Best Practices to Spring (or Java) to Kubernetes Faster and Easier

For Spring developers, building containers is a common obstacle on the road to Kubernetes adoption. Traditionally, Dockerfiles define container builds imperatively, but can also be cumbersome, error-prone, and slow. The development cycle can be slow. IDE support is generally poor. Most likely, your Java application will crash with an OOMKill message.

In this talk, we'll introduce tools and best practices to help you adopt Kubernetes faster and easier. This includes tools such as Jib and Skaffold for fast image build and development cycle turnaround time. We'll also discuss best practices for configuring your Java applications to run inside of Kubernetes, such as health checks, zero downtime deployment, externalizing configurations, logging, and understanding memory usage to avoid OOMKilled situations.

Talk at CodeOne and SpringOne. Recording from SpringOne: https://www.youtube.com/watch?v=YTPUNesUIbI&list=PL4uYfigiauVYH4OwOyq8FGbPQOn-JueEf&index=3&t=0s

Transcript

1. Kubernetes Faster and Easier
   

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2. 2
   @saturnism @gcpcloud
   Ray Tsang
   Developer Advocate
   Google Cloud Platform
   Java Champion
   Spring Cloud GCP
   spring.io/projects/spring-cloud-gcp
   gcplab.me/spring
   @saturnism | saturnism.me
   

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3. 3
   @saturnism @gcpcloud
   Ray Tsang
   Traveler
   Photographer
   flickr.com/saturnism
   

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4. 4
   @saturnism @gcpcloud
   https://www.youtube.com/watch?v=Bcs-inRnLDc
   

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5. 5
   @saturnism @gcpcloud 5
   Your App
   

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   @saturnism @gcpcloud
   Don't start with Kubernetes
   

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   @saturnism @gcpcloud
   It all starts with your application
   Twelve-Factor App
   12factor.net
   

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8. 8
   @saturnism @gcpcloud
   Test, Test, Test
   Local
   Mock, Wiremock, Contract
   TestContainers
   

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9. 9
   @saturnism @gcpcloud 9
   Containers
   

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    @saturnism @gcpcloud
    Power → Responsibility
    Runtime Environments may be Your Responsibility Now!
    

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    @saturnism @gcpcloud
    Choose a JDK
    Container Aware
    OpenJDK 8u192 or above
    

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    @saturnism @gcpcloud
    OOMKilled
    Cloud Foundry Buildpack Memory Calculator
    https://github.com/cloudfoundry/java-buildpack-memory-calculator
    

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    @saturnism @gcpcloud
    Native Memory Tracking
    -XX:NativeMemoryTracking=summary -XX:+PrintNMTStatistics
    (Doesn't work when set via JAVA_TOOL_OPTIONS - must be part of the argument)
    

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    @saturnism @gcpcloud
    Container Best Practices
    saturnism.me/talk/docker-tips-and-tricks/
    What's in that image?
    Don't run as root
    Multi-stage build
    Create small image
    Fat JAR to Thin JAR
    Layering
    Build cache
    Pin versions
    Reduce layer size
    ...
    

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    @saturnism @gcpcloud
    Just Jib It
    

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    @saturnism @gcpcloud
    Don't write to container filesystem!
    Those logs!
    

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    @saturnism @gcpcloud
    Configuration via external sources
    Environmental variable
    Command line arguments
    

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    @saturnism @gcpcloud 18
    Finally, Kubernetes!
    

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    @saturnism @gcpcloud
    Local Kubernetes
    Linux - consider k3s, k3d, kind, …
    Mac - Docker for Desktop, Minikube
    

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    @saturnism @gcpcloud
    Keep Base Deployment Simple
    kubectl create deployment myservice --image=... --dry-run -oyaml > k8s/deployment.yaml
    kubectl create svc clusterip myservice --tcp=8080:8080 --dry-run -oyaml/service.yaml
    

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21. 21
    @saturnism @gcpcloud
    Continuous Development
    skaffold
    

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    @saturnism @gcpcloud
    Resource Limits
    If you don't' set it, your app may use all the memory...
    Set it at namespace level, or for individual deployments
    

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    @saturnism @gcpcloud
    Environments
    Kustomize
    

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    @saturnism @gcpcloud
    Liveness Probe
    Readiness Probe
    Signals
    Lifecycle Hooks
    

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    @saturnism @gcpcloud
    Liveness Probe → Restarts
    Readiness Probe → Remove from Service
    Signals → Shutdown or Killed
    Lifecycle Hooks → PreStart, PreStop
    

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    @saturnism @gcpcloud
    When to use? Failure Means... Practices Example
    Liveness
    Probe
    If application is
    alive.
    Application will be
    restarted, and that a
    restart will help recover.
    Runs on serving port of the
    application, e.g., 8080.
    Don't check dependency. E.g.,
    don't check dependent database
    connection, etc.
    A simple /alive URL
    that returns 200.
    Readiness
    Probe
    Ready to serve
    requests.
    Take the pod instance
    out of load balancer.
    Flip to ready when application has
    done all the initializations (cache
    preloaded).
    Upon SIGTERM, flip readiness to
    false. See Graceful Shutdown.
    /actuator/health on
    the management
    port.
    

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    @saturnism @gcpcloud
    Anatomy of a Graceful Shutdown
    1. Receive SIGTERM or PreStop Lifecycle Hook
    2. Fail Readiness Probe
    3. Receive requests until Kubernetes detects readiness probe
    failure
    4. Kubernetes removes pod endpoint from Service
    5. Finish serving in-flight requests
    6. Shutdown
    

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    @saturnism @gcpcloud
    Production is HARD
    Pod Security Policy / Pod Security Context
    Expect your app to not work in production environment with hardened security
    Try this early and fix issues
    

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    @saturnism @gcpcloud 29
    Thanks!
    spring.io/projects/spring-cloud-gcp
    cloud.google.com/java
    Come to the Google Cloud Platform Booth!
    @saturnism | saturnism.me
    

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