Tomcat on a Single Instance of K3S

December 27, 2022

If Installing in CentOS or REL

It is recommended to turn off firewalld or you cant have other Worker Nodes

sudo systemctl disable firewalld --now

Make Single Node K3S

This will be the Master Node if you add more worker nodes

run this command

curl -sfL https://get.k3s.io | sh -

https://stackoverflow.com/questions/51717422/ip-deployment-tomcat-kubernetes

Deploy Tomcat on Kubernetes

create manifest file

nano manifest_file.yaml

edit Manifest file:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: tomcat-pod
spec:
  selector:
    matchLabels:
      run: tomcat-pod
  replicas: 1
  template:
    metadata:
      labels:
        run: tomcat-pod
    spec:
      containers:
      - name: tomcat
        image: tomcat:latest
        ports:
        - containerPort: 8080

apply manifest file

kubectl apply -f manifest_file.yaml

create service.yaml

nano service.yaml

add this content

apiVersion: v1
kind: Service
metadata:
  name: tomcat-pod
  labels:
    run: tomcat-pod
spec:
  type: NodePort
  ports:
  - port: 8080
    targetPort: 8080
  selector:
    run: tomcat-pod

apply service

kubectl apply -f service.yaml

kubectl get all
kubectl get endpoints

you should get these endpoints

NAME         ENDPOINTS         AGE
kubernetes   10.0.0.154:6443   51m
tomcat-pod   10.42.0.11:8080   9m5s

Open firewall for port 8080

firewall-cmd --permanent --add-port=8080/tcp

firewall-cmd --reload

curl to endpoint in above lis of endpoints:

curl http://10.42.0.11:8080

and get

<!doctype html><html lang="en"><head><title>HTTP Status 404 – Not Found</title><style type="text/css">body {font-family:Tahoma,Arial,sans-serif;} h1, h2, h3, b {color:white;background-color:#525D76;} h1 {font-size:22px;} h2 {font-size:16px;} h3 {font-size:14px;} p {font-size:12px;} a {color:black;} .line {height:1px;background-color:#525D76;border:none;}</style></head><body><h1>HTTP Status 404 – Not Found</h1><hr class="line" /><p><b>Type</b> Status Report</p><p><b>Description</b> The origin server did not find a current representation for the target resource or is not willing to disclose that one exists.</p><hr class="line" /><h3>Apache Tomcat/10.1.1</h3></body></html>[root@instance-20221025-1846 tomcat]#

Undeploy and remove Tomcat service

kubectl delete deployment tomcat-pod
deployment.apps "tomcat-pod" deleted

kubectl delete service tomcat-pod
service "tomcat-pod" deleted
[root@instance-20221025-1846 tomcat]# kubectl get all

To destroy K3S instance

/usr/local/bin/k3s-killall.sh
/usr/local/bin/k3s-uninstall.sh

Adding a worker node

Run this command on the Master Node server to get the Token which you will use to create Worker Nodes

cat /var/lib/rancher/k3s/server/node-token

Kill and delete previous worker or master node

/usr/local/bin/k3s-killall.sh
/usr/local/bin/k3s-agent-uninstall.sh
/usr/local/bin/k3s-uninstall.sh

The Firewalls must be disabled on CentOS Master and CentOS Worker nodes

It is recommended to turn off firewalld

sudo systemctl disable firewalld --now

Create new Worker node

Assume that your Master nodes IP address is: 196.36.100.128 and that the token value you have below is what you previously got from the Master Node server.

Now run these commands every time you want to add a Worker Node from the Worker Node server.

k3s_token="K10ecd439433c394d3f4961a8180b235304b753a3f8002e15eae4b3e983326ec72e::server:de96d8e4a3d0b66e6b844e43868fec1e"
k3s_url="https://10.154.2.81:6443"
curl -sfL https://get.k3s.io | K3S_URL=${k3s_url} K3S_TOKEN=${k3s_token} sh -

Run these commands from the Master Node server to confirm the status of the Nodes and cluster

kubectl get nodes


kubectl get all -o wide