spring-boot-kubernetes

Create Dockerfile

FROM openjdk:8-jdk-alpine
MAINTAINER Phea Soy
VOLUME [ "/tmp" ]
COPY  target/spring-boot-kubernetes-0.0.1-SNAPSHOT.jar app.jar
EXPOSE 9977
ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app.jar"]

Build image

$ docker build -t spring-boot-k8s:v1 .

Install minikube for single cluster

• This is the official document - minikube-install

Start minikube

$ minikube start

Set docker to use minikube daemon

$ eval $(minikube docker-env)

Create Deployment

$ kubectl run spring-boot-k8s --image=spring-boot-k8s:v1 --port=9977

Get POD

$ kubectl get pod

Watch pod status

$ kubectl get pod -w

Switch

Create namespace

apiVersion: v1
kind: Namespace
metadata: 
  name: example-k8s

• Create create-namespace.yml

$ kubectl create -f k8s/create-namespace.yml

Get namespace

$ kubectl get ns

Switch namespace

$ kubectl config set-context minikube --namespace example-k8s

• You can also install kubens

$ kubens example-k8s

Describe namespace

$  kubectl describe ns example-k8s

Delete namespace

$ kubectl delete namespaces example-k8s

Create ResourceQuota

• Create create-resource-quota.yaml

apiVersion: v1
kind: ResourceQuota
metadata:
  name: resource-quota-mem-cpu-example
  namespace: example-k8s
spec:
  hard: 
    requests.cpu: "1"
    requests.memory: 1Gi
    limits.cpu: "2"
    limits.memory: 4Gi

$ kubectl create -f k8s/create-resource-quota.yaml 

• Get the resource

$ kubectl describe ns example-k8s

• ===>

Name:		example-k8s
Labels:		app=spring-boot
Annotations:	<none>
Status:		Active

Resource Quotas
 Name:			resource-quota-mem-cpu-example
 Resource		Used	Hard
 --------		---	---
 limits.cpu		0	2
 limits.memory		0	4Gi
 requests.cpu		0	1
 requests.memory	0	1Gi

Create Deployment

• Create create-deployment.yaml file

kind: Deployment
apiVersion: extensions/v1beta1
metadata:
  name:   spring-boot-k8s-deployment
  labels:
    app: spring-boot-k8s
  namespace: example-k8s
spec:
  replicas: 1
  selector:
    matchLabels:
      app: spring-boot-k8s
  template:
    metadata:
      labels:
        app: spring-boot-k8s
    spec:
      containers:
      - name: spring-boot-k8s
        image: spring-boot-k8s:v1
        ports:
        - containerPort: 9977
        resources:
          limits:
            memory: "1Gi"
            cpu: "500m"
          requests: 
            memory: "256Mi"
            cpu: "200m"
        livenessProbe:
          httpGet:
            path: /actuator/health/liveness
            port: 9977
          initialDelaySeconds: 60
          periodSeconds: 5
        readinessProbe:
          httpGet:
            path: /actuator/health/readiness
            port: 9977
          initialDelaySeconds: 60
          timeoutSeconds: 5

$ kubectl create -f k8s/create-deployment.yaml

Scale deployment

$ kubectl scale deployment spring-boot-k8s-deployment --replicas=2

Update deployment

 kubectl set image deployment/spring-boot-k8s-deployment spring-boot-k8s=spring-boot-k8s:v5 --record

Expose service for deployment

$ kubectl expose deployment spring-boot-k8s-deployment --name=spring-boot-service --type=NodePort

Get the URL of the expose service

$ minikube service spring-boot-service -n example-k8s --url

Access the application

$ curl http://192.168.64.2:32352/k8s/sidara

• Response

HTTP/1.1 200 
Content-Type: text/plain;charset=UTF-8
Content-Length: 62
Date: Sun, 01 Sep 2019 05:48:36 GMT
Hi sidara- I am a SpringBoot Application run inside Kubernetes

Delete service

$ kubectl delete service spring-boot-k8s

Create service access outside the cluster

• Create create-service.yaml file

apiVersion: v1
kind: Service
metadata:
  labels:
    app: spring-boot-k8s-service
  name: spring-boot-k8s-service
  namespace: example-k8s
spec:
  ports:
  - nodePort: 30001 # Port access outside the cluster
    port: 9977 # Port access inside the cluster
    protocol: TCP
    targetPort: 9977 # Port forward to inside the port which container running
  selector:
    app: spring-boot-k8s
  type: NodePort

$ kubectl create -f k8s/create-service.yaml

Access The Application

$  curl http://$(minikube ip):30001/k8s/dara

Create ConfigMap

$ kubectl create configmap spring-boot-k8s --from-file k8s/user.properties