@deepu105 @oktaDev Reactive Java Microservices on Kubernetes with Spring and JHipster Deepu K Sasidharan @deepu105 | deepu.tech 

@deepu105 @oktaDev Hi, I’m Deepu K Sasidharan JHipster co-lead developer Java Champion Creator of KDash, JDL Studio Developer Advocate @ Okta OSS aficionado, author, speaker, polyglot dev @deepu105 deepu.tech deepu105 

@deepu105 @oktaDev What is reactive programming? 

@deepu105 @oktaDev Programming using async data streams (sequence of events ordered in time) 

@deepu105 @oktaDev Reactive pros and cons ● Simple to compose data streams ● Highly interactive ● Avoid callbacks ● Ideal for large data size ● Complex to learn and implement ● Memory intensive ● Hard to debug ● Not as mature as imperative 

@deepu105 @oktaDev Options for Java ● Java Flow API ○ Introduced in java 9 ○ Provides interfaces and a simple implementation ● Reactive Extensions (RxJava) ○ Popularly known as ReactiveX ○ Provide API for async programming with observable streams ○ Available for multiple programming languages and platforms ● Project Reactor ○ Based on the reactive streams specification ○ Targeted towards building non-applications on the JVM ○ Foundation of the reactive stack in the Spring ecosystem 

@deepu105 @oktaDev Spring Boot for Reactive 

@deepu105 @oktaDev 

@deepu105 @oktaDev Spring MVC vs Spring WebFlux 

@deepu105 @oktaDev Spring MVC controller code 

@deepu105 @oktaDev Spring WebFlux controller code 

@deepu105 @oktaDev Do you always need reactive programming? 

@deepu105 @oktaDev JHipster 

@deepu105 @oktaDev JHipster in a nutshell ● Most popular Rapid Application Development platform for Java ● Scaffold modern web applications, api applications and microservices ● Scaffold CRUD entities, CI/CD, Kubernetes, Docker and so on ● 19k+ stars, 40k projects and 600+ contributors on GitHub ● 2M+ installations & 20k+ app generations per month ● Available as Yeoman based Node.js CLI and as an online web application ○ npm install -g generator-jhipster ○ Or, start.jhipster.tech 

@deepu105 @oktaDev Why JHipster? ● Developer experience oriented ● Production grade code quality (Look at the sonar scores) ○ ● Best practices on the combinations selected ● Fully working CRUD apps out of the box ● Production grade security ● You would only have to do business logic code and UX design 

@deepu105 @oktaDev JHipster microservice architecture 

@deepu105 @oktaDev Architecture 

@deepu105 @oktaDev Spring Cloud Gateway 

@deepu105 @oktaDev Spring Cloud Gateway + OIDC 

@deepu105 @oktaDev Do you need microservices? 

@deepu105 @oktaDev Demo time 

@deepu105 @oktaDev Prerequisite - Cluster Create GCP Project : $ gcloud projects create jhipster-demo - Enable billing $ gcloud config set project jhipster-demo $ gcloud services enable container.googleapis.com Create GKE Cluster : $ gcloud container clusters create hello-hipster \ --num-nodes 4 \ --machine-type n1-standard-2 Set Credentials: $ gcloud container clusters get-credentials hello-hipster 

@deepu105 @oktaDev JDL JHipster Domain Language JDL : https://bit.ly/ms-reactive $ jhipster download microservice-ecommerce-reactive Reference : https://www.jhipster.tech/jdl/ Studio : https://start.jhipster.tech/jdl-studio/ Samples : https://github.com/jhipster/jdl-samples 

@deepu105 @oktaDev JHipster magic $ jhipster jdl microservice-ecommerce-reactive --fork 

@deepu105 @oktaDev Build & Push images $ ./gradlew bootJar -Pprod jib -Djib.to.image=deepu105/store $ ./gradlew bootJar -Pprod jib -Djib.to.image=deepu105/invoice $ ./gradlew bootJar -Pprod jib -Djib.to.image=deepu105/product $ ./gradlew bootJar -Pprod jib -Djib.to.image=deepu105/notification 

@deepu105 @oktaDev Okta OIDC integration ● Install Okta CLI from cli.okta.com ● If you don't have an Okta developer account, run okta register else run okta login ● cd store && okta apps create jhipster Accept default values ● Update kubernetes/registry-k8s/jhipster-registry.yml to add oauth2 profile to SPRING_PROFILES_ACTIVE env variable ● Update kubernetes/registry-k8s/application-configmap.yml 

@deepu105 @oktaDev Okta OIDC integration data: application.yml: |- ... spring: security: oauth2: client: provider: oidc: issuer-uri: https:///oauth2/default registration: Oidc: client-id: client-secret: # plaintext secret :( 

@deepu105 @oktaDev Deploy to GKE $ cd kubernetes $ ./kubectl-apply.sh -f $ watch kubectl get pods -n jhipster \ or use KDash 😉 (brew install kdash-rs/kdash/kdash) 

@deepu105 @oktaDev Encrypt secrets ● Generate an encrypt key -> uuid | base64 ● Update kubernetes/registry-k8s/jhipster-registry.yml to add a secret and ENCRYPT_KEY environment variable ● ./kubectl-apply.sh -f ● kubectl port-forward svc/jhipster-registry -n jhipster 8761 ● Update kubernetes/registry-k8s/application-configmap.yml 

@deepu105 @oktaDev JHipster Registry 

@deepu105 @oktaDev Store Gateway 

@deepu105 @oktaDev Additional resources ● https://developer.okta.com/blog/2021/06/01/kubernetes-spring-boot-jhipster ● https://developer.okta.com/blog/2020/05/04/spring-vault ● https://www.youtube.com/watch?v=zGpnIhRgMaM ● https://developer.okta.com/blog/2022/06/09/cloud-native-java-microservices- with-istio 

@deepu105 @oktaDev Main website https://jhipster.tech JHipster online https://start.jhipster.tech GitHub https://github.com/jhipster/generator-jhipster Twitter https://twitter.com/java_hipster Stack Overflow https://stackoverflow.com/questions/tagged/jhipster?sort=newest More information on JHipster 

@deepu105 @oktaDev Thank You Deepu K Sasidharan @deepu105 | deepu.tech https://deepu.tech/tags#java