fix(ci): specify target machine architecture for binary build

Signed-off-by: Raphanus Lo <yunchang.lo@suse.com>

Dockerfile.dapper

@@ -6,7 +6,7 @@ ARG https_proxy
 
 ENV HOST_ARCH=${DAPPER_HOST_ARCH} ARCH=${DAPPER_HOST_ARCH}
 ENV DAPPER_DOCKER_SOCKET true
-ENV DAPPER_ENV TAG REPO DRONE_REPO DRONE_PULL_REQUEST DRONE_COMMIT_REF
+ENV DAPPER_ENV TAG REPO DRONE_REPO DRONE_PULL_REQUEST DRONE_COMMIT_REF ARCHS
 ENV DAPPER_OUTPUT bin coverage.out
 ENV DAPPER_SOURCE /go/src/github.com/longhorn/backing-image-manager
 
@@ -31,4 +31,4 @@ RUN curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/i
 ## Install Docker Buildx: The docker version in dapper is too old to have buildx. Install it manually.
 RUN curl -sSfLO https://github.com/docker/buildx/releases/download/v0.13.1/buildx-v0.13.1.linux-${ARCH} && \
     chmod +x buildx-v0.13.1.linux-${ARCH} && \
-    mv buildx-v0.13.1.linux-${ARCH} /usr/local/bin/buildx
+    mv buildx-v0.13.1.linux-${ARCH} /usr/local/bin/buildx

scripts/build

@@ -20,7 +20,22 @@ cd $(dirname $0)/..
 
 mkdir -p bin
 
-archs=("amd64" "arm64")
-for arch in "${archs[@]}"; do
-    CGO_ENABLED=0 GOARCH="$arch" go build -o "bin/backing-image-manager-$arch" -ldflags "$LINKFLAGS $OTHER_LINKFLAGS" $COVER $COVERPKG
+ARCHS=${ARCHS:-''}
+if [[ -z "${ARCHS}" ]]; then
+    case $(uname -m) in
+    aarch64 | arm64)
+        ARCHS=(arm64)
+        ;;
+    x86_64)
+        ARCHS=(amd64)
+        ;;
+    *)
+        echo "$(uname -a): unsupported architecture"
+        exit 1
+    esac
+else
+    IFS=' ' read -r -a ARCHS <<<"${ARCHS}"
+fi
+for arch in "${ARCHS[@]}"; do
+    CGO_ENABLED=0 GOARCH="${arch}" go build -o "bin/backing-image-manager-${arch}" -ldflags "${LINKFLAGS} ${OTHER_LINKFLAGS}" ${COVER} ${COVERPKG}
 done