feat: Make GAPIC Bazel rules production ready

BUILD.bazel

@@ -1,5 +1,6 @@
 load("//:gapic_generator_python.bzl", "pandoc_binary", "pandoc_toolchain")
 load("@gapic_generator_python_pip_deps//:requirements.bzl", "requirement")
+load("@bazel_tools//tools/python:toolchain.bzl", "py_runtime_pair")
 
 toolchain_type(
     name = "pandoc_toolchain_type",
@@ -23,14 +24,37 @@ pandoc_toolchain(
 )
 
 pandoc_binary(
-    name = "pandoc_binary"
+    name = "pandoc_binary",
+)
+
+config_setting(
+    name = "gapic_gen_python_3_6",
+    values = {"define": "gapic_gen_python=3.6"},
+)
+
+py_runtime(
+    name = "pyenv3_runtime",
+    interpreter = ":pyenv3wrapper.sh",
+    python_version="PY3",
+)
+
+py_runtime_pair(
+    name = "pyenv3_runtime_pair",
+    py3_runtime = ":pyenv3_runtime",
+)
+
+toolchain(
+    name = "pyenv3_toolchain",
+    toolchain = ":pyenv3_runtime_pair",
+    toolchain_type = "@bazel_tools//tools/python:toolchain_type",
 )
 
 py_binary(
     name = "gapic_plugin",
     srcs = glob(["gapic/**/*.py"]),
     data = [":pandoc_binary"] + glob(["gapic/**/*.j2"]),
     main = "gapic/cli/generate_with_pandoc.py",
+    python_version = "PY3",
     visibility = ["//visibility:public"],
     deps = [
         "@com_google_protobuf//:protobuf_python",
@@ -42,6 +66,8 @@ py_binary(
         requirement("MarkupSafe"),
         requirement("pypandoc"),
         requirement("PyYAML"),
-    ],
-    python_version = "PY3",
-)
+    ] + select({
+        ":gapic_gen_python_3_6": [requirement("dataclasses")],
+        "//conditions:default": [],
+    }),
+)

WORKSPACE

@@ -43,7 +43,7 @@ protobuf_deps()
 
 #
 # Import grpc as a native bazel dependency. This avoids duplication and also
-# spedds up loading phase a lot (otherwise python_rules will be building grpcio
+# speeds up loading phase a lot (otherwise python_rules will be building grpcio
 # from sources in a single-core speed, which takes around 5 minutes on a regular
 # workstation)
 #

gapic/cli/generate_with_pandoc.py

@@ -5,4 +5,5 @@
 if __name__ == '__main__':
     os.environ['PYPANDOC_PANDOC'] = os.path.join(
         os.path.abspath(__file__).rsplit("gapic", 1)[0], "pandoc")
+    os.environ['LC_ALL'] = 'C.UTF-8'
     generate.generate()

pyenv3wrapper.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+
+HOME_DIR=$(getent passwd "$(whoami)" | cut -d: -f6)
+exec "$HOME_DIR/.pyenv/shims/python3" "$@"

requirements.txt

@@ -6,3 +6,4 @@ MarkupSafe==1.1.1
 protobuf==3.11.3
 pypandoc==1.5
 PyYAML==5.3.1
+dataclasses==0.6