add Dockerfile for clusterctl (#305)

Makefile

@@ -134,7 +134,7 @@ generate: manifests
 manifests:
 	go run vendor/sigs.k8s.io/controller-tools/cmd/controller-gen/main.go crd
 
-images: openstack-cluster-api-controller manifests
+images: openstack-cluster-api-controller clusterctl-image manifests
 
 openstack-cluster-api-controller: depend manager manifests
 ifeq ($(GOOS),linux)
@@ -145,10 +145,14 @@ else
 	$(error Please set GOOS=linux for building the image)
 endif
 
+clusterctl-image: generate fmt vet manifests
+	docker build . -f cmd/clusterctl/Dockerfile -t "$(REGISTRY)/openstack-cluster-api-clusterctl:$(VERSION)"
+
 upload-images: images
 	@echo "push images to $(REGISTRY)"
 	docker login -u="$(DOCKER_USERNAME)" -p="$(DOCKER_PASSWORD)";
 	docker push $(REGISTRY)/openstack-cluster-api-controller:$(VERSION)
+	docker push $(REGISTRY)/openstack-cluster-api-clusterctl:$(VERSION)
 
 version:
 	@echo ${VERSION}

cmd/clusterctl/Dockerfile

@@ -0,0 +1,32 @@
+# 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.
+
+# Build the cluster binary
+FROM golang:1.10.3 as builder
+
+# Copy in the go src
+WORKDIR /go/src/sigs.k8s.io/cluster-api-provider-openstack
+COPY pkg/    pkg/
+COPY cmd/    cmd/
+COPY vendor/ vendor/
+
+# Build
+RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -a -o clusterctl sigs.k8s.io/cluster-api-provider-openstack/cmd/clusterctl
+
+# Copy clusterctl into a thin image
+FROM debian:stretch-slim
+WORKDIR /root/
+
+RUN apt-get update && apt-get install -y ca-certificates openssh-client
+
+COPY --from=builder /go/src/sigs.k8s.io/cluster-api-provider-openstack/clusterctl .
+ENTRYPOINT ["./clusterctl"]