Mauricio Salatino and Thomas Vitale presented on using Knative and Spring to build serverless applications with functions. They demonstrated how to deploy functions from code to a URL using Knative Serving and Functions. They also discussed using Knative Eventing to build event-driven architectures and route events between functions. Finally, they proposed a game architecture using functions and events on Kubernetes and discussed challenges around scaling, latency, and consistency.

1. Mauricio Salatino & Thomas Vitale
Devoxx UK
May 11th, 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. Demo
thomasvitale.com @vitalethomas
@salaboy @vitalethomas
Knative Serving - From code to URL

9. Functions
@salaboy @vitalethomas

10. Functions
Functional programming model
Triggered by
requests or events
Stateless Smaller scope
Cold start Cost optimization
@salaboy @vitalethomas

11. Functions Patterns
Synchronous Interactions
Function
HTTP
Fire and Forget

12. Functions Patterns
Synchronous Interactions
Function
HTTP
Request / Response

13. Functions Patterns
Synchronous Interactions
Function
HTTP
Request / Response (Sync)
State

14. Functions Patterns
Synchronous Interactions
Function
HTTP
Request / Response (Scaling)
State
Function
Function
Load
Balancer

15. Functions Patterns
Synchronous Interactions
HTTP
Request / Response (Scaling)
State
Load
Balancer
Not running
useless containers

16. Functions Patterns
Asynchronous Interactions
Async Processing
Function
HTTP
Doing
something that
takes a long time
……………………………………………
…………………………………………………
……………………………………………………
………………………………………………
………………………………………
Results

17. Functions Patterns
Asynchronous Interactions
Event Based
Function
CloudEvent CloudEvent

18. Functions Patterns
Asynchronous Interactions
Chaining Functions
Function
CloudEvent
Event Router
Function Function

19. Functions Patterns
Mix and match
Function
Request / Reply + Events
CloudEvent
HTTP
Event Router

20. 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

21. Demo
thomasvitale.com @vitalethomas
@salaboy @vitalethomas
Knative Functions - From code to URL (GO)

22. Func - extras
In active development, join the community!
* External template repos
* func run
* On-cluster build, no Docker locally
* 1.0 GA is on the roadmap

23. Functions with Spring
@salaboy @vitalethomas

24. Spring Native
Native executables with GraalVM
Slower
Heavier
Build
Instant
Startup
Reduced
Memory
Consumption
Instant
Peak
Performance
Fewer
Runtime
Optimizations
@salaboy @vitalethomas

25. Functional Programming Paradigm
Java 8 Functional Interfaces
Supplier<O> Function<I,O> Consumer<I>
@salaboy @vitalethomas

26. Spring Cloud Function
Business logic as functions
Transparent
Type
Conversion
Function
Arity
Function
Composition
Reactive
Support
JAR
Functions
@salaboy @vitalethomas

27. Demo
thomasvitale.com @vitalethomas
@salaboy @vitalethomas
Knative Functions - From code to URL (Spring)

28. Function Composition
Data processing via functions
uppercase() sentence()
Data processing
“I play the PIANO”
“piano” “PIANO”

29. Spring Cloud Function
Deployment and integrations
Knative CloudEvents RSocket
Azure
Functions
Google Cloud
Functions
AWS
Lambda
@salaboy @vitalethomas

30. Game - Architecture
@salaboy @vitalethomas

31. Kubernetes Cluster
Function-based Game architecture
Game architecture
<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. Events
@salaboy @vitalethomas

34. Knative Eventing
Event routing and triggers
Developer-friendly
abstractions
Event-driven
architectures
Event routing
Polyglot support
with CloudEvents
Pluggable
@salaboy @vitalethomas
Cloud agnostic

35. CloudEvents
Interoperability and standardization
Metadata
Data
Id
Source
Type
Payload
JSON
AMQP
Kafka
MQTT

36. Game - Events
@salaboy @vitalethomas

37. Routing Events with 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

38. 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

39. Discount codes
Manning
• 35% discount code, valid for
all products in all format
• ctwdevoxxuk22
• manning.com

40. 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/devoxxuk-2022-knative-spring-func

41. Mauricio Salatino & Thomas Vitale
Devoxx UK
May 11th, 2022
Knative and Spring
Bringing back the func
@salaboy @vitalethomas