python/kubernetes/config/kube_config.py
mbohlool b888000b4a - Add context switch to kube config loader
- Refactor kube config loader to be able to test it
- Add test for kube config loader
2016-12-01 16:08:14 -08:00

265 lines
9.5 KiB
Python

# 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 atexit
import base64
import os
import tempfile
import urllib3
import yaml
from kubernetes.client import configuration
from oauth2client.client import GoogleCredentials
from .config_exception import ConfigException
_temp_files = {}
def _cleanup_temp_files():
for temp_file in _temp_files.values():
os.remove(temp_file)
def _create_temp_file_with_content(content):
if len(_temp_files) == 0:
atexit.register(_cleanup_temp_files)
# Because we may change context several times, try to remember files we
# created and reuse them at a small memory cost.
content_key = str(content)
if content_key in _temp_files:
return _temp_files[content_key]
_, name = tempfile.mkstemp()
_temp_files[content_key] = name
with open(name, 'wb') as fd:
fd.write(content.encode() if isinstance(content, str) else content)
return name
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.
Note that the data is preferred. The obj[%file_key_name] will be used iff
obj['%data_key_name'] is not set or empty. Assumption is file content is
raw data and data field is base64 string."""
def __init__(self, obj, file_key_name, data_key_name=None):
if not data_key_name:
data_key_name = file_key_name + "-data"
self._file = None
self._data = None
if data_key_name in obj:
self._data = obj[data_key_name]
elif file_key_name in obj:
self._file = obj[file_key_name]
def as_file(self):
"""If obj[%data_key_name] exists, return name of a file with base64
decoded obj[%data_key_name] content otherwise obj[%file_key_name]."""
use_data_if_no_file = not self._file and self._data
if use_data_if_no_file:
self._file = _create_temp_file_with_content(
base64.decodestring(self._data.encode()))
return self._file
def as_data(self):
"""If obj[%data_key_name] exists, Return obj[%data_key_name] otherwise
base64 encoded string of obj[%file_key_name] file content."""
use_file_if_no_data = not self._data and self._file
if use_file_if_no_data:
with open(self._file) as f:
self._data = bytes.decode(
base64.encodestring(str.encode(f.read())))
return self._data
class KubeConfigLoader(object):
def __init__(self, config_dict, active_context=None,
get_google_credentials=None, client_configuration=None):
self._config = ConfigNode('kube-config', config_dict)
self._current_context = None
self._user = None
self._cluster = None
self.set_active_context(active_context)
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)
if client_configuration:
self._client_configuration = client_configuration
else:
self._client_configuration = configuration
def set_active_context(self, context_name=None):
if context_name is None:
context_name = self._config['current-context']
self._current_context = self._config['contexts'].get_with_name(
context_name)
if self._current_context['context'].safe_get('user'):
self._user = self._config['users'].get_with_name(
self._current_context['context']['user'])['user']
else:
self._user = None
self._cluster = self._config['clusters'].get_with_name(
self._current_context['context']['cluster'])['cluster']
def _load_authentication(self):
"""Read authentication from kube-config user section if exists.
This function goes through various authentication methods in user
section of kube-config and stops if it finds a valid authentication
method. The order of authentication methods is:
1. GCP auth-provider
2. token_data
3. token field (point to a token file)
4. username/password
"""
if not self._user:
return
if self._load_gcp_token():
return
if self._load_user_token():
return
self._load_user_pass_token()
def _load_gcp_token(self):
if 'auth-provider' not in self._user:
return
if 'name' not in self._user['auth-provider']:
return
if self._user['auth-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 = self._get_google_credentials()
return self.token
def _load_user_token(self):
token = FileOrData(self._user, 'tokenFile', 'token').as_data()
if token:
self.token = token
return True
def _load_user_pass_token(self):
if 'username' in self._user and 'password' in self._user:
self.token = urllib3.util.make_headers(
basic_auth=(self._user['username'] + ':' +
self._user['password'])).get('authorization')
return True
def _load_cluster_info(self):
if 'server' in self._cluster:
self.host = self._cluster['server']
if self.host.startswith("https"):
self.ssl_ca_cert = FileOrData(
self._cluster, 'certificate-authority').as_file()
self.cert_file = FileOrData(
self._user, 'client-certificate').as_file()
self.key_file = FileOrData(self._user, 'client-key').as_file()
def _set_config(self):
if 'token' in self.__dict__:
self._client_configuration.api_key['authorization'] = self.token
# copy these keys directly from self to configuration object
keys = ['host', 'ssl_ca_cert', 'cert_file', 'key_file']
for key in keys:
if key in self.__dict__:
setattr(self._client_configuration, key, getattr(self, key))
def load_and_set(self):
self._load_authentication()
self._load_cluster_info()
self._set_config()
def list_contexts(self):
return [context.value for context in self._config['contexts']]
@property
def current_context(self):
return self._current_context.value
class ConfigNode(object):
"""Remembers each config key's path and construct a relevant exception
message in case of missing keys. The assumption is all access keys are
present in a well-formed kube-config."""
def __init__(self, name, value):
self.name = name
self.value = value
def __contains__(self, key):
return key in self.value
def __len__(self):
return len(self.value)
def safe_get(self, key):
if (isinstance(self.value, list) and isinstance(key, int) or
key in self.value):
return self.value[key]
def __getitem__(self, key):
v = self.safe_get(key)
if not v:
raise ConfigException(
'Invalid kube-config file. Expected key %s in %s'
% (key, self.name))
if isinstance(v, dict) or isinstance(v, list):
return ConfigNode('%s/%s' % (self.name, key), v)
else:
return v
def get_with_name(self, name):
if not isinstance(self.value, list):
raise ConfigException(
'Invalid kube-config file. Expected %s to be a list'
% self.name)
for v in self.value:
if 'name' not in v:
raise ConfigException(
'Invalid kube-config file. '
'Expected all values in %s list to have \'name\' key'
% self.name)
if v['name'] == name:
return ConfigNode('%s[name=%s]' % (self.name, name), v)
raise ConfigException(
'Invalid kube-config file. '
'Expected object with name %s in %s list' % (name, self.name))
def list_kube_config_contexts(config_file):
with open(config_file) as f:
loader = KubeConfigLoader(config_dict=yaml.load(f))
return loader.list_contexts(), loader.current_context
def load_kube_config(config_file, context=None):
"""Loads authentication and cluster information from kube-config file
and stores them in kubernetes.client.configuration.
:param config_file: Name of the kube-config file.
:param context: set the active context. If is set to None, current_context
from config file will be used.
"""
with open(config_file) as f:
KubeConfigLoader(
config_dict=yaml.load(f), active_context=context).load_and_set()