Mark stamper and reverser as python 3 (#531)

* Mark stamper and reverser as python 3

* Switch host force flags to python 3

* buildifier

.bazelrc

@@ -21,9 +21,9 @@ test --test_output=errors --workspace_status_command="bash print-workspace-statu
 # Also, force host binaries to use py2.
 # Note these flags will only work with Bazel 0.25.0 or above.
 build --incompatible_use_python_toolchains
-build --host_force_python=PY2
+build --host_force_python=PY3
 test --incompatible_use_python_toolchains
-test --host_force_python=PY2
+test --host_force_python=PY3
 run --incompatible_use_python_toolchains
-run --host_force_python=PY2
+run --host_force_python=PY3
 

k8s/BUILD

@@ -33,13 +33,17 @@ par_binary(
     name = "stamper",
     srcs = ["stamper.py"],
     main = "stamper.py",
+    python_version = "PY3",
+    srcs_version = "PY3",
     visibility = ["//visibility:public"],
 )
 
 par_binary(
     name = "reverser",
     srcs = ["reverser.py"],
     main = "reverser.py",
+    python_version = "PY3",
+    srcs_version = "PY3",
     visibility = ["//visibility:public"],
     deps = select({
         "@bazel_tools//tools/python:PY2": ["@com_github_yaml_pyyaml//:yaml"],

k8s/reverser.py

@@ -13,6 +13,8 @@
 # limitations under the License.
 """Reverses the object order in a multi-document yaml."""
 
+from __future__ import absolute_import
+from __future__ import division
 from __future__ import print_function
 
 import argparse

k8s/stamper.py

@@ -13,6 +13,9 @@
 # limitations under the License.
 """Resolve stamp variables."""
 
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
 import argparse
 import sys