Knative and Spring: Bringing back the func

Kubernetes is now a standard to deploy and manage containerized applications. How do functions fit into the cloud-native space in 2022? What does it take to write a function in Java or any other language and get it up and running in a Kubernetes cluster?

We’ll show with practical examples and a live demo how developers can focus on the business logic while the platform takes care of supporting event-driven and serverless workloads in a polyglot environment.

- CloudEvents provide a language and transport-agnostic way to describe events.
- Knative Eventing routes CloudEvents between producers and consumers so that developers don’t have to worry about which message broker is used under the hood (e.g. RabbitMQ, Kafka, cloud-provider specific).
- Frameworks like Spring Cloud Functions let developers focus on implementing the business logic instead of dealing with infrastructural concerns and integrations with event brokers.
- GraalVM and libraries like Spring Native make it possible to build serverless applications in Java and take advantage of the scale-to-zero feature offered by Knative Serving.
- Cloud-Native Buildpacks solve the problem of building production-ready containers end to end, offering support for multiple languages and frameworks, and focusing on performance and security.

To demonstrate how all these tools can work together, we will show how Knative func combines them and provide developers with a Dockerfile-free and Kubernetes YAML-free experience.

Transcript

1. Mauricio Salatino & Thomas Vitale Spring I/O May 27th, 2022 Knative and Spring Bringing back the func @salaboy @vitalethomas
2. Mauricio Salatino VMware - Knative OSS • a.k.a @Salaboy • Sta ff Engineer - Knative Eventing tech lead for VMware • Knative OSS core contributor • Passionate about Functions, Platforms, Open Source and Kubernetes salaboy.com
3. Systematic • Software Architect at Systematic, Denmark. • Author of “Cloud Native Spring in Action” (Manning). • Spring Security and Spring Cloud contributor. Thomas Vitale thomasvitale.com @vitalethomas
4. Quiz Game thomasvitale.com @vitalethomas @salaboy @vitalethomas Building applications using functions
5. Serverless @salaboy @vitalethomas
6. Serverless Architectures Developers focus on code Focus on business logic @salaboy @vitalethomas Developer Platform Infrastructure Provisioning Workload Management Dynamic Scaling
7. Knative Serving Serverless Containers on Kubernetes Developer-friendly abstractions From code to URL Autoscaling Scaling to zero Progressive Rollouts Request-driven Event-driven @salaboy @vitalethomas Cloud agnostic
8. buildpacks.io
9. Demo thomasvitale.com @vitalethomas @salaboy @vitalethomas Knative Serving and Buildpacks - From code to URL
10. Platform v1 - Serverless experience From containers to deployment with autoscaling @salaboy @vitalethomas Image pack kn URL Kubernetes Cluster Container Container Container Knative Serving
11. Functions @salaboy @vitalethomas
12. Demo thomasvitale.com @vitalethomas @salaboy @vitalethomas Knative Functions - From code to URL
13. Functions Functional programming model Triggered by requests or events Stateless Smaller scope Cold start Cost optimization @salaboy @vitalethomas
14. Functions Patterns Topologies for functional programming @salaboy @vitalethomas Asynchronous processing Event-based Data stream via chained functions Synchronous Asynchronous Fire and Forget Request/ Response Request/ Response (State)
15. Knative Functions Working with the func CLI @salaboy @vitalethomas func create ‣Initialize project ‣Polyglot support ‣Java, Go, Python 1 func build ‣Build and containerize ‣Use Buildpacks ‣No Docker fi le 2 func deploy ‣Run on Kubernetes ‣Knative deployment ‣No YAML 3
16. More on Knative Functions In active development, join the community! External templates repository Run locally with func run On-cluster build, no Docker required Roadmap to 1.0 GA @salaboy @vitalethomas Works with multiple languages and frameworks
17. Platform v2 - Polyglot Functions From idea to deployment with autoscaling @salaboy @vitalethomas URL func create Image func deploy Kubernetes Cluster Container Container Container Knative Serving
18. Functions with Spring @salaboy @vitalethomas
19. Spring Native Native executables with GraalVM Slower Heavier Build Instant Startup Reduced Memory Consumption Instant Peak Performance Fewer Runtime Optimizations @salaboy @vitalethomas
20. Functional Programming Paradigm Java 8 Functional Interfaces Supplier<O> Function<I,O> Consumer<I> @salaboy @vitalethomas
21. Spring Cloud Function Business logic as functions Transparent Type Conversion Function Arity Function Composition Reactive Support JAR Functions @salaboy @vitalethomas
22. Demo thomasvitale.com @vitalethomas @salaboy @vitalethomas Knative Functions - From code to URL
23. Function Composition Data processing via functions uppercase() sentence() Data processing “I play the PIANO” “piano” “PIANO”
24. Spring Cloud Function Deployment and integrations Knative CloudEvents RSocket Azure Functions Google Cloud Functions AWS Lambda @salaboy @vitalethomas
25. Events @salaboy @vitalethomas
26. CloudEvents Interoperability and standardization Metadata Data Id Source Type Payload JSON AMQP Kafka MQTT @salaboy @vitalethomas
27. Spring Cloud Functions Routing Routing Events to functions A() CloudEvent B() C() Router [Ce-Type]
28. Knative Eventing Event routing and triggers Developer-friendly abstractions Event-driven architectures Event routing Polyglot support with CloudEvents Pluggable @salaboy @vitalethomas Cloud agnostic
29. Platform v3 - Knative Eventing Event-driven and reactive functions @salaboy @vitalethomas URL func create + trigger Image func deploy Kubernetes Cluster Container Container Knative Serving & Eventing Knative Broker Knative Event Sources Trigger A Trigger B
30. Game - Architecture @salaboy @vitalethomas
31. Kubernetes Cluster Game - Functions Synchronous functions with Knative <Client Side> React Application <Orchestrator> Game FrontEnd <Function> Start Game <Function> Level X … <Function> Get LeaderB Redis (State) HTTP SYNC <Function> Level 1 …
32. Takeaways and challenges Synchronous functions Functions scale up and down based on demand An Orchestrator is needed Synchronising state is hard Make sure that the data store is not a bottleneck Latency can become an issue @salaboy @vitalethomas
33. Game - Eventing Knative Eventing, CloudEvents & RSocket Kubernetes Cluster <Client Side> React Application <Orchestrator> Game FrontEnd <Function> Level X … Redis HTTP SYNC Broker Trigger Score CloudEvent RSocket GameScore CloudEvent Trigger Another Function
34. Takeaways and challenges Eventing An event-based approach enable more reactive scenarios Knative Eventing abstracts the message broker implementations CloudEvents provide a standard structure for sharing data Monitoring is required to understand how data is fl owing We need to deal with eventual consistency in our applications @salaboy @vitalethomas
35. Discount codes Manning • 45% discount code, valid for all products in all format • ctwspringio22 • manning.com
36. Resources Source code • Learn more about the game: • https://github.com/salaboy/from-monolith-to-k8s/tree/main/game • Deploy the game on Kubernetes: • https://github.com/ThomasVitale/eventing-game • Spring Cloud Function samples: • https://github.com/ThomasVitale/springio-2022-knative-spring-func