Make dockerized build work when golang isn't installed.

hack/lib/init.sh

@@ -39,4 +39,4 @@ source "${KUBE_ROOT}/hack/lib/version.sh"
 source "${KUBE_ROOT}/hack/lib/golang.sh"
 source "${KUBE_ROOT}/hack/lib/etcd.sh"
 
-KUBE_OUTPUT_HOSTBIN="${KUBE_OUTPUT_BINPATH}/$(kube::golang::host_platform)"
+KUBE_OUTPUT_HOSTBIN="${KUBE_OUTPUT_BINPATH}/$(kube::util::host_platform)"

hack/lib/util.sh

@@ -36,3 +36,46 @@ kube::util::wait_for_url() {
   kube::log::error "Timed out waiting for ${url}"
   return 1
 }
+
+# This figures out the host platform without relying on golang.  We need this as
+# we don't want a golang install to be a prerequisite to building yet we need
+# this info to figure out where the final binaries are placed.
+kube::util::host_platform() {
+  local host_os
+  local host_arch
+  case "$(uname -s)" in
+    Darwin)
+      host_os=darwin
+      ;;
+    Linux)
+      host_os=linux
+      ;;
+    *)
+      kube::log::error "Unsupported host OS.  Must be Linux or Mac OS X."
+      exit 1
+      ;;
+  esac
+
+  case "$(uname -m)" in
+    x86_64*)
+      host_arch=amd64
+      ;;
+    i?86_64*)
+      host_arch=amd64
+      ;;
+    amd64*)
+      host_arch=amd64
+      ;;
+    arm*)
+      host_arch=arm
+      ;;
+    i?86*)
+      host_arch=x86
+      ;;
+    *)
+      kube::log::error "Unsupported host arch. Must be x86_64, 386 or arm."
+      exit 1
+      ;;
+  esac
+  echo "${host_os}/${host_arch}"
+}