Overhaul Makefile and Dockerfile

Trying to standardize builds across architectures.  We wrote this basic
Makefile/Dockerfile template for another container, but it works well, so reuse
it here.

.gitignore

@@ -0,0 +1 @@
+/bin

Dockerfile

@@ -1,7 +1,9 @@
 FROM gcr.io/google_containers/ubuntu-slim:0.1
 
+ARG ARCH
+ADD bin/git-sync-${ARCH} /git-sync
+
 ENV GIT_SYNC_DEST /git
-VOLUME ["/git"]
 
 RUN apt-get update && \
   apt-get install -y git ca-certificates --no-install-recommends && \
@@ -9,8 +11,6 @@ RUN apt-get update && \
   apt-get clean -y && \
   rm -rf /var/lib/apt/lists/*
 
-COPY git-sync /git-sync
-
 # Move the existing SSH binary, then replace it with the wrapper script
 RUN mv /usr/bin/ssh /usr/bin/ssh-binary
 COPY ssh-wrapper.sh /usr/bin/ssh

Makefile

@@ -1,17 +1,89 @@
-all: push
+# Copyright 2016 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 
-# 0.0 shouldn't clobber any released builds
+.PHONY: all push push-legacy container clean
-TAG = 0.0
-PREFIX = gcr.io/google_containers/git-sync
 
-binary: main.go
+REGISTRY ?= gcr.io/google_containers
-	CGO_ENABLED=0 GOOS=linux godep go build -a -installsuffix cgo -ldflags '-w' -o git-sync
+IMAGE = $(REGISTRY)/git-sync-$(ARCH)
+LEGACY_AMD64_IMAGE = $(REGISTRY)/git-sync
 
-container: binary
+TAG = 1.0
-	docker build -t $(PREFIX):$(TAG) .
 
-push: container
+# Architectures supported: amd64, arm, arm64 and ppc64le
-	gcloud docker push $(PREFIX):$(TAG)
+ARCH ?= amd64
+
+# TODO: get a base image for non-x86 archs
+#       arm arm64 ppc64le
+ALL_ARCH = amd64
+
+KUBE_CROSS_IMAGE ?= gcr.io/google_containers/kube-cross
+KUBE_CROSS_VERSION ?= v1.6.3-2
+
+GO_PKG = k8s.io/git-sync
+BIN = git-sync
+SRCS = main.go
+
+# If you want to build all containers, see the 'all-container' rule.
+# If you want to build AND push all containers, see the 'all-push' rule.
+all: all-build
+
+sub-container-%:
+	$(MAKE) ARCH=$* container
+
+sub-push-%:
+	$(MAKE) ARCH=$* push
+
+all-build: $(addprefix bin/$(BIN)-,$(ALL_ARCH))
+
+all-container: $(addprefix sub-container-,$(ALL_ARCH))
+
+all-push: $(addprefix sub-push-,$(ALL_ARCH))
+
+build: bin/$(BIN)-$(ARCH)
+
+bin/$(BIN)-$(ARCH): $(SRCS)
+	mkdir -p bin
+	docker run                                      \
+	    -u $$(id -u):$$(id -g)                      \
+	    -v $$(pwd):/go/src/$(GO_PKG)                \
+	    $(KUBE_CROSS_IMAGE):$(KUBE_CROSS_VERSION)   \
+	    /bin/bash -c "                              \
+	        cd /go/src/$(GO_PKG) &&                 \
+	        CGO_ENABLED=0 godep go build            \
+	        -installsuffix cgo                      \
+	        -ldflags '-w'                           \
+	        -o $@"
+
+container: .container-$(ARCH)
+.container-$(ARCH): bin/$(BIN)-$(ARCH)
+	docker build -t $(IMAGE):$(TAG) --build-arg ARCH=$(ARCH) .
+ifeq ($(ARCH),amd64)
+	docker tag $(IMAGE):$(TAG) $(LEGACY_AMD64_IMAGE):$(TAG)
+endif
+	touch $@
+
+push: .push-$(ARCH)
+.push-$(ARCH): .container-$(ARCH)
+	gcloud docker push $(IMAGE):$(TAG)
+	touch $@
+
+push-legacy: .push-legacy-$(ARCH)
+.push-legacy-$(ARCH): .container-$(ARCH)
+ifeq ($(ARCH),amd64)
+	gcloud docker push $(LEGACY_AMD64_IMAGE):$(TAG)
+endif
+	touch $@
 
 clean:
-	docker rmi -f $(PREFIX):$(TAG) || true
+	rm -rf .container-* .push-* bin/