fixup: Ensure bootstrap tester image build is multiplatform

This supports building an image on a mac that will work in an amd64
eks cluster.

scripts/build_bootstrap_tester_image.sh

@@ -18,10 +18,20 @@ fi
 # Build the avalanchego image
 DOCKER_CMD="docker buildx build"
 
+# TODO(marun) Figure out how best to support this in CI and locally
+PLATFORMS="${PLATFORMS:-}"
+
+# Build the avalanchego image local-only
+PLATFORMS="${PLATFORMS}" IMAGE_PREFIX= ./scripts/build_image.sh
+AVALANCHEGO_NODE_IMAGE="avalanchego:${IMAGE_TAG}"
+
 # Specifying an image prefix will ensure the image is pushed after build
 IMAGE_PREFIX="${IMAGE_PREFIX:-}"
 if [[ -n "${IMAGE_PREFIX}" ]]; then
   IMAGE_NAME="${IMAGE_PREFIX}/${IMAGE_NAME}"
+  if [[ -n "${PLATFORMS}" ]]; then
+    DOCKER_CMD="${DOCKER_CMD} --platform=${PLATFORMS}"
+  fi
   DOCKER_CMD="${DOCKER_CMD} --push"
 
   # Tag the image as latest for the master branch
@@ -33,19 +43,14 @@ if [[ -n "${IMAGE_PREFIX}" ]]; then
   if [[ -n "${DOCKER_USERNAME:-}" ]]; then
     echo "$DOCKER_PASS" | docker login --username "$DOCKER_USERNAME" --password-stdin
   fi
-
-  # The avalanchego image will have already have been built
-  AVALANCHEGO_NODE_IMAGE="${IMAGE_PREFIX}/avalanchego:${IMAGE_TAG}"
-else
-  # Build the avalanchego image locally
-  ./scripts/build_image.sh
-  AVALANCHEGO_NODE_IMAGE="avalanchego:${IMAGE_TAG}"
 fi
 
 # The dockerfiles don't specify the golang version to minimize the changes required to bump
 # the version. Instead, the golang version is provided as an argument.
 GO_VERSION="$(go list -m -f '{{.GoVersion}}')"
 
+PLATFORMS="${PLATFORMS:-linux/amd64,linux/arm64}"
+
 # Build the image for the bootstrap tester
 ${DOCKER_CMD} -t "${IMAGE_NAME}:${IMAGE_TAG}" \
               --build-arg GO_VERSION="${GO_VERSION}" --build-arg AVALANCHEGO_NODE_IMAGE="${AVALANCHEGO_NODE_IMAGE}" \

scripts/build_image.sh

@@ -71,6 +71,11 @@ if [[ "${DOCKER_IMAGE}" == *"/"* ]]; then
     echo "$DOCKER_PASS" | docker login --username "$DOCKER_USERNAME" --password-stdin
   fi
 else
+  PLATFORMS="${PLATFORMS:-}"
+  if [[ -n "${PLATFORMS}" ]]; then
+    DOCKER_CMD="${DOCKER_CMD} --platform=${PLATFORMS}"
+  fi
+
   # Build a single-arch image since the image name does not include a slash which
   # indicates that a registry is not available.
   #

tests/bootstrap/Dockerfile

@@ -5,10 +5,30 @@ ARG GO_VERSION
 # AVALANCHEGO_NODE_IMAGE needs to identify an existing node image and should include the tag
 ARG AVALANCHEGO_NODE_IMAGE
 
-FROM golang:$GO_VERSION-bullseye AS builder
+# ============= Compilation Stage ================
+# Always use the native platform to ensure fast builds
+FROM --platform=$BUILDPLATFORM golang:$GO_VERSION-bullseye AS builder
 
 WORKDIR /builder_workdir
 
+ARG TARGETPLATFORM
+ARG BUILDPLATFORM
+
+# Configure a cross-compiler if the target platform differs from the build platform.
+#
+# build_env.sh is used to capture the environmental changes required by the build step since RUN
+# environment state is not otherwise persistent.
+# TODO(marun) Extract a common multi-platform builder from this and the avalanchego Dockerfile.
+RUN if [ "$TARGETPLATFORM" = "linux/arm64" ] && [ "$BUILDPLATFORM" != "linux/arm64" ]; then \
+    apt-get update && apt-get install -y gcc-aarch64-linux-gnu && \
+    echo "export CC=aarch64-linux-gnu-gcc" > ./build_env.sh \
+    ; elif [ "$TARGETPLATFORM" = "linux/amd64" ] && [ "$BUILDPLATFORM" != "linux/amd64" ]; then \
+    apt-get update && apt-get install -y gcc-x86-64-linux-gnu && \
+    echo "export CC=x86_64-linux-gnu-gcc" > ./build_env.sh \
+    ; else \
+    echo "export CC=gcc" > ./build_env.sh \
+    ; fi
+
 # Copy and download avalanche dependencies using go mod
 COPY go.mod .
 COPY go.sum .
@@ -21,7 +41,10 @@ COPY . .
 RUN [ -d ./build ] && rm -rf ./build/* || true
 
 # Build tester binary
-RUN ./scripts/build_bootstrap_tester.sh
+RUN . ./build_env.sh && \
+    echo "{CC=$CC, TARGETPLATFORM=$TARGETPLATFORM, BUILDPLATFORM=$BUILDPLATFORM}" && \
+    export GOARCH=$(echo ${TARGETPLATFORM} | cut -d / -f2) && \
+    ./scripts/build_bootstrap_tester.sh
 
 # ============= Cleanup Stage ================
 FROM $AVALANCHEGO_NODE_IMAGE AS execution