You’re a Java developer? Already familiar with Docker? Want to know more about Kubernetes and its ecosystem for developers? During this session, you’ll get familiar with core Kubernetes concepts (pods, deployments, services, volumes, and so on) before seeing the most-popular and most-productive Kubernetes tools in action, with a special focus on Java development. By the end of the session, you’ll have a better understanding of how you can leverage Kubernetes to speed up your Java deployments on-premises or to any cloud.

1. © 2018 Software AG. All rights reserved.
Anthony Dahanne
@anthonydahanne
blog.dahanne.net
October 23rd 2018
[TUT5930]
KUBERNETES
FOR JAVA DEVELOPERS

2. LET ME INTRODUCE MYSELF
„Anthony Dahanne, Software Engineer
@Terracotta, a Software AG company
„Working on Terracotta cloud deployments
(Docker, Kubernetes, AWS, etc.)
„Also working on Management and Monitoring for
Terracotta products
„Montréal JUG leader

3. AGENDA
• Containers & the JVM
• Kubernetes 101
• Tools to become a 100x developer with Kubernetes
• Integrating with Kubernetes

4. CONTAINERS IN ONE SLIDE
• Containers all use host OS kernel
• Host OS can be running in a VM or barebone
• Host OS Linux distribution does not matter
• only the kernel does !
• Isolation performed with chroot, namespaces, cgroups
• namespaces : limit what you can see
• pid, net, mnt, uts, ipc, user
• cgroups : limit what you can use
• memory, CPU, block IO, network (with iptables)
THAT’S JUST AN ISOLATED PROCESS !
https://www.slideshare.net/jpetazzo/anatomy-of-a-container-namespaces-cgroups-some-filesystem-magic-linuxcon
https://www.enterprisetech.com/2014/08/18/ibm-techies-pit-docker-kvm-bare-metal/

5. JAVA AND LINUX CONTAINERS
• The JVM “guesses” available CPU and Memory resources available on the host
• By default, uses 1/4 of the available memory
• Although it can be set manually
• -XX:ParallelGCThreads,-XX:CICompilerCount,-Xmx
• Since Java SE 8u131, the JVM
• is “Docker aware with respect to Docker CPU limits transparently”
• has new options for detecting memory limits (not transparent, yet)
• -XX:+UnlockExperimentalVMOptions
• -XX:+UseCGroupMemoryLimitForHeap
BEWARE WHAT THE JVM CAN SEE ! (AND USE !)
Since Java 10
(backported to Java 8u191 !)
the JVM properly (without -XX)
detects CPU and Memory limits
https://blog.docker.com/2018/04/improved-docker-container-integration-with-java-10/

6. Container, exposing 8080
JVM based webapp, 8080
H2 (in memory db)
Ehcache (local caching)
REST API
Angular 2 UI
BASED ON JHIPSTER / SPRING BOOT 2
DOCKERIZING THE DEMO APP

7. WE ALL KNOW DOCKER, BUT…
IS IT THE ONLY OPTION TO BUILD IMAGES AND RUN CONTAINERS ?
FROM openjdk
EXPOSE 8080
ADD app.jar /app.jar
CMD java - jar /app.jar
Linux Container
Docker / OCI Image
Data & Metadata
runbuild

8. WE ALL KNOW DOCKER, BUT…
WHAT ARE THE CONTENDERS ?
• cri-o
• rkt
(Daemonless) BUILD RUN*
Supports Dockerfile ?
IMG Yes
Buildah Yes
Bazel No (has builder for java)
Buildpack No (has builder for java)
Jib No (java native builder)
And others local (Draft), and cloud builders : DockerHub, Google Cloud Builder, etc.
*: that includes registry and storage access

9. KUBERNETES 101
A CONTAINER ORCHESTRATOR

10. KUBERNETES INTRODUCTION
• Initial release June 7th 2014
• Apache 2 License, written in Go
• heavily inspired by Borg, internal system from Google
• Currently 1.12 (a new release every 3 months on average)
• Under the umbrella of the Cloud Native Computing Foundation
• that includes Oracle, Intel, IBM, Pivotal, Redhat, etc.
• along with Prometheus, Helm, OpenTracing, containerd, CNI, Buildpacks, etc.
FROM BORG TO CNCF
https://l.cncf.io

