kubernetes

kubernetes usage

personal cheat sheet, remember the steps.. Used with java, micronaut, gradle, docker, local kubernetes in docker edge.

build app

build library (hier: micronaut rest service mit gradlew build), port 8080.

build docker image

docker (build image)

edit dockerfile
create docker image docker build -t sample .
list images docker images

deploy on kubernetes

kubernetes (deploy)

edit kubernetes deploy yaml file
deploy on kubernetes with
- new kubectl create -f kubernetes-deploy.yaml
- update kubectl apply -f kubernetes-deploy.yaml
check deployment kubectl get deployments
check services kubectl get services
check pods kubectl get pods
check logs kubectl logs sample-frontend-5d56d95f94-7kv8w
test access wget localhost:32704/hello (see port listed with get services command)
delete
- kubectl delete deployment sample-frontend-deployment
- kubectl delete service sample-frontend

access shortcut (not using service definition)

shortcut: kubectl port-forward sample-frontend-5d56d95f94-7kv8w 8080:8080

manage deployed service

dashboard

Figure 1. kubernetes dashboard

shell access

shell on alpine image (busybox)

kubectl exec -it sample-frontend-deployment-64f4bdccd4-qkxvz -- /bin/ash

configuration examples

application.properties micronaut rest service

micronaut:
    server:
        port: 8080

DOCKERFILE

FROM openjdk:8u171-alpine3.7
RUN apk --no-cache add curl
COPY build/libs/*-all.jar sample.jar
CMD java ${JAVA_OPTS} -jar sample.jar

kubernetes-deploy.yaml

apiVersion: v1
kind: Service
metadata:
  name: sample-frontend
spec:
  type: NodePort
  selector:
    app: sample-frontend-deployment
  ports:
  - protocol: TCP
    port: 8080
    name: http
  selector:
    app: sample-frontend-deployment
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: sample-frontend-deployment
spec:
  selector:
      matchLabels:
        app: sample-frontend-deployment
  replicas: 1
  template:
    metadata:
      labels:
        app: sample-frontend-deployment
    spec:
      containers:
        - name: sample-frontend
          image: sample:latest
          imagePullPolicy: Never
          ports:
            - containerPort: 8080

running service on kubernetes

>kubectl get services
NAME              TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
kubernetes        ClusterIP   10.96.0.1       <none>        443/TCP          1d
sample-frontend   NodePort    10.103.132.72   <none>        9090:31353/TCP   12s