Support connecting to multiple clusters

Author: mbohlool

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 - Add context switch to kube config loader #46 
 - Add default kube config location #64
+- Add suport for accessing multiple clusters #7
 - Bugfix: Python client does not resolve relative paths in kubeconfig #68
 - Bugfix: `read_namespaced_pod_log` get None response #57
 - Improved test coverage #54

examples/example4.py

@@ -14,6 +14,9 @@
 
 from kubernetes import client, config
 from kubernetes.client import configuration
+# install pick using "pip install pick". It is not included
+# as a dependency because it only used in examples
+from pick import pick
 
 
 def main():
@@ -22,25 +25,12 @@ def main():
         print("Cannot find any context in kube-config file.")
         return
     contexts = [context['name'] for context in contexts]
-    active_context = active_context['name']
-    for i, context in enumerate(contexts):
-        format_str = "%d. %s"
-        if context == active_context:
-            format_str = "* " + format_str
-        print(format_str % (i, context))
-    context = input("Enter context number: ")
-    context = int(context)
-    if context not in range(len(contexts)):
-        print(
-            "Number out of range. Using default context %s." %
-            active_context)
-        context_name = active_context
-    else:
-        context_name = contexts[context]
-
+    active_index = contexts.index(active_context['name'])
+    option, _ = pick(contexts, title="Pick the context to load",
+                     default_index=active_index)
     # Configs can be set in Configuration class directly or using helper
     # utility
-    config.load_kube_config(context=context_name)
+    config.load_kube_config(context=option)
 
     print("Active host is %s" % configuration.host)
 

examples/multiple_clusters.py

@@ -0,0 +1,51 @@
+# 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.
+
+from kubernetes import client, config
+# install pick using "pip install pick". It is not included
+# as a dependency because it only used in examples
+from pick import pick
+
+
+def main():
+
+    contexts, active_context = config.list_kube_config_contexts()
+    if not contexts:
+        print("Cannot find any context in kube-config file.")
+        return
+    contexts = [context['name'] for context in contexts]
+    active_index = contexts.index(active_context['name'])
+    cluster1, first_index = pick(contexts, title="Pick the first context",
+                                 default_index=active_index)
+    cluster2, _ = pick(contexts, title="Pick the second context",
+                       default_index=first_index)
+
+    client1 = client.CoreV1Api(
+        api_client=config.new_client_from_config(context=cluster1))
+    client2 = client.CoreV1Api(
+        api_client=config.new_client_from_config(context=cluster2))
+
+    print("\nList of pods on %s:" % cluster1)
+    for i in client1.list_pod_for_all_namespaces().items:
+        print("%s\t%s\t%s" %
+              (i.status.pod_ip, i.metadata.namespace, i.metadata.name))
+
+    print("\n\nList of pods on %s:" % cluster2)
+    for i in client2.list_pod_for_all_namespaces().items:
+        print("%s\t%s\t%s" %
+              (i.status.pod_ip, i.metadata.namespace, i.metadata.name))
+
+
+if __name__ == '__main__':
+    main()

kubernetes/.swagger-codegen-ignore

@@ -5,3 +5,7 @@ test-requirements.txt
 setup.py
 .travis.yml
 tox.ini
+client/__init__.py
+client/api_client.py
+client/configuration.py
+client/rest.py

kubernetes/client/__init__.py

@@ -288,6 +288,4 @@
 # import ApiClient
 from .api_client import ApiClient
 
-from .configuration import Configuration
-
-configuration = Configuration()
+from .configuration import Configuration, ConfigurationObject, configuration

kubernetes/client/api_client.py

@@ -38,7 +38,7 @@
 from six import PY3, integer_types, iteritems, text_type
 from six.moves.urllib.parse import quote
 
-from .configuration import Configuration
+from .configuration import configuration
 
 
 class ApiClient(object):
@@ -58,17 +58,19 @@ class ApiClient(object):
     :param header_name: a header to pass when making calls to the API.
     :param header_value: a header value to pass when making calls to the API.
     """
-    def __init__(self, host=None, header_name=None, header_value=None, cookie=None):
+    def __init__(self, host=None, header_name=None, header_value=None,
+                 cookie=None, config=configuration):
 
         """
         Constructor of the class.
         """
-        self.rest_client = RESTClientObject()
+        self.config = config
+        self.rest_client = RESTClientObject(config=self.config)
         self.default_headers = {}
         if header_name is not None:
             self.default_headers[header_name] = header_value
         if host is None:
-            self.host = Configuration().host
+            self.host = self.config.host
         else:
             self.host = host
         self.cookie = cookie
@@ -499,13 +501,12 @@ def update_params_for_auth(self, headers, querys, auth_settings):
         :param querys: Query parameters tuple list to be updated.
         :param auth_settings: Authentication setting identifiers list.
         """
-        config = Configuration()
 
