Build developers local platform by default

Signed-off-by: Austin Vazquez <austin.vazquez@docker.com>

Author: austinvazquez

.github/workflows/ci.yml

@@ -157,20 +157,21 @@ jobs:
         os: [ubuntu-latest, ubuntu-24.04-arm]
 
     env:
-      KERNEL_ARCH: ""
+      # Set in step by runner.
+      ARCH: ""
 
     steps:
       - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8  # v6.0.1
 
       - name: Set env
         run: |
-          echo "KERNEL_ARCH=$(uname -m)" >> $GITHUB_ENV
+          echo "ARCH=$(uname -m)" >> $GITHUB_ENV
 
       - name: Calculate kernel cache key
         id: cache-key
         run: |
           # Hash the kernel config and patches to create a unique cache key
-          CONFIG_FILE="kernel/config-${{ needs.setup.outputs.kernel-version }}-${KERNEL_ARCH}"
+          CONFIG_FILE="kernel/config-${{ needs.setup.outputs.kernel-version }}-${{ env.ARCH }}"
 
           if [ ! -f "$CONFIG_FILE" ]; then
             echo "Error: Kernel config file $CONFIG_FILE not found"
@@ -182,7 +183,7 @@ jobs:
           PATCHES_HASH=$(find kernel/patches -type f -name "*.patch" -exec sha256sum {} \; | sort | sha256sum | cut -d' ' -f1)
 
           # Combine version, arch, config hash, and patches hash
-          CACHE_KEY="kernel-${{ needs.setup.outputs.kernel-version }}-${KERNEL_ARCH}-${CONFIG_HASH:0:8}-${PATCHES_HASH:0:8}"
+          CACHE_KEY="kernel-${{ needs.setup.outputs.kernel-version }}-${{ env.ARCH }}-${CONFIG_HASH:0:8}-${PATCHES_HASH:0:8}"
 
           echo "cache-key=${CACHE_KEY}" >> $GITHUB_OUTPUT
           echo "Kernel cache key: ${CACHE_KEY}"
@@ -191,7 +192,7 @@ jobs:
         id: cache-kernel
         uses: actions/cache/restore@1bd1e32a3bdc45362d1e726936510720a7c30a57  # v4.2.0
         with:
-          path: _output/nerdbox-kernel-${{ env.KERNEL_ARCH }}
+          path: _output/nerdbox-kernel-${{ env.ARCH }}
           key: ${{ steps.cache-key.outputs.cache-key }}
 
       - name: Verify kernel from cache
@@ -202,23 +203,23 @@ jobs:
             echo "❌ Kernel not in cache - this should not happen after build-kernels-on-demand"
             exit 1
           fi
-          ls -lh _output/nerdbox-kernel-${KERNEL_ARCH}
-          file _output/nerdbox-kernel-${KERNEL_ARCH}
+          ls -lh _output/nerdbox-kernel-${{ env.ARCH }}
+          file _output/nerdbox-kernel-${{ env.ARCH }}
 
       - uses: docker/setup-buildx-action@e468171a9de216ec08956ac3ada2f0791b6bd435  # v3.11.1
 
       - name: Build remaining artifacts (initrd and shim)
         run: |
-          echo "Building shim, initrd and libkrun..."
-          docker buildx bake shim initrd libkrun
+          echo "Building host and guest binaries:"
+          docker buildx bake host-binaries guest-binaries
 
       - name: Verify all artifacts
         run: |
           echo "Verifying build artifacts:"
           ls -lh _output/
           echo ""
           echo "Kernel:"
-          file _output/nerdbox-kernel-${KERNEL_ARCH}
+          file _output/nerdbox-kernel-${{ env.ARCH }}
           echo ""
           echo "Initrd:"
           file _output/nerdbox-initrd

Dockerfile

@@ -97,10 +97,9 @@ ARG GO_BUILD_FLAGS
 ARG GO_LDFLAGS
 ARG TARGETOS
 ARG TARGETARCH
-ARG TARGETPLATFORM
 
 RUN --mount=type=bind,target=.,rw \
-    --mount=type=cache,target=/root/.cache/go-build,id=shim-build-$TARGETPLATFORM \
+    --mount=type=cache,target=/root/.cache/go-build,id=shim-build-${TARGETOS}/${TARGETARCH} \
     GOOS=${TARGETOS} GOARCH=${TARGETARCH} go build ${GO_DEBUG_GCFLAGS} ${GO_GCFLAGS} ${GO_BUILD_FLAGS} -o /build/containerd-shim-nerdbox-v1 ${GO_LDFLAGS} -tags 'no_grpc' ./cmd/containerd-shim-nerdbox-v1
 
