Add proper GCP config loader and refresher

Author: mbohlool

config/dateutil.py

@@ -0,0 +1,80 @@
+# Copyright 2017 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import datetime
+import math
+import re
+
+
+class TimezoneInfo(datetime.tzinfo):
+    def __init__(self, h, m):
+        self._name = "UTC"
+        if h != 0 and m != 0:
+            self._name += "%+03d:%2d" % (h, m)
+        self._delta = datetime.timedelta(hours=h, minutes=math.copysign(m, h))
+
+    def utcoffset(self, dt):
+        return self._delta
+
+    def tzname(self, dt):
+        return self._name
+
+    def dst(self, dt):
+        return datetime.timedelta(0)
+
+
+UTC = TimezoneInfo(0, 0)
+
+# ref https://www.ietf.org/rfc/rfc3339.txt
+_re_rfc3339 = re.compile(r"(\d\d\d\d)-(\d\d)-(\d\d)"        # full-date
+                         r"[ Tt]"                           # Separator
+                         r"(\d\d):(\d\d):(\d\d)([.,]\d+)?"  # partial-time
+                         r"([zZ ]|[-+]\d\d?:\d\d)?",        # time-offset
+                         re.VERBOSE + re.IGNORECASE)
+_re_timezone = re.compile(r"([-+])(\d\d?):?(\d\d)?")
+
+
+def parse_rfc3339(s):
+    if isinstance(s, datetime.datetime):
+        # no need to parse it, just make sure it has a timezone.
+        if not s.tzinfo:
+            return s.replace(tzinfo=UTC)
+        return s
+    groups = _re_rfc3339.search(s).groups()
+    dt = [0] * 7
+    for x in range(6):
+        dt[x] = int(groups[x])
+    if groups[6] is not None:
+        dt[6] = int(groups[6])
+    tz = UTC
+    if groups[7] is not None and groups[7] != 'Z' and groups[7] != 'z':
+        tz_groups = _re_timezone.search(groups[7]).groups()
+        hour = int(tz_groups[1])
+        minute = 0
+        if tz_groups[0] == "-":
+            hour *= -1
+        if tz_groups[2]:
+            minute = int(tz_groups[2])
+        tz = TimezoneInfo(hour, minute)
+    return datetime.datetime(
+        year=dt[0], month=dt[1], day=dt[2],
+        hour=dt[3], minute=dt[4], second=dt[5],
+        microsecond=dt[6], tzinfo=tz)
+
+
+def format_rfc3339(date_time):
+    if date_time.tzinfo is None:
+        date_time = date_time.replace(tzinfo=UTC)
+    date_time = date_time.astimezone(UTC)
+    return date_time.strftime('%Y-%m-%dT%H:%M:%SZ')

config/dateutil_test.py

@@ -0,0 +1,53 @@
+# Copyright 2016 The Kubernetes Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+from datetime import datetime
+
+from .dateutil import UTC, TimezoneInfo, format_rfc3339, parse_rfc3339
+
+
+class DateUtilTest(unittest.TestCase):
+
+    def _parse_rfc3339_test(self, st, y, m, d, h, mn, s):
+        actual = parse_rfc3339(st)
+        expected = datetime(y, m, d, h, mn, s, 0, UTC)
+        self.assertEqual(expected, actual)
+
+    def test_parse_rfc3339(self):
+        self._parse_rfc3339_test("2017-07-25T04:44:21Z",
+                                 2017, 7, 25, 4, 44, 21)
+        self._parse_rfc3339_test("2017-07-25 04:44:21Z",
+                                 2017, 7, 25, 4, 44, 21)
+        self._parse_rfc3339_test("2017-07-25T04:44:21",
+                                 2017, 7, 25, 4, 44, 21)
+        self._parse_rfc3339_test("2017-07-25T04:44:21z",
+                                 2017, 7, 25, 4, 44, 21)
+        self._parse_rfc3339_test("2017-07-25T04:44:21+03:00",
+                                 2017, 7, 25, 1, 44, 21)
+        self._parse_rfc3339_test("2017-07-25T04:44:21-03:00",
+                                 2017, 7, 25, 7, 44, 21)
+
+    def test_format_rfc3339(self):
+        self.assertEqual(
+            format_rfc3339(datetime(2017, 7, 25, 4, 44, 21, 0, UTC)),
+            "2017-07-25T04:44:21Z")
+        self.assertEqual(
+            format_rfc3339(datetime(2017, 7, 25, 4, 44, 21, 0,
+                                    TimezoneInfo(2, 0))),
+            "2017-07-25T02:44:21Z")
+        self.assertEqual(
+            format_rfc3339(datetime(2017, 7, 25, 4, 44, 21, 0,
+                                    TimezoneInfo(-2, 30))),
+            "2017-07-25T07:14:21Z")

config/kube_config.py

@@ -14,17 +14,21 @@
 
 import atexit
 import base64
+import datetime
 import os
 import tempfile
 
+import google.auth
+import google.auth.transport.requests
 import urllib3
 import yaml
-from google.oauth2.credentials import Credentials
 
 from kubernetes.client import ApiClient, ConfigurationObject, configuration
 
 from .config_exception import ConfigException
+from .dateutil import UTC, format_rfc3339, parse_rfc3339
 
