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
   

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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
   

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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
   

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4. Quiz Game
   thomasvitale.com @vitalethomas
   @salaboy @vitalethomas
   Building applications using functions
   

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5. Serverless
   @salaboy @vitalethomas
   

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6. Serverless Architectures
   Developers focus on code
   Focus on business logic
   @salaboy @vitalethomas
   Developer
   Platform
   Infrastructure
   
   Provisioning
   Workload
   
   Management
   Dynamic
   
   Scaling
   

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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
   

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8. buildpacks.io
   

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9. Demo
   thomasvitale.com @vitalethomas
   @salaboy @vitalethomas
   Knative Serving and Buildpacks - From code to URL
   

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10. Platform v1 - Serverless experience
    From containers to deployment with autoscaling
    @salaboy @vitalethomas
    Image
    pack kn
    URL
    Kubernetes Cluster
    Container
    Container
    Container
    Knative
    Serving
    

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11. Functions
    @salaboy @vitalethomas
    

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12. Demo
    thomasvitale.com @vitalethomas
    @salaboy @vitalethomas
    Knative Functions - From code to URL
    

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

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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)
    

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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
    

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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
    

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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
    

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18. Functions with Spring
    @salaboy @vitalethomas
    

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

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20. Functional Programming Paradigm
    Java 8 Functional Interfaces
    Supplier Function Consumer
    @salaboy @vitalethomas
    

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

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22. Demo
    thomasvitale.com @vitalethomas
    @salaboy @vitalethomas
    Knative Functions - From code to URL
    

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

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

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25. Events
    @salaboy @vitalethomas
    

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26. CloudEvents
    Interoperability and standardization
    Metadata
    Data
    Id
    
    Source
    
    Type
    Payload
    JSON
    
    AMQP
    
    Kafka
    
    MQTT
    @salaboy @vitalethomas
    

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27. Spring Cloud Functions Routing
    Routing Events to functions
    A()
    CloudEvent
    B()
    C()
    Router
    
    
    [Ce-Type]
    

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

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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
    

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30. Game - Architecture
    @salaboy @vitalethomas
    

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31. Kubernetes Cluster
    Game - Functions
    Synchronous functions with Knative
    
    
    
    React Application
    
    
    
    Game FrontEnd
    
    
    
    Start Game
    
    
    
    Level X
    
    
    …
    
    
    
    Get LeaderB
    Redis
    
    
    (State)
    HTTP
    SYNC
    
    
    
    Level 1
    
    
    …
    

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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
    

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33. Game - Eventing
    Knative Eventing, CloudEvents & RSocket
    Kubernetes Cluster
    
    
    
    React Application
    
    
    
    Game FrontEnd
    
    
    
    Level X
    
    
    …
    Redis
    HTTP SYNC
    Broker
    Trigger
    Score
    
    CloudEvent
    RSocket
    GameScore
    
    CloudEvent
    Trigger
    Another
    Function
    

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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
    

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35. Discount codes
    Manning
    • 45% discount code, valid for
    all products in all format
    
    • ctwspringio22
    
    
    • manning.com
    

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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
    

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