 FROM base AS vminit-build

Makefile

@@ -21,8 +21,11 @@ ROOTDIR=$(patsubst %/,%,$(dir $(abspath $(lastword $(MAKEFILE_LIST)))))
 WHALE = "🇩"
 ONI = "👹"
 
-ARCH = $(shell uname -m)
-OS = $(shell uname -s)
+# Detect local platform; 'linux' or 'darwin'
+OS ?= $(shell uname -s | tr '[:upper:]' '[:lower:]')
+ARCH ?= $(shell uname -m)
+export PLATFORM ?= $(OS)/$(ARCH)
+
 LDFLAGS_x86_64_Linux = -lkrun
 LDFLAGS_aarch64_Linux = -lkrun
 LDFLAGS_arm64_Darwin = -L/opt/homebrew/lib -lkrun
@@ -52,10 +55,13 @@ GO_STATIC_LDFLAGS := -ldflags '-extldflags "-static" $(LDFLAGS) $(EXTRA_LDFLAGS)
 MODULE_NAME=$(shell go list -m)
 API_PACKAGES=$(shell ($(GO) list ${GO_TAGS} ./... | grep /api/ ))
 
-.PHONY: clean all validate lint generate protos check-protos check-api-descriptors proto-fmt shell
+.PHONY: clean all build validate lint generate protos check-protos check-api-descriptors proto-fmt shell
+
+all: build
 
-all:
-	$(BUILDX) bake
+build:
+	@echo "$(WHALE) $@"
+	HOST_OS=$(OS) ARCH=$(ARCH) $(BUILDX) bake
 
 _output/containerd-shim-nerdbox-v1: cmd/containerd-shim-nerdbox-v1 FORCE
 	@echo "$(WHALE) $@"

docker-bake.hcl

@@ -1,9 +1,14 @@
-variable "KERNEL_VERSION" {
-  default = "6.12.46"
+# The host and guest OS may differ; set the host OS here.
+variable "HOST_OS" {
+  default = "linux"
+}
+
+variable "ARCH" {
+  default = "amd64"
 }
 
-variable "KERNEL_ARCH" {
-  default = "x86_64"
+variable "KERNEL_VERSION" {
+  default = "6.12.46"
 }
 
 variable "KERNEL_NPROC" {
@@ -30,10 +35,16 @@ variable "GOLANGCI_LINT_MULTIPLATFORM" {
   default = ""
 }
 
+function "kernelArch" {
+  params = []
+  result = ARCH == "amd64" ? "x86_64" : (ARCH == "arm64" ? "arm64" : "unknown")
+}
+
 target "_common" {
   args = {
+    TARGETARCH = ARCH
     KERNEL_VERSION = KERNEL_VERSION
-    KERNEL_ARCH = KERNEL_ARCH
+    KERNEL_ARCH = kernelArch()
     KERNEL_NPROC = KERNEL_NPROC
     GO_BUILD_FLAGS = GO_BUILD_FLAGS
     GO_GCFLAGS = GO_GCFLAGS
@@ -42,44 +53,66 @@ target "_common" {
   }
 }
 
+target "_host_common" {
+  inherits = ["_common"]
+  args = {
+    TARGETOS = HOST_OS
+  }
+}
+
+target "_guest_common" {
+  inherits = ["_common"]
+  args = {
+    TARGETOS = "linux"
+  }
+}
+
 variable "DESTDIR" {
   default = "_output"
 }
 
+group "default" {
+  targets = ["host-binaries", "guest-binaries", "kernel"]
+}
+
+group "host-binaries" {
+  targets = ["shim"]
+}
+
+group "guest-binaries" {
+  targets = ["initrd", "libkrun"]
+}
+
 target "menuconfig" {
   inherits = ["_common"]
   target = "kernel-build-base"
   output = ["type=image,name=nerdbox-menuconfig"]
 }
 
 target "kernel" {
-  inherits = ["_common"]
+  inherits = ["_guest_common"]
   target = "kernel"
   output = ["${DESTDIR}"]
 }
 
 target "initrd" {
-  inherits = ["_common"]
+  inherits = ["_guest_common"]
   target = "initrd"
   output = ["${DESTDIR}"]
 }
 
 target "shim" {
-  inherits = ["_common"]
+  inherits = ["_host_common"]
   target = "shim"
   output = ["${DESTDIR}"]
 }
 
 target "libkrun" {
-  inherits = ["_common"]
+  inherits = ["_guest_common"]
   target = "libkrun"
   output = ["${DESTDIR}"]
 }
 
-group "default" {
-    targets = ["kernel", "initrd", "shim"]
-}
-
 target "dev" {
   inherits = ["_common"]
   target = "dev"