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Multi-architecture fleets

Pure Java bytecode is architecture-neutral, so the same Brewlet artifact can run on provisioned amd64 and arm64 nodes. Brewlet installs a JDK root for each node's architecture and publishes its operator, provisioner, admission, and shim components for both architectures.

Portable JARs

For a JAR without native libraries, omit the architecture constraint. Kubernetes can schedule the workload on any ready node that offers the requested JDK and launcher:

apiVersion: brewlet.sh/v1alpha1
kind: JavaApplication
metadata:
  name: orders
spec:
  artifact:
    image: registry.example.com/team/orders:1.4.2
  jvm:
    version: 21

The provisioner selects the matching JDK image platform for each node. No architecture-specific application build is required.

JARs with native libraries

A JAR that bundles JNI libraries or architecture-specific dependencies is not portable. Set spec.arch on a JavaApplication, or arch in the launch config:

spec:
  arch: [amd64]

{
  "schemaVersion": 1,
  "mainJar": "app.jar",
  "entry": { "mode": "jar" },
  "arch": ["amd64"]
}

The admission webhook converts this constraint into required node affinity using the standard kubernetes.io/arch label. If the cluster has no compatible ready node, admission reports NoCompatibleArch.

The CLI and Maven plugin scan JARs for bundled .so, .dll, and .dylib files and can infer the corresponding architecture constraint. Confirm the detected value when a dependency packages native code under a nonstandard layout.

AppCDS archives

AppCDS archives are tied to both the exact JDK build and the CPU architecture. Prefer node-side regeneration to preserve one-artifact-anywhere portability. If you ship a prebuilt archive, set the artifact's architecture constraint and rely on -Xshare:auto for safe fallback when the archive does not match.

Operating a mixed fleet

  • Keep the same requested JDK features available on every architecture you intend to serve.
  • Use multi-platform component image references so each node pulls the matching operator, provisioner, admission, and shim image.
  • Inspect node inventory with brewlet jdks and Kubernetes labels before rolling out an architecture-constrained application.
  • See JDK management and observability for operational commands.