Service discovery in Kubernetes with Fabric8

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Service discovery in Kubernetes with Fabric8 Andy Moncsek Senior Consultant Andy.Moncsek@trivadis.

2 Service discovery in Kubernetes with Fabric8 Andy Moncsek Senior Consultant BASEL BERN BRUGG DÜSSELDORF FRANKFURT A.M. FREIBURG I.BR. GENF HAMBURG KOPENHAGEN LAUSANNE MÜNCHEN STUTTGART WIEN ZÜRICH

3 Agenda 1. Why service discovery? 2. Some Kubernetes basics 3. Service discovery in Kubernetes 4. Fabric8 & Service discovery

4 Why service discovery?

5 Why Service discovery? Dynamically assigned Dynamically changing Client / API Gatewa y :5647 7? : : Loadbalancing?

6 Client-side discovery Client knows specific service instance 3. request 2. query 1. register

7 Server-side discovery Client does not know a specific service instance 2. request 4. Loadbalance 3. query 1. register

8 Some Kubernetes basics

9 Some Kubernetes basics: What it is... Kubernetes is platform designed to automate deploying, scaling, and operating application containers. Deploy your applications quickly and predictably. Scale your applications on the fly. Roll out new features seamlessly

10 Kubernetes Namespaces virtual" cluster Separates DEV, TEST, PROD,... environments

11 Kubernetes Pods Group of containers Shares network/namespace/ IP Shares environmental variables Shared volumes

12 Kubernetes Controller Ensure X pods are running Pod templates Rolling update

13 Kubernetes Services Pod discovery IP per service 1-N port numbers Route to pods Load balancer

14 Kubernetes Services (2)

15 Kubernetes Services (3) External IP depends on: Service type = LB Infrastructure

16 Kubernetes Services (4) Cluster IP: Internal IP address Accessible by any component in namespace

17 Kubernetes Services (5) NodePort: Unique per service $NODE_IP:$NODEPORT ClusterIP references a NodePort on a specific Node

18 Kubernetes Services (6) Endpoints: 1:1 Endpoint Pod Represents the IP address of a Pod Can be queried by API

19 Service discovery in Kubernetes

20 Service discovery in Kubernetes How you can find your services in Kubernetes? Install Consul, Zookeeper,... à Out of scope ;-) Discovery using Environment variables Discovery using DNS Discovery using Kubernetes master (with Fabric8 API)

21 Service discovery in Kubernetes Discovery using Environment variables When a Pod starts, a set of env variables for each active service added {SVCNAME}_SERVICE_HOST & {SVCNAME}_SERVICE_PORT In case of many port definitions the port name is added: {SVCNAME}_SERVICE_PORT_{PORTNAME} Drawback: the Service must already exist!

22 Service discovery in Kubernetes Discovery using DNS The DNS Server watches the Kubernetes API for new Services Creates a set of DNS records for each E.g. Service: myservice, Namespace: default àmyservice.default You can access the service using: Drawback: DNS must be enabled No protocol- & port-information

23 Fabric8 & service discovery

24 Fabric8 & service discovery What is Fabric8? Fabric8 is an integrated open source DevOps and Integration Platform which works out of the box on any Kubernetes or OpenShift environment and provides Continuous Delivery, Management, ChatOps and a Chaos Monkey

25 Fabric8 & service discovery The Fabric8 kubernetes-client ( provides a Java API for working with the Kubernetes and OpenShift REST API The kubernetes-client API is used by many projects: Several discovery plugins (e.g. Hazelcast) fabric8-spring-boot ( K8sdiscovery (

26 Fabric8 & service discovery Why & When do you want to use fabric8 kubernetes-client? Discover Endpoints (Pods) for Client-side LB or monitoring Simple discovery of different ports / protocols Discovery using labels!

27 Fabric8 & service discovery - Example spec: replicas: 3 template: metadata: labels: cluster1 client. endpoints(). innamespace( hazelcas t ). withlabel( cluster1 ).lis t() client. endpoints(). innamespace( hazelcas t ). withlabel( cluster2 ).lis t()

28 Demo

29 Fabric8 & service discovery

30 Fabric8 & service discovery

31 One more thing ;-)

32 ??????

34 Discover external Services Solution: Services without selectors Service with ExternalName

35 Services without selectors kind: Service apiversion: v1 metadata: name: my-service spec: selector: app: MyApp ports: - protocol: TCP port: 80 targetport: 9376 Manually deploy kind: Endpoints apiversion: v1 metadata: name: my-service subsets: - addresses: - ip: ports: - port:

36 Service with ExternalName kind: Service apiversion: v1 metadata: name: my-service namespace: prod spec: type: ExternalName externalname: my.database.com my-service.prod.svc.cluster à CNAME = my.database.com

37 Summary Use discovery by Service name (DNS) in simple cases Use env variables for Port discovery Use Fabric8 Kubernetes-Client discovery when: Endpoint discovery needed (Client-Side discovery) Labels are working better for you Dealing with different ports Metadata is needed (monitoring)

Thank you Andy Moncsek Senior Consultant Andy.

38 Thank you Andy Moncsek Senior Consultant

39 Links

40 Kubernetes Key concept (developer view)

Introduction to Kubernetes

Introduction to Kubernetes Neil Peterson @nepeters #ITDEVCONNECTIONS Session Topics - Quick primer on containers - Container mgmt solutions - Kubernetes basics - Kubernetes deeper dive - Kubernetes beyond