Kubeadm Ansible Playbook

Build a Kubernetes cluster using Ansible with kubeadm. The goal is easily install a Kubernetes cluster on machines running:

• Ubuntu 16.04
• CentOS 7
• Debian 9

System requirements:

• Deployment environment must have Ansible 2.4.0+
• Master and nodes must have passwordless SSH access

Usage

Add the system information gathered above into a file called hosts.ini. For example:

[master]
192.16.35.12

[node]
192.16.35.[10:11]

[kube-cluster:children]
master
node

If you're working with ubuntu, add the following properties to each host ansible_python_interpreter='python3':

[master]
192.16.35.12 ansible_python_interpreter='python3'

[node]
192.16.35.[10:11] ansible_python_interpreter='python3'

[kube-cluster:children]
master
node

Before continuing, edit group_vars/all.yml to your specified configuration.

For example, I choose to run flannel instead of calico, and thus:

# Network implementation('flannel', 'calico')
network: flannel

Note: Depending on your setup, you may need to modify cni_opts to an available network interface. By default, kubeadm-ansible uses eth1. Your default interface may be eth0.

After going through the setup, run the site.yaml playbook:

$ ansible-playbook site.yaml
...
==> master1: TASK [addon : Create Kubernetes dashboard deployment] **************************
==> master1: changed: [192.16.35.12 -> 192.16.35.12]
==> master1:
==> master1: PLAY RECAP *********************************************************************
==> master1: 192.16.35.10               : ok=18   changed=14   unreachable=0    failed=0
==> master1: 192.16.35.11               : ok=18   changed=14   unreachable=0    failed=0
==> master1: 192.16.35.12               : ok=34   changed=29   unreachable=0    failed=0

The playbook will download /etc/kubernetes/admin.conf file to $HOME/admin.conf.

If it doesn't work download the admin.conf from the master node:

$ scp k8s@k8s-master:/etc/kubernetes/admin.conf .

Verify cluster is fully running using kubectl:

$ export KUBECONFIG=~/admin.conf
$ kubectl get node
NAME      STATUS    AGE       VERSION
master1   Ready     22m       v1.6.3
node1     Ready     20m       v1.6.3
node2     Ready     20m       v1.6.3

$ kubectl get po -n kube-system
NAME                                    READY     STATUS    RESTARTS   AGE
etcd-master1                            1/1       Running   0          23m
...

Resetting the environment

Finally, reset all kubeadm installed state using reset-site.yaml playbook:

$ ansible-playbook reset-site.yaml

Additional features

These are features that you could want to install to make your life easier.

Enable/disable these features in group_vars/all.yml (all disabled by default):

# Additional feature to install
additional_features:
  helm: false
  metallb: false
  healthcheck: false

Helm

This will install helm in your cluster (https://helm.sh/) so you can deploy charts.

MetalLB

This will install MetalLB (https://metallb.universe.tf/), very useful if you deploy the cluster locally and you need a load balancer to access the services.

Healthcheck

This will install k8s-healthcheck (https://github.com/emrekenci/k8s-healthcheck), a small application to report cluster status.

Utils

Collection of scripts/utilities

Vagrantfile

This Vagrantfile is taken from https://github.com/ecomm-integration-ballerina/kubernetes-cluster and slightly modified to copy ssh keys inside the cluster (install https://github.com/dotless-de/vagrant-vbguest is highly recommended)

Tips & Tricks

If you use vagrant or your remote user is root, add this to hosts.ini

[master]
192.16.35.12 ansible_user='root'

[node]
192.16.35.[10:11] ansible_user='root'