11. KUBERNETES ARCHITECTURE
By Khtan66 - CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=53571935
MASTER NODES, WORKER NODES, SOME NETWORKING…

12. Deployment (Declarative Updates)
> kubectl set image deployment/tmc-deployment tmc=tmc:10.3
> kubectl rollout status deployment/tmc-deployment
Replica Set (Match and Scale definitions)
spec:
replicas: 3
selector:
matchLabels:
tier: tmc
KUBERNETES WORKLOADS (PODS AND CONTROLLERS)
DEPLOYMENT > REPLICA SET > POD > CONTAINER
Pod
spec:
containers:
- name: tmc
image: store/softwareag/tmc:10.2
command: [‘start.sh’]
- name: helper-container
image: busybox
command: ['sh', '-c', 'ping tmc’]
volumes: (secrets, configmaps, etc.)
hostname: terracotta
+ Jobs, StatefulSets, Daemon sets, etc.
metadata:
labels:
tier: tmc

13. KUBERNETES SERVICES (L4)
• ClusterIP (default)
• Exposes the service on a cluster-internal IP
• NodePort
• Exposes the service on a port on each node’s IP
• LoadBalancer
• Exposes the service externally,
• using the cluster provided load balancer
HOW DO YOU EXPOSE YOUR WORKLOADS
“A Kubernetes Service is an abstraction which defines a logical set of Pods and a policy by which to access them”
https://kubernetes.io/docs/concepts/services-networking/service/
Node A
Pod-1
labels
tier:frontend
Service
spec:
type: LoadBalancer
ports:
-port:80
selector:
tier:frontend
in | outside
NodeB
Pod-2
labels
tier:frontend

14. KUBERNETES VOLUMES, CONFIG MAPS AND SECRETS
• Many types of volumes are available : hostPath, nfs, cloud specific, etc.
• ConfigMaps and Secrets are stored on the Kubernetes key/value store
YOU CAN MOUNT THEM ALL !
Pod
apiVersion: v1
kind: Pod
spec:
containers:
- name: terracotta-server
image: store/softwareag/terracotta-server:10.2
volumeMounts:
- name: config-volume
mountPath: /config
- name: data
mountPath: /data
volumes:
- name: config-volume
configMap:
name: tc-config
- name: data
hostPath:
path: /usr
ConfigMap
apiVersion: v1
kind: ConfigMap
metadata:
name: tc-config
data:
tc-config.xml: |
<xml></xml>

15. KUBERNETES DEPLOYMENTS
• Cloud providers
• Google Cloud with GKE
• Microsoft Azure with AKS
• Amazon with Kops and now EKS
• Oracle Cloud with OKE
• Exoscale, Digital Ocean,OVH, etc.
• Playgrounds : Katacoda and Play with
Kubernetes
CLOUD, ON-PREMISE, LOCAL
• On-premise
• Hard way
• Kubeadm
• Local
• Minikube
• Minishift
• Docker for Mac (more on this one later)

16. Kubernetes Cluster
n
Terracotta Server
Terracotta Server…
Demo app
MySQL
DEPLOYING THE DEMO APP TO KUBERNETES

17. KUBERNETES PACKAGING : HELM
• Helm is installed on the client, Tiller is the server side
• With Helm you deploy / create Charts that are run as Releases
• In a Chart, you package your Kubernetes manifests, and your dependencies
• A very notable feature is the “templatization“ of your Kubernetes manifests
APT / YUM FOR KUBERNETES
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: {{ template "terracotta.fullname" . }}
labels:
app: {{ template "terracotta.name" . }}
spec:
replicas: {{ .Values.replicaCount }}
selector:
matchLabels:
app: {{ template "terracotta.name" . }}
serviceName: {{ template "terracotta.fullname" . }}
spec:
{{- if .Values.nodeSelector }}
nodeSelector:
{{ toYaml .Values.nodeSelector | indent 8 }}
{{- end }}
containers:
- name: {{ template "terracotta.fullname" . }}
image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}”

18. TOOLS TO BECOME A 100X DEVELOPER
WITH KUBERNETES

19. CLASSIC DOCKER AND KUBERNETES TOOLING
• IDE plugins
• auto completion for Dockerfile, Kubernetes and Helm! (IntelliJ 2018.3)
• To build and deploy images from the IDE
• Build tools (Maven / Gradle) Docker integration
• Maven Docker plugin, Jib
• Docker for Mac / Win 10
•latest stable comes with K8s support
• Minikube

