Dockerized build:

	$ make buildroot-image
	$ make out/minikube.iso

- Add en entry in the Makefile for building the container: buildroot-image
- Modify the minikube-iso target to out/minikube.iso to comply with the way
makefiles work.
- Also force the use of a docker container. If not needed
just run IN_DOCKER=1 make out/minikube.iso to avoid the invokation of a docker
container.
- Add some doc.
- The tag added to the generated image will allow to bypass the build of the
image as soon as the container is pushed to the minikube registry.

Makefile

@@ -22,6 +22,7 @@ INSTALL_SIZE ?= $(shell du out/minikube-windows-amd64.exe | cut -f1)
 BUILDROOT_BRANCH ?= 2016.08
 REGISTRY?=gcr.io/k8s-minikube
 DARWIN_BUILD_IMAGE ?= karalabe/xgo-1.7.3
+ISO_BUILD_IMAGE ?= $(REGISTRY)/buildroot-image
 
 ISO_VERSION ?= v1.0.7
 ISO_BUCKET ?= minikube/iso
@@ -85,7 +86,7 @@ out/minikube-linux-amd64: $(GOPATH)/src/$(ORG) pkg/minikube/assets/assets.go $(s
 out/minikube-windows-amd64.exe: $(GOPATH)/src/$(ORG) pkg/minikube/assets/assets.go $(shell $(MINIKUBEFILES))
 	CGO_ENABLED=0 GOARCH=amd64 GOOS=windows go build --installsuffix cgo -ldflags="$(MINIKUBE_LDFLAGS) $(K8S_VERSION_LDFLAGS)" -a -o $(BUILD_DIR)/minikube-windows-amd64.exe k8s.io/minikube/cmd/minikube
 
-minikube_iso:
+minikube_iso: # old target kept for making tests happy
 	echo $(ISO_VERSION) > deploy/iso/minikube-iso/board/coreos/minikube/rootfs-overlay/etc/VERSION
 	if [ ! -d $(BUILD_DIR)/buildroot ]; then \
 		mkdir -p $(BUILD_DIR); \
@@ -95,6 +96,15 @@ minikube_iso:
 	$(MAKE) -C $(BUILD_DIR)/buildroot
 	mv $(BUILD_DIR)/buildroot/output/images/rootfs.iso9660 $(BUILD_DIR)/minikube.iso
 
+out/minikube.iso: $(shell find deploy/iso/minikube-iso -type f)
+ifeq ($(IN_DOCKER),1)
+	$(MAKE) minikube_iso
+else
+	docker run --rm --workdir /mnt --volume $(CURDIR):/mnt \
+		--user $(shell id -u):$(shell id -g) --env HOME=/tmp --env IN_DOCKER=1 \
+		$(ISO_BUILD_IMAGE) /usr/bin/make out/minikube.iso
+endif
+
 test-iso:
 	go test -v $(REPOPATH)/test/integration --tags=iso --minikube-args="--iso-url=file://$(shell pwd)/out/buildroot/output/images/rootfs.iso9660"
 
@@ -175,16 +185,22 @@ release-localkube: out/localkube checksum
 	gsutil cp out/localkube.sha256 $(LOCALKUBE_BUCKET)/$(LOCALKUBE_VERSION)/localkube-linux-amd64.sha256
 
 .PHONY: update-releases
-update-releases: 
+update-releases:
 	gsutil cp deploy/minikube/k8s_releases.json gs://minikube/k8s_releases.json
 
-out/localkube-image: out/localkube
+localkube-image: out/localkube
 	# TODO(aprindle) make addons placed into container configurable
 	docker build -t $(REGISTRY)/localkube-image:$(TAG) -f deploy/docker/Dockerfile .
 	@echo ""
 	@echo "${REGISTRY}/localkube-image:$(TAG) succesfully built"
 	@echo "See https://github.com/kubernetes/minikube/tree/master/deploy/docker for instrucions on how to run image"
 
+buildroot-image: $(ISO_BUILD_IMAGE) # convenient alias to build the docker container
+$(ISO_BUILD_IMAGE): deploy/iso/minikube-iso/Dockerfile
+	docker build -t $@ -f $< $(dir $<)
+	@echo ""
+	@echo "$(@) succesfully built"
+
 .PHONY: release-iso
 release-iso: minikube_iso checksum
 	gsutil cp out/minikube.iso gs://$(ISO_BUCKET)/minikube-$(ISO_VERSION).iso

deploy/iso/minikube-iso/Dockerfile

+# Copyright 2016 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.
+
+# Beware ubuntu:16.10 and debian:testing have been tested and failed
+FROM ubuntu:16.04
+
+RUN apt-get update && apt-get install -y \
+		build-essential \
+		git \
+		wget \
+		cpio \
+		python \
+		unzip \
+		bc \
+		gcc-multilib \
+		automake \
+		libtool \
+		gnupg2 \
+		p7zip-full \
+		locales \
+		&& rm -rf /var/lib/apt/lists/*
+
+RUN localedef -i en_US -c -f UTF-8 -A /usr/share/locale/locale.alias en_US.UTF-8
+ENV LANG en_US.utf8
+
+# dumb init will allow us to interrupt the build with ^C
+RUN wget -O - https://github.com/Yelp/dumb-init/archive/v1.2.0.tar.gz | tar xvzf - \
+	&& make -C dumb-init-1.2.0 \
+	&& mv dumb-init-1.2.0/dumb-init /usr/bin \
+	&& rm -rf dumb-init-1.2.0
+
+ENTRYPOINT ["/usr/bin/dumb-init", "--"]
+CMD ["/bin/bash"]

deploy/iso/minikube-iso/README.md

@@ -42,9 +42,12 @@ Also be sure to have an UTF-8 locale set up in order to build the ISO.
 ```
 $ git clone https://github.com/kubernetes/minikube
 $ cd minikube
-$ make minikube_iso
+$ make buildroot-image
+$ make out/minikube.iso
 ```
 
+The build will occurs inside a docker container, if you want to do this
+baremetal, replace `make out/minikube.iso` with `IN_DOCKER=1 make out/minikube.iso`.
 The bootable ISO image will be available in `out/minikube.iso`.
 
 ### Testing local minikube-iso changes