         if not auth_settings:
             return
 
         for auth in auth_settings:
-            auth_setting = config.auth_settings().get(auth)
+            auth_setting = self.config.auth_settings().get(auth)
             if auth_setting:
                 if not auth_setting['value']:
                     continue
@@ -526,9 +527,7 @@ def __deserialize_file(self, response):
         :param response:  RESTResponse.
         :return: file path.
         """
-        config = Configuration()
-
-        fd, path = tempfile.mkstemp(dir=config.temp_folder_path)
+        fd, path = tempfile.mkstemp(dir=self.config.temp_folder_path)
         os.close(fd)
         os.remove(path)
 

kubernetes/client/configuration.py

@@ -33,18 +33,7 @@
 from six.moves import http_client as httplib
 
 
-def singleton(cls, *args, **kw):
-    instances = {}
-
-    def _singleton():
-        if cls not in instances:
-            instances[cls] = cls(*args, **kw)
-        return instances[cls]
-    return _singleton
-
-
-@singleton
-class Configuration(object):
+class ConfigurationObject(object):
     """
     NOTE: This class is auto generated by the swagger code generator program.
     Ref: https://github.com/swagger-api/swagger-codegen
@@ -235,3 +224,11 @@ def to_debug_report(self):
                "Version of the API: v1.5.0-snapshot\n"\
                "SDK Package Version: 1.0.0-snapshot".\
                format(env=sys.platform, pyversion=sys.version)
+
+
+configuration = ConfigurationObject()
+
+
+def Configuration():
+    """Simulate a singelton Configuration object for backward compatibility."""
+    return configuration

kubernetes/client/rest.py

@@ -35,7 +35,7 @@
 from six import PY3
 from six.moves.urllib.parse import urlencode
 
-from .configuration import Configuration
+from .configuration import configuration
 
 try:
     import urllib3
@@ -69,31 +69,31 @@ def getheader(self, name, default=None):
 
 class RESTClientObject(object):
 
-    def __init__(self, pools_size=4):
+    def __init__(self, pools_size=4, config=configuration):
         # urllib3.PoolManager will pass all kw parameters to connectionpool
         # https://github.com/shazow/urllib3/blob/f9409436f83aeb79fbaf090181cd81b784f1b8ce/urllib3/poolmanager.py#L75
         # https://github.com/shazow/urllib3/blob/f9409436f83aeb79fbaf090181cd81b784f1b8ce/urllib3/connectionpool.py#L680
         # ca_certs vs cert_file vs key_file
         # http://stackoverflow.com/a/23957365/2985775
 
         # cert_reqs
-        if Configuration().verify_ssl:
+        if config.verify_ssl:
             cert_reqs = ssl.CERT_REQUIRED
         else:
             cert_reqs = ssl.CERT_NONE
 
         # ca_certs
-        if Configuration().ssl_ca_cert:
-            ca_certs = Configuration().ssl_ca_cert
+        if config.ssl_ca_cert:
+            ca_certs = config.ssl_ca_cert
         else:
             # if not set certificate file, use Mozilla's root certificates.
             ca_certs = certifi.where()
 
         # cert_file
-        cert_file = Configuration().cert_file
+        cert_file = config.cert_file
 
         # key file
-        key_file = Configuration().key_file
+        key_file = config.key_file
 
         # https pool manager
         self.pool_manager = urllib3.PoolManager(

kubernetes/config/__init__.py

@@ -14,5 +14,5 @@
 
 from .config_exception import ConfigException
 from .incluster_config import load_incluster_config
-from .kube_config import list_kube_config_contexts
-from .kube_config import load_kube_config
+from .kube_config import (list_kube_config_contexts, load_kube_config,
+                          new_client_from_config)

kubernetes/config/kube_config.py

@@ -19,7 +19,7 @@
 
 import urllib3
 import yaml
-from kubernetes.client import configuration
+from kubernetes.client import ApiClient, ConfigurationObject, configuration
 from oauth2client.client import GoogleCredentials
 
 from .config_exception import ConfigException
@@ -97,7 +97,8 @@ def as_data(self):
 class KubeConfigLoader(object):
 
     def __init__(self, config_dict, active_context=None,
-                 get_google_credentials=None, client_configuration=None,
+                 get_google_credentials=None,
+                 client_configuration=configuration,
                  config_base_path=""):
         self._config = ConfigNode('kube-config', config_dict)
         self._current_context = None
@@ -111,10 +112,7 @@ def __init__(self, config_dict, active_context=None,
             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
+        self._client_configuration = client_configuration
 
     def set_active_context(self, context_name=None):
         if context_name is None:
@@ -279,17 +277,31 @@ def list_kube_config_contexts(config_file=None):
     return loader.list_contexts(), loader.current_context
 
 
-def load_kube_config(config_file=None, context=None):
+def load_kube_config(config_file=None, context=None,
+                     client_configuration=configuration):
     """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.
+        from config file will be used.
+    :param client_configuration: The kubernetes.client.ConfigurationObject to
+        set configs to.
     """
 
     if config_file is None:
         config_file = os.path.expanduser(KUBE_CONFIG_DEFAULT_LOCATION)
 
     _get_kube_config_loader_for_yaml_file(
-        config_file, active_context=context).load_and_set()
+        config_file, active_context=context,
+        client_configuration=client_configuration).load_and_set()
+
+
+def new_client_from_config(config_file=None, context=None):
+    """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)
+    return ApiClient(config=client_config)