bazel: stamp version into build

cmd/kops/BUILD.bazel

@@ -115,6 +115,10 @@ go_binary(
     name = "kops",
     library = ":go_default_library",
     visibility = ["//visibility:public"],
+    x_defs = {
+        "k8s.io/kops.Version": "1.8.0-alpha.1",  # keep
+        "k8s.io/kops.GitVersion": "{BUILD_SCM_REVISION}",  # keep
+    },
 )
 
 go_test(

tools/bazel.rc

@@ -0,0 +1 @@
+build --workspace_status_command=./tools/get_workspace_status

tools/get_workspace_status

@@ -0,0 +1,30 @@
+#!/bin/bash
+
+# This script will be run bazel when building process starts to
+# generate key-value information that represents the status of the
+# workspace. The output should be like
+#
+# KEY1 VALUE1
+# KEY2 VALUE2
+#
+# If the script exits with non-zero code, it's considered as a failure
+# and the output will be discarded.
+
+# The code below presents an implementation that works for git repository
+git_rev=$(git rev-parse HEAD)
+if [[ $? != 0 ]];
+then
+    exit 1
+fi
+echo "BUILD_SCM_REVISION ${git_rev}"
+
+# Check whether there are any uncommited changes
+git diff-index --quiet HEAD --
+if [[ $? == 0 ]];
+then
+    tree_status="Clean"
+else
+    tree_status="Modified"
+fi
+echo "BUILD_SCM_STATUS ${tree_status}"
+