Add GraalVM native image support for Fabric8 autoconfig module

[kamalcis]

Problem

Spring Cloud Kubernetes Fabric8 autoconfig module does not support
GraalVM native image compilation. The README explicitly states native
images are unsupported. Native builds fail at runtime with:

java.lang.ClassNotFoundException:
io.fabric8.kubernetes.client.impl.KubernetesClientImpl

Closes #1350

Testing Environment

Tested on:

• GraalVM CE 25.0.2
• Spring Boot 4.1.0-SNAPSHOT
• Spring Cloud Kubernetes 5.0.2-SNAPSHOT
• Kubernetes 1.34.1 (live kubeadm cluster)

Reproduce

• Cloned the sck library from https://github.com/spring-cloud/spring-cloud-kubernetes
• Installed the sck library to local repo.
  cd spring-cloud-kubernetes> ./mvnw clean install -DskipTests -Dspring-boot.build-image.skip=true
• The link of app repo I used to test: https://github.com/kamalcis/graalvm-sck-app
• Build the app. cd graalvm-sck-app> ./mvnw -Pnative native:compile -DskipTests
• Now the Aot Binary is ready in the target folder. (Build outside because container does not refer local repo)
• Used Podman to build the docker image. ( Docker just copied the aot binary file into working directory)
• Deploy the Kubernetes Objects ( Deployment, Service, Secret, Configmap, Service Account, Role, Rolebinding) using
  https://github.com/kamalcis/graalvm-sck-app/blob/main/k8s.yaml ( kubectl apply -f k8s.yaml)
• Once Kubernetes is up and running set the image to deployment that has been built by podman, make sure rollout restart .
• This is important to keep the same name for the app, configmap, secret name e.g. (In this case graalvm-sck-app)
• Expect to see no error if PR is merged. Before merge ClassNotFoundException should be thrown in kubernetes

Solution

Add Fabric8RuntimeHints implementing RuntimeHintsRegistrar to register:

• Reflection hints for KubernetesClientImpl, KubernetesClientBuilder,
  and Config
• Reflection hint for Fabric8ProfileEnvironmentPostProcessor
• Resource hints for Kubernetes service account and kubeconfig files

Note

User applications must set spring.main.cloud-platform=kubernetes
in their configuration to enable SCK auto-configuration in
native image environments. Auto-detection of the Kubernetes
platform is not yet supported in native images and is a
separate concern from this PR.

Results on Merge:
Deployed the user application image ( containing the SCK library ) into Kubeadm cluster. Pods started successfully, logs were clean, and SCK auto-configuration loaded correctly at runtime. Pods start instantly, logs are clean, and SCK auto-configuration loads correctly at runtime.

[kamalcis]

Validated end-to-end on a live kubeadm cluster (Kubernetes 1.34.1, GraalVM CE 25.0.2, Spring Cloud Kubernetes 5.0.2-SNAPSHOT, Spring Boot 4.1.0-SNAPSHOT). Called the REST endpoint from within the cluster and received the expected response — both ConfigMap and Secret values were successfully injected into the application via Spring Cloud Kubernetes at native image runtime, as demonstrated in the screenshot above.

[kamalcis]

Hi @ryanjbaxter, I hope you're well!
I have completed the end-to-end validation of this PR. Now ConfigMap, Secret, and environment variable injection are all working correctly in the native image as shown in the attached screenshots.
Would you be able to take a look at the implementation when you get a chance? I would love to get your feedback and am keen to collaborate further on this. Happy to make any adjustments you suggest.
Thank you for your time!

[ryanjbaxter]

Thanks! I think this would be a good feature for our 2026 release which will be sometime towards the end of the year

[kamalcis]

Thanks! I think this would be a good feature for our 2026 release which will be sometime towards the end of the year

Thank you so much for triaging this and adding it to the 2026.0.0-M1 milestone. Please let me know if there's anything you'd like me to address. Looking forward to collaborating on this!