Building Reactive Microservices with Kotlin & running on Kubernetes

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Sendil Kumar N & 03 Nov 2022 Building Reactive Microservices & Running on Kubernetes using KHipster @sendilkumarn

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@sendilkumarn

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Agenda • Why Microservices? • Why Kubernetes? • Why Reactive? • Why KHipster? • Demo @sendilkumarn

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Why Microservices? @sendilkumarn

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@sendilkumarn

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de-facto standard @sendilkumarn

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de-facto standard isolated & independent @sendilkumarn

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de-facto standard isolated & independent granular scalability @sendilkumarn

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de-facto standard isolated & independent granular scalability fault tolerant @sendilkumarn

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@sendilkumarn

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Does one thing & do it well @sendilkumarn

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Does one thing & do it well Should avoid Single Point of Failure @sendilkumarn

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Why Kubernetes? @sendilkumarn

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Each service own their data @sendilkumarn

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Each service own their data @sendilkumarn

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Contracts @sendilkumarn

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Contracts @sendilkumarn

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Contracts @sendilkumarn

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@sendilkumarn

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How to know whether the service is running? @sendilkumarn

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How to know whether the service is running? How to scale the services? @sendilkumarn

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How will we know whether the service is running or not? How to know whether the service is running? How to scale the services? @sendilkumarn

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How will we know whether the service is running or not? How to know whether the service is running? How to scale the services? How to safely update a con fi g / password? @sendilkumarn

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Kubernetes Build / Deploy / Scale containerised apps @sendilkumarn

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@sendilkumarn

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How to know whether the service is running? Load Balancing & Service Discovery @sendilkumarn

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How to know whether the service is running? How to scale the services? Load Balancing & Service Discovery Automatic Scaling based on conditions @sendilkumarn

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How will we know whether the service is running or not? How to know whether the service is running? How to scale the services? Load Balancing & Service Discovery Automatic Scaling based on conditions Automated monitoring to start & stop services @sendilkumarn

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How will we know whether the service is running or not? How to know whether the service is running? How to scale the services? How to safely update a password? Load Balancing & Service Discovery Automatic Scaling based on conditions Automated monitoring to start & stop services Secret & Con fi g Management @sendilkumarn

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@sendilkumarn

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@sendilkumarn

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You just replaced function calls into network calls!! @sendilkumarn

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@sendilkumarn

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@sendilkumarn

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@sendilkumarn

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50ms @sendilkumarn

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50ms 100ms @sendilkumarn

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50ms 100ms 20ms @sendilkumarn

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50ms 100ms 20ms 170ms @sendilkumarn

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@sendilkumarn

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@sendilkumarn

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50ms 100ms 20ms @sendilkumarn

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50ms 100ms 20ms 100ms @sendilkumarn

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Non-Blocking Async communication @sendilkumarn

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@sendilkumarn

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Why Reactive? @sendilkumarn

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@sendilkumarn

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Highly interactive & fast experience @sendilkumarn

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Highly interactive & fast experience consistent & reliable experience @sendilkumarn

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Highly interactive & fast experience consistent & reliable experience Scale dynamically @sendilkumarn

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Highly interactive & fast experience consistent & reliable experience Scale dynamically Less resource utilisation @sendilkumarn

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Reactive Manifesto @sendilkumarn

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Reactive Manifesto • Responsive Always caller will receive response as fast as possible @sendilkumarn

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Reactive Manifesto • Responsive • Resilient Recovers quickly @sendilkumarn

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Reactive Manifesto • Responsive • Resilient • Elastic Delivers @ Scale @sendilkumarn

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Reactive Manifesto • Responsive • Resilient • Elastic • Message Driven Msg In Msg Out @sendilkumarn

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Reactive Manifesto • Responsive • Resilient • Elastic • Message Driven @sendilkumarn

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Everything should be reactive to reap bene fi ts of reactive system @sendilkumarn

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Not for everyone @sendilkumarn

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@sendilkumarn

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But how can we build services with RxJava? @sendilkumarn

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@sendilkumarn

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@sendilkumarn

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@PostMapping("/users") public User createUser(@Valid @RequestBody User user) { // Handle errors User result = userRepository.save(user); // do something with the result return ResponseEntity .created(new URI("/api/users/" + result.getId())) .headers(HeaderUtil.createEntityCreationAlert(...)) .body(result); } @sendilkumarn

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Spring Reactive @sendilkumarn

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@sendilkumarn

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Mono @sendilkumarn

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Mono Flow @sendilkumarn

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Mono Flow Emit 0 or 1 value @sendilkumarn

