kubernetes_demo_project

A java application having a tomcat webserver and mysql database pods using namespace, configMap, secret, persistentVolume, service, label, selector and replicaset.

Pre-requisites:

1. Install 'kubectl'
2. Install 'minikube'
3. Before working on this project make sure you have setup single node cluster and it is running.

Pod creation & project setup

Go to the directory where you have kept all your yaml files.

1. 1st create the images out of the Dockerfiles Dockerfile-mysql & Dockerfile-tomcat.

docker build -t mysql:1.1 /path/to/dockerfile/Dockerfile-mysql .
docker build -t loginwebapp:1.2 /path/to/dockerfile/Dockerfile-tomcat .

2. Create a namespace where you want to run your pod

kubectl create -f namespaceDefinition.yml

3. Create configMap

kubectl create -f configmap-mysql.yml

4. Create secret to secure the DB credentials

kubectl create -f secret-mysql.yml

5. Create persistent volume and persistent volume claim

kubectl create -f mysql-pv.yml

6. Now create pods using replicaset Note: The service and replicaset are added in one yaml file

kubectl create -f replicasetDefinition-tomcat.yml
kubectl create -f replicasetDefinition-mysqldb.yml

At this point your pods will be up and running.

Check pods and the services.

Ranjits-MacBook-Air:Desktop ranjitswain$ kubectl get all --namespace=dev
NAME                             READY   STATUS    RESTARTS   AGE
pod/mysqldb-replicaset-w5tgg     1/1     Running   6          6d12h
pod/tomcatweb-replicaset-kn8bz   1/1     Running   6          6d12h
pod/tomcatweb-replicaset-tdj4q   1/1     Running   6          6d12h

NAME                      TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)          AGE
service/mysqldb-service   ClusterIP   None             <none>        3306/TCP         6d12h
service/tomcat-service    NodePort    10.105.128.104   <none>        8080:30008/TCP   6d12h

NAME                                   DESIRED   CURRENT   READY   AGE
replicaset.apps/mysqldb-replicaset     1         1         1       6d12h
replicaset.apps/tomcatweb-replicaset   2         2         2       6d12h

To check configMap

Ranjits-MacBook-Air:Desktop ranjitswain$ kubectl get configmap --namespace=dev
NAME        DATA   AGE
db-config   3      8d

To check secret

Ranjits-MacBook-Air:Desktop ranjitswain$ kubectl get secret --namespace=dev
NAME                  TYPE                                  DATA   AGE
db-secret             Opaque                                2      9d
default-token-99hkl   kubernetes.io/service-account-token   3      10d

Persisten Volume

Ranjits-MacBook-Air:Desktop ranjitswain$ kubectl get pv --namespace=dev
NAME              CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                STORAGECLASS   REASON   AGE
mysql-pv-volume   2Gi        RWO            Retain           Bound    dev/mysql-pv-claim   manual                  8d

Persistent Volume Claim

Ranjits-MacBook-Air:Desktop ranjitswain$ kubectl get pvc --namespace=dev
NAME             STATUS   VOLUME            CAPACITY   ACCESS MODES   STORAGECLASS   AGE
mysql-pv-claim   Bound    mysql-pv-volume   2Gi        RWO            manual         8d

Check the pods

Ranjits-MacBook-Air:Desktop ranjitswain$ kubectl get pods --namespace=dev
NAME                         READY   STATUS    RESTARTS   AGE
mysqldb-replicaset-w5tgg     1/1     Running   6          6d12h
tomcatweb-replicaset-kn8bz   1/1     Running   6          6d12h
tomcatweb-replicaset-tdj4q   1/1     Running   6          6d12h

Check the services

Ranjits-MacBook-Air:Desktop ranjitswain$ kubectl get services --namespace=dev
NAME              TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)          AGE
mysqldb-service   ClusterIP   None             <none>        3306/TCP         6d12h
tomcat-service    NodePort    10.105.128.104   <none>        8080:30008/TCP   6d12h

Note: Here the namespace was create as dev. So you need to specify the namespace name while diplaying the details.

To view the application in your web browser, describe the service and get the LoadBalancer Ingress name and the NodePort

Ranjits-MacBook-Air:Desktop ranjitswain$ kubectl describe service tomcat-service --namespace=dev
Name:                     tomcat-service
Namespace:                dev
Labels:                   <none>
Annotations:              <none>
Selector:                 app=tomcatwebapp,type=front-end
Type:                     NodePort
IP:                       10.101.111.123
LoadBalancer Ingress:     localhost
Port:                     <unset>  8080/TCP
TargetPort:               8080/TCP
NodePort:                 <unset>  30008/TCP
Endpoints:                10.1.1.15:8080,10.1.1.17:8080
Session Affinity:         None
External Traffic Policy:  Cluster
Events:                   <none>

i.e. http://localhost:30008/LoginWebApp/

LoginWebApp is your application name.