Create Kubernetes Cluster Using Kubeadm

• 3 nodes (1 master, 2 workers) : Ubuntu 18.04, 4GB RAM and 2 vCPUs
• Kubernetes v1.17.0
• Docker v19.03
• Ansible v2.10.3

Prerequisites:

• Three servers running Ubuntu 18.04 with at least 2GB RAM and 2 vCPUs each. You should be able to SSH into each server as the root user with your SSH key pair. 1 master and 2 workers
• Ansible installed on your local machine.
• git clone https://github.com/MidoAhmed/kube-cluster.git ~/kube-cluster

Steps:

1. Creating a Non-Root User on All Remote Servers :

   • execute the playbook by locally running

   $ ansible-playbook -i ~/kube-cluster/ansible/hosts.ini ~/kube-cluster/ansible/playbooks/initial.yml

2. Installing Kubernetetes’ Dependencies

   • execute the playbook by locally running

   $ ansible-playbook -i ~/kube-cluster/ansible/hosts.ini ~/kube-cluster/ansible/playbooks/kube-dependencies.yml

   • Installs Docker, the container runtime.
   • Installs apt-transport-https, allowing you to add external HTTPS sources to your APT sources list.
   • Adds the Kubernetes APT repository’s apt-key for key verification.
   • Adds the Kubernetes APT repository to your remote servers’ APT sources list.
   • Installs kubelet and kubeadm.
   • Installs kubectl on your master node.

All system dependencies are now installed :)

3. Setting Up the Master Node

   • execute the playbook by locally running

   $ ansible-playbook -i ~/kube-cluster/ansible/hosts.ini ~/kube-cluster/ansible/playbooks/master.yml

   • Verification: Check the status of the master node

   $ ssh ubuntu@master_ip
   $ kubectl get nodes

You should see that the master in a Ready state, if it is smile ;)

4. Setting Up the Worker Nodes

   • execute the playbook by locally running

   $ ansible-playbook -i ~/kube-cluster/ansible/hosts.ini ~/kube-cluster/ansible/playbooks/workers.yml

your cluster is now fully set up and functional, with workers ready to run workloads.

5. Verifying the Cluster

   • let’s verify that the cluster is working as intended.

   $ ssh ubuntu@master_ip
   $ kubectl get nodes

   NAME	STATUS	ROLES	AGE	VERSION
   instance01	Ready	master	3h4m	v1.17.0
   instance02	Ready	none	4m26s	v1.17.0
   instance03	Ready	none	31s	v1.17.0

Now that your cluster is verified successfully,

Test Access via kubectl from your machine:

# ssh to master node and copy the following conent which is the kubeconfig for your cluster.
> $ cat /etc/kubernetes/admin.conf or cat ~/.kube/config

# make sure that the server endpoint is accessible, if not like in example.kubeconfig file then replace it with public accessible ip
server: https://10.0.4.4:6443  ---> server: https://master-public-ip:6443

# set kubeconfig
> $ export KUBECONFIG=kubeconfig.yml or put in ~/.kube/config

# verifying kubectl configuration
> $ kubectl cluster-info  --insecure-skip-tls-verify

    Kubernetes master is running at https://master-public-ip:6443
    KubeDNS is running at https://master-public-ip:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

So congratulations you can access your kubernetes cluster

issues and troubleshooting:

1. first issue
   • Step: [4. Setting Up the Worker Nodes]
   • Error: kubernetes - Couldn't able to join master node - error execution phase preflight: couldn't validate the identity of the API Server
   • workaround:
     • create vnet peering between master and worker 1
     • create vnet peering between master and worker 2
     • verify by ping between nodes, make sure that ICMP protocol is activated on each machine https://docs.microsoft.com/fr-fr/azure/virtual-network/tutorial-connect-virtual-networks-portal

Resources:

• https://www.digitalocean.com/community/tutorials/how-to-create-a-kubernetes-cluster-using-kubeadm-on-ubuntu-18-04#step-2-%E2%80%94-creating-a-non-root-user-on-all-remote-servers
• https://jhooq.com/14-steps-to-install-kubernetes-on-ubuntu-18-04-and-16-04/