Ansible role to setup 1 master +2 node kubernetes cluster (more nodes can be added)

setup centos VMs
configure hostnames
Update hosts file template in ../roles/kubernetes-deploy/files/hosts.template with host names and ipaddress
setup password less auth between your Ansible host and Kubernetes nodes

$ ssh-copyid root@kube-nodes?

setup Ansible inventory

kube-master.rmohan.com hostrole=master
kube-node1.rmohan.com hostrole=node
kube-node2.rmohan.com hostrole=node

Run Ansible Role

$ ansible-playbook install-kubernetes-centos7.yml

Role does follwoing

• updated os
• reboot
• setup kubernetes environment

upon completion of ansible play, copy following command from stdout of play and run on all node as root

kubeadm join 192.168.1.240:6443 –token ce2b82.hbu4u9x12luwbhyr –discovery-token-ca-cert-hash sha256:510573c7ec722ac20674e96403517e97696e2110635d57455d869bae06ffefaa

• Validation on Master

kubectl get nodes (check node status)

kubectl get pods –all-namespaces (you may need to wait for sometime to get the containers up)

[RUN ALL BELOW COMMADS on ALL NODES]

yum update
yum install -y epel-release

yum install docker [v1.11 or 1.12 or 1.13]

setup kubernates respos

kubeadm kubectl kubelet

[root@kubmaster yum.repos.d]

# cat kubernetes.repo

[kubernetes]

name=Kubernetes
baseurl=https://packages.cloud.google.com/yum/repos/kubernetes-el7-x86_64
enabled=1
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://packages.cloud.google.com/yum/doc/yum-key.gpg https://packages.cloud.google.com/yum/doc/rpm-package-key.gpg

setenforce 0

yum install -y kubelet kubeadm kubectl

• Add host entry in /etc/hosts

systemctl start Docker
swapoff /dev/centos/swap
systemctl enable kubelet.service
systemctl enable docker

echo 1 > /proc/sys/net/bridge/bridge-nf-call-iptables

useradd kubeadmin
ifdown enp0s3

NOTE: On Virtual BOX disable NAT network interface before hitting init
or else port 6443 will get bound to NAT IP
disconnect N/A from console and reboot

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

Note: If you have multiple IPs / Hostname to bind ; run following to add name/ip in certificate

kubeadm init –pod-network-cidr=10.244.0.0/16 –apiserver-advertise-address 192.168.56.240 –apiserver-cert-extra-sans kubemaster.mhn.com

Create User

su – kubeadmin

mkdir -p $HOME/.kube

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

---

Your Kubernetes master has initialized successfully!

To start using your cluster, you need to run the following as a regular user:

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

You should now deploy a pod network to the cluster.
Run “kubectl apply -f [podnetwork].yaml” with one of the options listed at:
https://kubernetes.io/docs/concepts/cluster-administration/addons/

You can now join any number of machines by running the following on each node
as root:

kubeadm join 192.168.56.240:6443 –token wxf3y9.ci2txlf7ja04svyg –discovery-token-ca-cert-hash sha256:ea3eeb5de0ffd9efe6d0f304f4fd9853c005ee98902ad7a7c110425c23eeab04

---

In order for your pods to communicate with one another, you’ll need to install pod networking. We are going to use Flannel for our Container Network Interface (CNI) because it’s easy to install and reliable. Enter this command:

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

If you see error like beow

The connection to the server localhost:8080 was refused – did you specify the right host or port?

Do the following as normal user

su – kubeadmin

sudo cp /etc/kubernetes/admin.conf $HOME/

sudo chown $(id -u):$(id -g) $HOME/admin.conf

export KUBECONFIG=$HOME/admin.conf

[root@kubmaster ~]

# kubectl apply -f https://raw.githubusercontent.com/coreos/flannel/master/Documentation/kube-flannel.yml
clusterrole.rbac.authorization.k8s.io “flannel” created
clusterrolebinding.rbac.authorization.k8s.io “flannel” created
serviceaccount “flannel” created
configmap “kube-flannel-cfg” created
daemonset.extensions “kube-flannel-ds” created

---

[kubeadmin@kubmaster ~]

$ kubectl get pods
No resources found.

[kubeadmin@kubmaster ~]

$ kubectl get pods –all-namespaces
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system etcd-kubmaster 1/1 Running 0 47m
kube-system kube-apiserver-kubmaster 1/1 Running 0 47m
kube-system kube-controller-manager-kubmaster 1/1 Running 0 47m
kube-system kube-dns-86f4d74b45-mrq4d 3/3 Running 0 1h
kube-system kube-flannel-ds-854ns 1/1 Running 0 47m
kube-system kube-proxy-rlpbc 1/1 Running 0 1h
kube-system kube-scheduler-kubmaster 1/1 Running 0 47m

[kubeadmin@kubmaster ~]

$