20. KUBERNETES TOOLING : SKAFFOLD
• Skaffold goal is to auto re-deploy on change
• A month ago jib integration was added
• A Kubernetes manifest, a skaffold config file and skaffold dev
• watches your source files
• rebuilds them (output is a Docker image) on change
• (re) deploys your app to Kubernetes
MAGICALLY AUTO REDEPLOYS ON CHANGE
apiVersion: skaffold/v1alpha4
kind: Config
build:
artifacts:
- image: anthonydahanne/fullstack
context: .
jibMaven:
profile: "dev,skipTestsAndYarn"

21. KUBERNETES TOOLING : TELEPRESENCE
• Telepresence goal is to allow local processes to be available in a remote
Kubernetes cluster
• A process running on your laptop can access (remote) Kubernetes resources
• It can also be seen by them
• Most common use case is to replace an existing pod with the telepresence pod
that proxies both ways to your local process
MAGICALLY DEPLOY LOCAL PROCESSES INTO THE K8S CLUSTER
> telepresence
--swap-deployment fullstack
--expose 8080:80
--run java -jar target/demo-1.0.0-SNAPSHOT.war

22. INTEGRATION WITH KUBERNETES

23. MONITORING WITH PROMETHEUS
• CNCF graduated / is the basis for an open monitoring format
• By default pull metrics from apps; but a Node exporter supports push
• Extremely simple to configure for Kubernetes workloads :
• Dropwizard metrics, micrometer, etc. provide Prometheus integration for Java
MONITORING SYSTEM AND TIME SERIES DATABASE
kind: Service
metadata:
annotations:
prometheus.io/scrape: 'true'
prometheus.io/path: '/prometheusMetrics'

24. MONITORING WITH PROMETHEUS
GENERAL ARCHITECTURE
https://winderresearch.com/introduction-to-monitoring-microservices-with-prometheus/

25. KUBERNETES OPERATOR IN JAVA
• Operators (or controllers) provide better user experience for deploying and
managing complex applications like databases (PostgreSQL, Terracotta server, etc.)
• They can create and manage their own Custom Resource Definitions (CRDs)
- or provide a CLI or UI via their own REST endpoints
USING FABRIC8 OR KUBERNETES JAVA SDK
<dependency>
<groupId>io.fabric8</groupId>
<artifactId>kubernetes-client</artifactId>
<version>4.0.3</version>
</dependency>
<dependency>
<groupId>io.kubernetes</groupId>
<artifactId>client-java</artifactId>
<version>3.0.0-beta2</version>
</dependency>
Service tmcService = new ServiceBuilder()
.withNewMetadata()
.withName("tmc")
.endMetadata()
.withNewSpec()
.addNewPort()
.withName("tmc-port")
.withPort(9480)
.endPort()
.withType("LoadBalancer")
.addToSelector("app", "tmc")
.endSpec()
.build();

26. TERRACOTTA OPERATOR ARCHITECTURE
Kubernetes Cluster
Terracotta Operator
REST API
CLI / Web UI
K8S API Server
Java SDK
REST calls
license
tc-configs
operator config
Terracotta
ServerTerracotta
Server
TMC
ConfigMaps
Services,
StatefulSets
A PRIVILEGED POD THAT LISTENS TO THE USER

27. TERRACOTTA OPERATOR ARCHITECTURE
Kubernetes Cluster
Terracotta Operator
kubectl apply
K8S API Server
Java SDK
Watch
license
tc-configs
operator config
Terracotta
ServerTerracotta
Server
TMC
ConfigMaps
Services,
StatefulSets
A PRIVILEGED POD THAT LISTENS TO THE API SERVER

28. THE END ! OR JUST THE BEGINNING ?
RBAC
Service Mesh
Ingress controller
…

29. LINKS AND OTHER REFERENCES
• Containers from scratch, talk by Liz Rice
• Jib presentation, talk by Qingyang Chen and Appu Goundan
• The fullstack demo app (and its jib, kubernetes, helm, scaffold files) is on Github

30. © 2017 Software AG. All rights reserved. For internal use only
Coming up next !