scripts: clean up genproto

Rather than copying in .proto files, use the same symlink
trick we do for doing the actual etcd build.

Also check for exact version of protoc early on.

scripts/genproto.sh

@@ -10,41 +10,42 @@ if ! [[ "$0" =~ "scripts/genproto.sh" ]]; then
 	exit 255
 fi
 
+# for now, be conservative about what version of protoc we expect
+if ! [[ $(protoc --version) =~ "3.0.0" ]]; then
+	echo "could not find protoc 3.0.0, is it installed + in PATH?"
+	exit 255
+fi
+
 PREFIX="github.com/coreos/etcd/Godeps/_workspace/src"
+ESCAPED_PREFIX=$(echo $PREFIX | sed -e 's/[\/&]/\\&/g')
+
+# directories containing protos to be built
 DIRS="./wal/walpb ./etcdserver/etcdserverpb ./snap/snappb ./raft/raftpb ./storage/storagepb"
 
+# exact version of protoc-gen-gogo to build
 SHA="932b70afa8b0bf4a8e167fdf0c3367cebba45903"
 
-if ! protoc --version > /dev/null; then
-	echo "could not find protoc, is it installed + in PATH?"
-	exit 255
-fi
-
-# Ensure we have the right version of protoc-gen-gogo by building it every time.
-# TODO(jonboulle): vendor this instead of `go get`ting it.
+# set up self-contained GOPATH for building
 export GOPATH=${PWD}/gopath
 export GOBIN=${PWD}/bin
-go get github.com/gogo/protobuf/{proto,protoc-gen-gogo,gogoproto}
-pushd ${GOPATH}/src/github.com/gogo/protobuf/
-	git reset --hard ${SHA}
-	make install
-popd
-
 export PATH="${GOBIN}:${PATH}"
 
-# copy all proto dependencies inside etcd to gopath
-for dir in ${DIRS}; do
-	mkdir -p ${GOPATH}/src/github.com/coreos/etcd/${dir}
-	pushd ${dir}
-		cp *.proto ${GOPATH}/src/github.com/coreos/etcd/${dir}
-	popd
-done
-
 COREOS_ROOT="${GOPATH}/src/github.com/coreos"
+ETCD_ROOT="${COREOS_ROOT}/etcd"
 GOGOPROTO_ROOT="${GOPATH}/src/github.com/gogo/protobuf"
 GOGOPROTO_PATH="${GOGOPROTO_ROOT}:${GOGOPROTO_ROOT}/protobuf"
 
-ESCAPED_PREFIX=$(echo $PREFIX | sed -e 's/[\/&]/\\&/g')
+rm -f "${ETCD_ROOT}"
+mkdir -p "${COREOS_ROOT}"
+ln -s "${PWD}" "${ETCD_ROOT}"
+
+# Ensure we have the right version of protoc-gen-gogo by building it every time.
+# TODO(jonboulle): vendor this instead of `go get`ting it.
+go get github.com/gogo/protobuf/{proto,protoc-gen-gogo,gogoproto}
+pushd "${GOGOPROTO_ROOT}"
+	git reset --hard "${SHA}"
+	make install
+popd
 
 for dir in ${DIRS}; do
 	pushd ${dir}