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Mono Flow Emit 0 or 1 value Emits 0 or many values @sendilkumarn

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@PostMapping(“/users") Mono public User createUser(@Valid @RequestBody User user) { // Handle errors User result = userRepository.save(user); // do something with the result return ResponseEntity .created(new URI("/api/users/" + result.getId())) .headers(HeaderUtil.createEntityCreationAlert(...)) .body(result); } @sendilkumarn

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@PostMapping(“/users") Mono public User createUser(@Valid @RequestBody User user) { // Handle errors return User result = userRepository.save(user) .flatMap(// do something with the result) .map(return ResponseEntity .created(new URI("/api/users/" + result.getId())) .headers(HeaderUtil.createEntityCreationAlert(...)) .body(result)); } @sendilkumarn

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@PostMapping("/users") public Mono createUser(@Valid @RequestBody User user) { // Handle errors return userRepository.save(user) .flatMap( // Do something with the result/users ) .map( result -> return ResponseEntity .created(new URI("/api/users/" + result.getId())) .headers(HeaderUtil.createEntityCreationAlert(...)) .body(result); ) } @sendilkumarn

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But Kotlin makes it even more sweeter… @sendilkumarn

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@PostMapping("/users") fun createUser(@Valid @RequestBody user: User) = // Handle errors userRepository.save(user) .flatMap { // Do something with the users } .map { ResponseEntity .created(URI("/api/users/${it.id}”)) .headers(HeaderUtil.createEntityCreationAlert(…)) .body(it) } @sendilkumarn

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Kotlin @sendilkumarn

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Kotlin • Null Safety @sendilkumarn

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Kotlin • Null Safety • Less verbose @sendilkumarn

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Kotlin • Null Safety • Less verbose • Co-routines @sendilkumarn

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Kotlin • Null Safety • Less verbose • Co-routines • Expressive & Concise @sendilkumarn

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Kotlin • Null Safety • Less verbose • Co-routines • Expressive & Concise • “Hacky” & Fun @sendilkumarn

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Kotlin • Null Safety • Less verbose • Co-routines • Expressive & Concise • “Hacky” & Fun Java Catching up… @sendilkumarn

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Kotlin • Null Safety • Less verbose • Co-routines • Expressive & Concise • “Hacky” & Fun Java Project Loom @sendilkumarn

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Kotlin • Null Safety • Less verbose • Co-routines • Expressive & Concise • “Hacky” & Fun Java @sendilkumarn

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Kotlin • Null Safety • Less verbose • Co-routines • Expressive & Concise • “Hacky” & Fun @sendilkumarn

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Kotlin • Null Safety • Less verbose • Co-routines • Expressive & Concise • “Hacky” & Fun Personal Preference @sendilkumarn

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Why KHipster? @sendilkumarn

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KHipster is a open source app. generator @sendilkumarn

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open source app generator development platform KHipster is @sendilkumarn

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open source app generator development platform generates all bells & whistles KHipster is @sendilkumarn

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@sendilkumarn

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npm i -g generator-jhipster-kotlin @sendilkumarn

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npm i -g generator-jhipster-kotlin mkdir app & cd app @sendilkumarn

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npm i -g generator-jhipster-kotlin mkdir app & cd app khipster @sendilkumarn

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npm i -g generator-jhipster-kotlin mkdir app & cd app khipster @sendilkumarn

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Various options • Monolithic / Microservices • Spring WebFlux / Boot • Authentication • Database • Maven / Gradle • Web Frameworks • CI & CD • Kubernetes & Istio @sendilkumarn

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Demo Time @sendilkumarn

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Recap @sendilkumarn

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Recap • Microservices splitting your services enable you to scale faster @sendilkumarn

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Recap • Microservices • Kubernetes splitting your services enable you to scale faster super power to manage & maintain your services @scale @sendilkumarn

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Recap • Microservices • Kubernetes • Reactive splitting your services enable you to scale faster super power to manage & maintain your services @scale makes things fast & resilient @sendilkumarn

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Recap • Microservices • Kubernetes • Reactive • KHipster splitting your services enable you to scale faster super power to manage & maintain your services @scale makes things fast & resilient makes it easier to develop & deploy @sendilkumarn

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Recap • Microservices • Kubernetes • Reactive • KHipster • Demo splitting your services enable you to scale faster super power to manage & maintain your services @scale makes things fast & resilient makes it easier to develop & deploy @sendilkumarn

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Thanks Questions/Thoughts - feel free to reach out. @sendilkumarn