Add target to build the kvm driver in docker

Makefile

@@ -30,6 +30,8 @@ HYPERKIT_BUILD_IMAGE 	?= karalabe/xgo-1.10.x
 # NOTE: "latest" as of 2018-12-04. kube-cross images aren't updated as often as Kubernetes
 BUILD_IMAGE 	?= k8s.gcr.io/kube-cross:v1.11.1-1
 ISO_BUILD_IMAGE ?= $(REGISTRY)/buildroot-image
+KVM_BUILD_IMAGE ?= $(REGISTRY)/kvm-build-image
+
 ISO_BUCKET ?= minikube/iso
 
 MINIKUBE_VERSION ?= $(ISO_VERSION)
@@ -38,6 +40,8 @@ MINIKUBE_UPLOAD_LOCATION := gs://${MINIKUBE_BUCKET}
 
 KERNEL_VERSION ?= 4.16.14
 
+GO_VERSION ?= $(shell go version | cut -d' ' -f3 | sed -e 's/go//')
+
 GOOS ?= $(shell go env GOOS)
 GOARCH ?= $(shell go env GOARCH)
 GOPATH ?= $(shell go env GOPATH)
@@ -256,7 +260,7 @@ out/minikube-%-amd64.tar.gz: $$(TAR_TARGETS_$$*) $(TAR_TARGETS_ALL)
 	tar -cvf $@ $^
 
 .PHONY: cross-tars
-cross-tars: out/minikube-windows-amd64.tar.gz out/minikube-linux-amd64.tar.gz out/minikube-darwin-amd64.tar.gz
+cross-tars: kvm_in_docker out/minikube-windows-amd64.tar.gz out/minikube-linux-amd64.tar.gz out/minikube-darwin-amd64.tar.gz
 
 out/minikube-installer.exe: out/minikube-windows-amd64.exe
 	rm -rf out/windows_tmp
@@ -349,10 +353,22 @@ out/docker-machine-driver-kvm2:
 		k8s.io/minikube/cmd/drivers/kvm
 	chmod +X $@
 
+kvm-image: $(KVM_BUILD_IMAGE) # convenient alias to build the docker container
+$(KVM_BUILD_IMAGE): installers/linux/kvm/Dockerfile
+	docker build --build-arg "GO_VERSION=$(GO_VERSION)" -t $@ -f $< $(dir $<)
+	@echo ""
+	@echo "$(@) successfully built"
+
+kvm_in_docker:
+	docker inspect $(KVM_BUILD_IMAGE) || $(MAKE) $(KVM_BUILD_IMAGE)
+	rm -f out/docker-machine-driver-kvm2
+	docker run --rm -v $(PWD):/go/src/k8s.io/minikube $(KVM_BUILD_IMAGE) \
+		/usr/bin/make -C /go/src/k8s.io/minikube out/docker-machine-driver-kvm2
+
 .PHONY: install-kvm
 install-kvm: out/docker-machine-driver-kvm2
 	cp out/docker-machine-driver-kvm2 $(GOBIN)/docker-machine-driver-kvm2
 
 .PHONY: release-kvm-driver
-release-kvm-driver: install-kvm
+release-kvm-driver: kvm_in_docker install-kvm
 	gsutil cp $(GOBIN)/docker-machine-driver-kvm2 gs://minikube/drivers/kvm/$(VERSION)/

installers/linux/kvm/Dockerfile

@@ -0,0 +1,31 @@
+# Copyright 2019 The Kubernetes Authors All rights reserved.
+#
+# 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.
+
+FROM gcr.io/gcp-runtimes/ubuntu_16_0_4
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+		gcc \
+		libc6-dev \
+		make \
+		pkg-config \
+		curl \
+		libvirt-dev \
+	&& rm -rf /var/lib/apt/lists/*
+
+ARG GO_VERSION
+
+RUN curl -sSL https://golang.org/dl/go${GO_VERSION}.linux-amd64.tar.gz | tar -C /usr/local -xzf -
+
+ENV GOPATH /go
+ENV PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/go/bin:/go/bin