+EXPIRY_SKEW_PREVENTION_DELAY = datetime.timedelta(minutes=5)
 KUBE_CONFIG_DEFAULT_LOCATION = os.environ.get('KUBECONFIG', '~/.kube/config')
 _temp_files = {}
 
@@ -54,6 +58,11 @@ def _create_temp_file_with_content(content):
     return name
 
 
+def _is_expired(expiry):
+    return ((parse_rfc3339(expiry) + EXPIRY_SKEW_PREVENTION_DELAY) <=
+            datetime.datetime.utcnow().replace(tzinfo=UTC))
+
+
 class FileOrData(object):
     """Utility class to read content of obj[%data_key_name] or file's
      content of obj[%file_key_name] and represent it as file or data.
@@ -110,19 +119,26 @@ class KubeConfigLoader(object):
     def __init__(self, config_dict, active_context=None,
                  get_google_credentials=None,
                  client_configuration=configuration,
-                 config_base_path=""):
+                 config_base_path="",
+                 config_persister=None):
         self._config = ConfigNode('kube-config', config_dict)
         self._current_context = None
         self._user = None
         self._cluster = None
         self.set_active_context(active_context)
         self._config_base_path = config_base_path
+        self._config_persister = config_persister
+
+        def _refresh_credentials():
+            credentials, project_id = google.auth.default()
+            request = google.auth.transport.requests.Request()
+            credentials.refresh(request)
+            return credentials
+
         if get_google_credentials:
             self._get_google_credentials = get_google_credentials
         else:
-            self._get_google_credentials = lambda: (
-                GoogleCredentials.get_application_default()
-                .get_access_token().access_token)
+            self._get_google_credentials = _refresh_credentials
         self._client_configuration = client_configuration
 
     def set_active_context(self, context_name=None):
@@ -166,16 +182,32 @@ def _load_authentication(self):
     def _load_gcp_token(self):
         if 'auth-provider' not in self._user:
             return
-        if 'name' not in self._user['auth-provider']:
+        provider = self._user['auth-provider']
+        if 'name' not in provider:
             return
-        if self._user['auth-provider']['name'] != 'gcp':
+        if provider['name'] != 'gcp':
             return
-        # Ignore configs in auth-provider and rely on GoogleCredentials
-        # caching and refresh mechanism.
-        # TODO: support gcp command based token ("cmd-path" config).
-        self.token = "Bearer %s" % self._get_google_credentials()
+
+        if (('config' not in provider) or
+                ('access-token' not in provider['config']) or
+                ('expiry' in provider['config'] and
+                 _is_expired(provider['config']['expiry']))):
+            # token is not available or expired, refresh it
+            self._refresh_gcp_token()
+
+        self.token = "Bearer %s" % provider['config']['access-token']
         return self.token
 
+    def _refresh_gcp_token(self):
+        if 'config' not in self._user['auth-provider']:
+            self._user['auth-provider'].value['config'] = {}
+        provider = self._user['auth-provider']['config']
+        credentials = self._get_google_credentials()
+        provider.value['access-token'] = credentials.token
+        provider.value['expiry'] = format_rfc3339(credentials.expiry)
+        if self._config_persister:
+            self._config_persister(self._config.value)
+
     def _load_user_token(self):
         token = FileOrData(
             self._user, 'tokenFile', 'token',
@@ -299,7 +331,8 @@ def list_kube_config_contexts(config_file=None):
 
 
 def load_kube_config(config_file=None, context=None,
-                     client_configuration=configuration):
+                     client_configuration=configuration,
+                     persist_config=True):
     """Loads authentication and cluster information from kube-config file
     and stores them in kubernetes.client.configuration.
 
@@ -308,21 +341,35 @@ def load_kube_config(config_file=None, context=None,
         from config file will be used.
     :param client_configuration: The kubernetes.client.ConfigurationObject to
         set configs to.
+    :param persist_config: If True, config file will be updated when changed
+        (e.g GCP token refresh).
     """
 
     if config_file is None:
         config_file = os.path.expanduser(KUBE_CONFIG_DEFAULT_LOCATION)
 
+    config_persister = None
+    if persist_config:
+        def _save_kube_config(config_map):
+            with open(config_file, 'w') as f:
+                yaml.safe_dump(config_map, f, default_flow_style=False)
+        config_persister = _save_kube_config
+
     _get_kube_config_loader_for_yaml_file(
         config_file, active_context=context,
-        client_configuration=client_configuration).load_and_set()
+        client_configuration=client_configuration,
+        config_persister=config_persister).load_and_set()
 
 
-def new_client_from_config(config_file=None, context=None):
+def new_client_from_config(
+        config_file=None,
+        context=None,
+        persist_config=True):
     """Loads configuration the same as load_kube_config but returns an ApiClient
     to be used with any API object. This will allow the caller to concurrently
     talk with multiple clusters."""
     client_config = ConfigurationObject()
     load_kube_config(config_file=config_file, context=context,
-                     client_configuration=client_config)
+                     client_configuration=client_config,
+                     persist_config=persist_config)
     return ApiClient(config=client_config)