Setup k3s with Ansible

Setting up a single node k3s is very quick , takes about 2-3 minutes to setup. Setting up a k3s High Availability cluster is more complex.

Having the goal of getting a Kubernetes Lab setup quickly, the best option I had was to use Ansible. I have playbooks to setup one k3s High Availability Clusters and a single node k3s. Managing the k3s is best to be remote, to accommodate that, made the alpine1 the kubectl management server.

The most challenging task I faced when I started with kubernetes was the KUBECONFIG . Once I had this working learning the other tasks were that much easier. The Playbook and bash scripts make this easier for you.

The following describes the fastest way to setup all the servers with the required modules and k3s.

execute the playbook run from `/srv/ansible/playbook-k3s/`
ansible-playbook k3s-complete-setup.yml  --user ubuntu --ask-become-pass  -i hosts.ini

Do repeat the ansible command if there are any errors. The script should not return any errors.

Once the above update the DNS resolver to use 192.168.100.1

#on alpine1 only.
#disables readonly
chattr -i /etc/resolv.conf 

vi /etc/resolv.conf 
# remove references to other entries like 8.8.8.8

nameserver 192.168.100.1
search k8s.lab

#make file readonly
chattr +i /etc/resolv.conf 


#in my case the every time the alpine1 is rebooted the values in this file get reset.
# as such the following is to set the immutable flag 

#enables readonly
chattr +i /etc/resolv.conf 

#disables readonly
chattr -i /etc/resolv.conf 

Once the steps are completed , alpine1 can be configured to connect to the k3s clusters.

Kubeconfig on alpine1

Once the scripts 02z-k3s-copy-kubeconfig.yml and 03z-k3s-copy-kubeconfig-single.yml are completed. The playbook copy the remote kubeconfig files from the remote servers . The files will be stored in /root/.kube/clusters folder.

The ansible script k3s-complete-setup.yml will also copy the KUBECONFIG files to alpine and update ~/.kube/config to list the clusters.

We now need to have the KUBECONFIG setup on alpine . The following will merge all *.yaml files in /root/.kube/clusters

To manually setup the KUBECONFIG run this script.

 export KUBECONFIG=$(for YAML in $(find ${HOME}/.kube/clusters -name '*.yaml') ; do echo -n ":${YAML}"; done)

kubectl basic commands

Running some basic kubectl commands.

List of contexts.

(1) kubectl config get-contexts.

Change context

(2) and (4) kubectl config use-context <context name>

List kubernetes nodes

(3) and (4) kubectl get nodes

Here is a screenshot that will provide some perspective