Cross-Compilation Guide

Kepler Operator supports building for multiple architectures (amd64, arm64). Since the operator uses CGO_ENABLED=0, Go handles cross-compilation natively — no C cross-compiler or sysroot is needed.

Building ARM64 Binaries

# Cross-compile binary for ARM64
make build-manager GOARCH=arm64

Building Container Images

Single-arch

# Build an ARM64 container image (loads into local Docker)
make operator-build GOARCH=arm64

# Build an amd64 container image (default)
make operator-build

Multi-arch

Multi-arch builds use per-arch docker build followed by docker manifest to create a manifest list. Images are built locally, then pushed and assembled into a manifest in a separate step.

# Build multi-arch operator images locally (amd64 + arm64)
make operator-build-multi

# Push images and create multi-arch manifest
make operator-push-multi

# Same for bundle images
make bundle-build-multi
make bundle-push-multi

# Customize architectures
make operator-build-multi IMAGE_ARCHES="amd64 arm64 ppc64le"

Full multi-arch build and deploy workflow

# Build multi-arch operator + generate bundle + build multi-arch bundle
make operator-build-multi bundle bundle-build-multi \
  IMG_BASE=quay.io/your-registry \
  VERSION=0.0.0-dev \
  KEPLER_IMG=quay.io/your-registry/kepler:latest

# Push all images and create manifests
make operator-push-multi bundle-push-multi \
  IMG_BASE=quay.io/your-registry \
  VERSION=0.0.0-dev

# Deploy via OLM
operator-sdk run bundle quay.io/your-registry/kepler-operator-bundle:0.0.0-dev \
  --install-mode AllNamespaces \
  --namespace operators

How it works

The Dockerfile uses FROM --platform=$BUILDPLATFORM on the builder stage so the Go compiler always runs natively on the host architecture. Cross-compilation is achieved by passing GOARCH=$TARGETARCH to go build. This avoids QEMU emulation entirely, making builds fast and reliable.

The oc CLI (needed for must-gather) is downloaded from the official OpenShift mirror for the target architecture rather than pulled from a container image, ensuring ARM64 support.

Makefile Variables

Variable	Default	Description
GOARCH	host arch	Target architecture for single-arch builds
IMAGE_ARCHES	amd64 arm64	Architectures built by *-multi targets