start.spring.io app dockerize + k8s workshop

0_pre.sh

gcloud auth login
gcloud container clusters get-credentials k8s-ws-6 --zone europe-west1-b --project k8s-ws-7
gcloud auth configure-docker
kubectl version
kubectl get nodes
kubectl create namespace myname

1_0_create_java_app

1. Go to this webpage: https://start.spring.io
2. Choose these options:
- Project: Gradle Project
- Language: Java
- Spring Boot: 2.4.1
- Project metadata:
-- defaults
-- Java: 11
3. Dependecies -> Add dependencies: Spring Web, Spring Boot Actuator
4. Generate (download)
5. Unzip to a folder in your computer

1_1_Dockerfile

# Build-time image that is discarded
FROM gradle:6.7.1-jdk11 AS build
WORKDIR /app
COPY src /app/src
COPY build.gradle /app
RUN gradle clean build bootJar
RUN ls -l /app/build/libs

FROM adoptopenjdk/openjdk11-openj9:jdk-11.0.1.13-alpine-slim
COPY --from=build /app/build/libs/app-0.0.1-SNAPSHOT.jar demo.jar
# We add curl just for testing purposes
RUN apk --no-cache add curl
ENV JAVA_OPTS=""
CMD exec java $JAVA_OPTS -jar demo.jar
EXPOSE 8080

1_2_build.sh

#!/bin/sh -e
# How to build the docker image
# NB! Change myname to your name
docker build -t myname:latest .
# How to locally run the docker
docker run --name myname -p 8080:8080 myname:latest
# Open browser localhost:8080/actuator/health
# Tag the image to be able to push it
docker tag myname:latest eu.gcr.io/k8s-ws-7/myname:1
# Send the docker image to docker repository
docker push eu.gcr.io/k8s-ws-7/myname:1

2_1_deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: demo
spec:
  replicas: 1
  strategy:
    type: RollingUpdate
    rollingUpdate:
      maxSurge: 1
  selector:
    matchLabels:
      app: demo
  template:
    metadata:
      labels:
        app: demo
    spec:
      containers:
      - image: eu.gcr.io/k8s-ws-7/mikk1:3
        resources:
          limits:
            cpu: 1000m
            memory: 1000Mi
          requests:
            cpu: 100m
            memory: 600Mi
        name: demo
        env:
          - name: SPRING_PROFILES_ACTIVE
            value: STAGING
          - name: JAVA_OPTS
            value: -Xmx256m -Xms256m
        ports:
        - containerPort: 8080
        readinessProbe:
          httpGet:
            path: /actuator/health
            port: 8080
        livenessProbe:
          httpGet:
            path: /actuator/health
            port: 8080
          initialDelaySeconds: 100

2_2_kubecommands.sh

kubectl get nodes
kubectl get namespaces
# Set kubectl against certain namespace (default ns is the default, but we want to deploy to your own ns)
kubectl config set-context $(kubectl config current-context) --namespace=myname
kubectl get pods
# This will tell the kubernetes to create the manifest
# NB! Replace image to your own. But mine will work as well.
kubectl apply -f deployment.yaml
kubectl get pods
kubectl describe pod podname
kubectl logs podname
kubectl delete pod podname
kubectl get pods
kubectl edit deployment demo
#set replicas: 2
kubectl get pods

3_1_service.yaml

apiVersion: v1
kind: Service
metadata:
  name: demo
spec:
  type: NodePort
  ports:
  - port: 80
    targetPort: 8080
    protocol: TCP
    name: http
  selector:
    app: demo

3_2_kubeservicecommands.sh

kubectl apply -f service.yaml
# Check which services you have now
kubectl get svc
# Check the details of that service
kubectl describe svc demo
# Check the ip of your pod
kubectl get pods -o wide
# "log in" to the running container
kubectl exec -it podname -- /bin/sh
# How to access your running java app inside the container
curl localhost:8080/actuator/health
# How service is accessing your pod, note the port of 8080 (theoretical, usually you don't need the pod ip at all)
curl podip:8080/actuator/health
# How to access your java app via service ip (not via DNS)
curl svc-cluster-ip/actuator/health
# How to access a service in your own namespace (DNS)
curl demo/actuator/health
# How to access a service in any namespace (DNS)
curl demo.mikk.svc.cluster.local/actuator/health

4_1_ingress.yaml

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: demo
spec:
  rules:
    - http:
        paths:
          - path: /*
            backend:
              serviceName: demo
              servicePort: http

4_2_kubeingresscommands.sh

kubectl apply -f ingress.yaml
kubectl get ingress
kubectl describe ingress demo
# open browser or curl with ip/actuator/health

5_1_autoscaler.yaml

apiVersion: autoscaling/v2beta1
kind: HorizontalPodAutoscaler
metadata:
  name: demo
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: demo
  minReplicas: 1
  maxReplicas: 3
  metrics:
  - type: Resource
    resource:
      name: cpu
      targetAverageUtilization: 100

5_2_commands.txt

kubectl apply -f autoscaler.yaml
kubectl top pods
# Check deployment resources.requests. Autoscaler works on comparing actual (from kubectl top pods) usage to request.
# Run load test to check how autoscaler will scale your pod
# Check the content in zalando files, change target url to your ingress public ip
bash <(curl -s https://raw.githubusercontent.com/zalando-incubator/docker-locust/master/local.sh) deploy --target=http://34.102.186.215/actuator/health --locust-file=https://raw.githubusercontent.com/zalando-incubator/docker-locust/master/example/simple.py --slaves=4 --mode=manual
# Open browser at localhost:8089 to run the load test

6_1_some.conf

test=1
props=2

6_2_commands.sh

kubectl create configmap demo --from-file=some.conf
kubectl get configmaps
kubectl describe configmap demo

6_3_deployment.yaml

# Edit your previous deployment.yaml and volumeMounts to the end
        livenessProbe:
          httpGet:
            path: /actuator/health
            port: 8080
          initialDelaySeconds: 100
        volumeMounts:
          - mountPath: /conf
            name: conf
      volumes:
        - name: conf
          configMap:
            name: demo
            items:
              - key: some.conf
                path: some.conf

6_4_commands.sh

kubectl apply -f deployment.yaml
kubectl get pods
# Check for new pods
kubectl exec -it podname -- /bin/sh
ls /conf
cat /conf/some.conf