with Flannel
echo "net.bridge.bridge-nf-call-iptables=1" | sudo tee -a /etc/sysctl.conf
sudo sysctl -p
on master node
kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/bc79dd1505b0c8681ece4de4c0d86c5cd2643275/Documentation/kube-flannel.yml
POD
– pod is basic building block of Kubernetes model
– each pod includes multiple containers which make up an application
Note that following commands are executed on master node
create pod
cat << EOF | kubectl create -f -
apiVersion: v1
kind: Pod
metadata:
name: nginx
spec:
containers:
name: nginx
image: nginx
EOF
show pods
kubectl get pods
kubectl get pods -n kube-system
kubectl describe pod nginx
to destroy a pod
kubectl delete pod nginx
A new pod will then be created automatically to replace the destroyed pod.
NETWORKING
Networking model of kubernetes cluster based on a virtual network which help pods to communicate with nodes
We’ll deploy 2 nginx pods
cat << EOF | kubectl create -f -
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx
labels:
app: nginx
spec:
replicas: 2
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.15.4
ports:
- containerPort: 80
EOF
create a busybox pod
cat << EOF | kubectl create -f -
apiVersion: v1
kind: Pod
metadata:
name: busybox
spec:
containers:
name: busybox
image: radial/busyboxplus:curl
args: sleep "1000"
EOF
get IP of pods
kubectl get pods -o wide
get IP of nginx pod then contact that pod from busybox pod
kubectl exec busybox -- curl $nginx_pod_ip
Show Architecture
kubectl get pods -n kube-system
sudo systemctl status kubelet
create deployment
cat <<EOF | kubectl create -f -
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
labels:
app: nginx
spec:
replicas: 2
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.15.4
ports:
- containerPort: 80
EOF
get list of deployments
kubectl get deployments
get more info about a deployment
kubectl describe deployment nginx-deployment
kubectl get pods
SERVICE
Kubernetes cluster uses services instead of IP to identify a nodes because IP changes when pods being recreated.
create NodePort service
cat << EOF | kubectl create -f -
kind: Service
apiVersion: v1
metadata:
name: nginx-service
spec:
selector:
app: nginx
ports:
protocol: TCP
port: 80
targetPort: 80
nodePort: 30080
type: NodePort
EOF
— get list of services in the cluster
kubectl get services
check if service works
curl localhost:30080
Deploy app
kubectl delete service nginx-service
cd ~/
git clone https://github.com/linuxacademy/robot-shop.git
kubectl create namespace robot-shop
kubectl -n robot-shop create -f ~/robot-shop/K8s/descriptors/
kubectl get pods -n robot-shop -w
run app
http://$kube_server_public_ip:30080
Deploy app with Helm
install helm
sudo snap install helm --classic
install helm chart
helm repo add stable https://kubernetes-charts.storage.googleapis.com/
helm search repo stable
helm install stable/mysql --generate-name
helm install my-wordpress-x --set -service.type=clusterip --set persistence.storageClass=rook-ceph-block stable/wordpress --set mariadb.master.persistence.storageClass=rook-ceph-block
Done!
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