Fix the mkdir statement

Author: luxas

dnsmasq/Dockerfile.cross

@@ -13,11 +13,11 @@
 # limitations under the License.
 
 FROM BASEIMAGE
+# If we're building for another architecture than amd64, the CROSS_BUILD_ placeholder is removed so e.g. CROSS_BUILD_COPY turns into COPY
+# If we're building normally, for amd64, CROSS_BUILD lines are removed
+CROSS_BUILD_COPY qemu-ARCH-static /usr/bin/
 MAINTAINER Girish Kalele <[email protected]>
 COPY dnsmasq.conf /etc/dnsmasq.conf
 COPY dnsmasq /usr/sbin/dnsmasq
-
-# This is just a mkdir statement for /var/run in order to keep the complexity of the Makefile down
-WORKDIR /var/run
-WORKDIR /
+RUN mkdir /var/run/
 ENTRYPOINT ["/usr/sbin/dnsmasq", "--keep-in-foreground"]

dnsmasq/Makefile

@@ -30,31 +30,43 @@ TEMP_DIR:=$(shell mktemp -d)
 ifeq ($(ARCH),arm)
 	BASEIMAGE?=armel/busybox:glibc
     TRIPLE?=arm-linux-gnueabi
+    QEMUARCH=arm
 endif
 ifeq ($(ARCH),arm64)
 	BASEIMAGE?=aarch64/busybox:glibc
     TRIPLE?=aarch64-linux-gnu
+    QEMUARCH=aarch64
 endif
 ifeq ($(ARCH),ppc64le)
 	BASEIMAGE?=ppc64le/busybox:glibc
     TRIPLE?=powerpc64le-linux-gnu
+    QEMUARCH=ppc64le
 endif
 
 all: build
 
 build:
 ifeq ($(ARCH),amd64)
 	cp Dockerfile $(TEMP_DIR)
+	# When building "normally" for amd64, remove the whole line, it has no part in the amd64 image
+	cd $(TEMP_DIR) && sed -i "/CROSS_BUILD_/d" Dockerfile
 else
 	cp Dockerfile.cross $(TEMP_DIR)/Dockerfile
-	sed -i "s|BASEIMAGE|$(BASEIMAGE)|g" $(TEMP_DIR)/Dockerfile
+	cd $(TEMP_DIR) && sed -i "s|BASEIMAGE|$(BASEIMAGE)|g" Dockerfile
+	cd $(TEMP_DIR) && sed -i "s|ARCH|$(QEMUARCH)|g" Dockerfile
 
 	# Build the dnsmasq binary using the cross-compilation docker image
 	docker run -it --rm -v $(TEMP_DIR):/build $(KUBE_CROSS_IMAGE) /bin/bash -c \
 	"curl -sSL  http://www.thekelleys.org.uk/dnsmasq/$(DNSMASQ_VERSION).tar.xz | tar -xJ \
 	&& cd $(DNSMASQ_VERSION) \
 	&& CC=$(TRIPLE)-gcc make \
 	&& cp src/dnsmasq /build"
+
+	# When cross-building, only the placeholder "CROSS_BUILD_" should be removed
+	# Register /usr/bin/qemu-ARCH-static as the handler for ARM binaries in the kernel
+	docker run --rm --privileged multiarch/qemu-user-static:register --reset
+	curl -sSL https://github.com/multiarch/qemu-user-static/releases/download/v2.5.0/x86_64_qemu-$(QEMUARCH)-static.tar.xz | tar -xJ -C $(TEMP_DIR)
+	cd $(TEMP_DIR) && sed -i "s/CROSS_BUILD_//g" Dockerfile
 endif
 	cp dnsmasq.conf $(TEMP_DIR)
 	docker build -t $(REGISTRY)/kube-dnsmasq-$(ARCH):$(TAG) $(TEMP_DIR)