5 less than K8S = K3S Lightweight Kubernetes

5 less than K8S = K3S Lightweight Kubernetes
Installing and configure a Lightweight Kubernetes cluster.

This is a Lightweight Kubernetes distribution for production workloads.

You can complete the Kubernetes installation in less than 5 Minutes

Document for reference: https://rancher.com/docs/k3s/latest/en/installation/install-options/server-config/


Installation Steps:

Master : curl -sfL https://get.k3s.io | sh -
Worker : curl -sfL https://get.k3s.io | K3S_URL=https://myserver:6443 K3S_TOKEN=mynodetoken sh -

Here I am taking 1GB RAM Master and Worker Node(Ubuntu18) in my Virtual Box, The main advantage for the installation is there are no Pre-requisites.

Properties:

- You can install in Raspberry Pi Hardware
- By default, the data is keeping in SQLite no ETCD, But you can configure
- It is using Flannel network
- It is using Containerd not Docker
- Just needs Linux Kernel and Cgroup

Master Node:
==============

root@master:/home# curl -sfL https://get.k3s.io | INSTALL_K3S_EXEC="--node-ip=Master_IP --flannel-iface=enp0s8" sh -
[INFO]  Finding release for channel stable
[INFO]  Using v1.17.4+k3s1 as release
[INFO]  Downloading hash https://github.com/rancher/k3s/releases/download/v1.17.4+k3s1/sha256sum-amd64.txt
[INFO]  Downloading binary https://github.com/rancher/k3s/releases/download/v1.17.4+k3s1/k3s
[INFO]  Verifying binary download
[INFO]  Installing k3s to /usr/local/bin/k3s
[INFO]  Creating /usr/local/bin/kubectl symlink to k3s
[INFO]  Creating /usr/local/bin/crictl symlink to k3s
[INFO]  Creating /usr/local/bin/ctr symlink to k3s
[INFO]  Creating killall script /usr/local/bin/k3s-killall.sh
[INFO]  Creating uninstall script /usr/local/bin/k3s-uninstall.sh
[INFO]  env: Creating environment file /etc/systemd/system/k3s.service.env
[INFO]  systemd: Creating service file /etc/systemd/system/k3s.service
[INFO]  systemd: Enabling k3s unit
Created symlink /etc/systemd/system/multi-user.target.wants/k3s.service → /etc/systemd/system/k3s.service.
[INFO]  systemd: Starting k3s
root@master:/home#


root@master:/home# kubectl get nodes
NAME         STATUS   ROLES    AGE     VERSION
master  Ready    master   9m27s   v1.17.4+k3s1
root@master:/home/#

Kuberctl is installed by Racher script
root@msater:/home# which kubectl
/usr/local/bin/kubectl

root@master:/var/lib# cd /var/lib/rancher/
root@master:/var/lib/rancher# ls
k3s

root@master:/var/lib/rancher# cd /etc/rancher/
root@master:/etc/rancher# ls
k3s  node

root@master:/etc/rancher# cd /var/lib/rancher/k3s/server/
root@master:/var/lib/rancher/k3s/server# ls
cred  db  kine.sock  manifests  node-token  static  tls  token

TOCKEN LOCATION:
root@master:/var/lib/rancher/k3s/server# cat token
K10e08a165e58554e19bf1f0eab12dd06e8345655b7efe52bcd04029a76226b2034::server:5d82295abb1eb943c32bbcd1fec959d3

KUBE-CONFIG FILE LOCATION:
root@master:~# cd /etc/rancher/k3s/
root@master:/etc/rancher/k3s# ls
k3s.yaml


WORKER NODE Installation:
=========================

curl -sfL https://get.k3s.io | INSTALL_K3S_EXEC="--node-ip=Master_IP --flannel-iface=enp0s8" K3S_URL="https://Master_IP:6443" K3S_TOKEN="xxxxxxxxxxx034::server:5d82295abxxxxxxxc959d3" sh -


vagrant@worker:~$ sudo su
root@worker:/home# curl -sfL https://get.k3s.io | INSTALL_K3S_EXEC="--node-ip=Master_IP --flannel-iface=enp0s8" K3S_URL="https://Master_IP:6443" K3S_TOKEN="K1xxx6b2034::server:5xxxxxxx59d3" sh -
[INFO]  Finding release for channel stable
[INFO]  Using v1.17.4+k3s1 as release
[INFO]  Downloading hash https://github.com/rancher/k3s/releases/download/v1.17.4+k3s1/sha256sum-amd64.txt
[INFO]  Downloading binary https://github.com/rancher/k3s/releases/download/v1.17.4+k3s1/k3s
[INFO]  Verifying binary download
[INFO]  Installing k3s to /usr/local/bin/k3s
[INFO]  Creating /usr/local/bin/kubectl symlink to k3s
[INFO]  Creating /usr/local/bin/crictl symlink to k3s
[INFO]  Creating /usr/local/bin/ctr symlink to k3s
[INFO]  Creating killall script /usr/local/bin/k3s-killall.sh
[INFO]  Creating uninstall script /usr/local/bin/k3s-agent-uninstall.sh
[INFO]  env: Creating environment file /etc/systemd/system/k3s-agent.service.env
[INFO]  systemd: Creating service file /etc/systemd/system/k3s-agent.service
[INFO]  systemd: Enabling k3s-agent unit
Created symlink /etc/systemd/system/multi-user.target.wants/k3s-agent.service → /etc/systemd/system/k3s-agent.service.
[INFO]  systemd: Starting k3s-agent
root@worker:/home#


After this, you can see your new worker node is added into your Kubernetes cluster.
root@master:/etc/rancher/k3s# kubectl get nodes
NAME         STATUS   ROLES    AGE   VERSION
worker   Ready       39s   v1.17.4+k3s1
master   Ready    master   27m   v1.17.4+k3s1
root@master:/etc/rancher/k3s#


So we have completed the cluster installation.


For testing, we can deploy an Nginx application and check the cluster further.


root@master:/etc/rancher/k3s# kubectl get all
NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.43.0.1            443/TCP   29m


root@master:/etc/rancher/k3s# kubectl run urolime --image nginx
kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.
deployment.apps/urolime created
root@master:/etc/rancher/k3s#


root@master:/etc/rancher/k3s# kubectl get all
NAME                           READY   STATUS              RESTARTS   AGE
pod/urolime-5b47968689-f4qnj   0/1     ContainerCreating   0          26s

NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.43.0.1            443/TCP   32m

NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/urolime   0/1     1            0           26s

NAME                                 DESIRED   CURRENT   READY   AGE
replicaset.apps/urolime-5b47968689   1         1         0       26s
root@master:/etc/rancher/k3s#


Expose the service into a NodePort and try accessing it.

root@master:/etc/rancher/k3s# kubectl expose deployment urolime --port 80 --type NodePort
service/urolime exposed
root@master:/etc/rancher/k3s# kubectl get svc
NAME         TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE
kubernetes   ClusterIP   10.43.0.1              443/TCP        33m
urolime      NodePort    10.43.143.95           80:32623/TCP   7s
root@master:/etc/rancher/k3s#


root@master:/etc/rancher/k3s# curl Master_IP:32623

Welcome to nginx!

If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.

For online documentation and support please refer to
nginx.org.
Commercial support is available at
nginx.com.

Thank you for using nginx.


root@master:/etc/rancher/k3s#