Enable providing keystone session for Prometheus

This enables us to create a PrometheusAPIClient, which uses a
keystone session when communicating with Prometheus, which
causes the requests to include an X-Auth-Token header
with the user's keystone token. This will enable observabilityclient
to authenticate when communicating with Aetos in the future.

Change-Id: I3693a6906efccdbb193ddd1e927ed83975592442

observabilityclient/prometheus_client.py

@@ -53,9 +53,12 @@ class PrometheusMetric(object):
 
 
 class PrometheusAPIClient(object):
-    def __init__(self, host):
+    def __init__(self, host, session=None):
         self._host = host
-        self._session = requests.Session()
+        if session is None:
+            self._session = requests.Session()
+        else:
+            self._session = session
         self._session.verify = False
 
     def set_ca_cert(self, ca_cert):
@@ -75,7 +78,8 @@ class PrometheusAPIClient(object):
     def _get(self, endpoint, params=None):
         url = self._get_url(endpoint)
         resp = self._session.get(url, params=params,
-                                 headers={'Accept': 'application/json'})
+                                 headers={'Accept': 'application/json',
+                                          'Accept-Encoding': 'identity'})
         if resp.status_code != requests.codes.ok:
             raise PrometheusAPIClientError(resp)
         decoded = resp.json()

observabilityclient/tests/unit/test_prometheus_client.py

@@ -98,7 +98,8 @@ class PrometheusAPIClientTest(PrometheusAPIClientTestBase):
 
         m.assert_called_with(expected_url,
                              params=expected_params,
-                             headers={'Accept': 'application/json'})
+                             headers={'Accept': 'application/json',
+                                      'Accept-Encoding': 'identity'})
 
     def test_get_error(self):
         url = "test"

observabilityclient/tests/unit/test_utils.py

@@ -55,19 +55,20 @@ class GetPrometheusClientTest(testtools.TestCase):
                 mock.patch.object(prometheus_client.PrometheusAPIClient,
                                   "__init__", return_value=None) as m:
             metric_utils.get_prometheus_client()
-        m.assert_called_with("somehost:1234")
+        m.assert_called_with("somehost:1234", None)
 
-    def test_get_prometheus_client_env_overide(self):
-        with mock.patch.dict(os.environ, {'PROMETHEUS_HOST': 'env_overide'}), \
+    def test_get_prometheus_client_env_override(self):
+        with mock.patch.dict(os.environ,
+                             {'PROMETHEUS_HOST': 'env_override'}), \
                 mock.patch.object(metric_utils, 'get_config_file',
                                   return_value=self.config_file), \
                 mock.patch.object(prometheus_client.PrometheusAPIClient,
                                   "__init__", return_value=None) as m:
             metric_utils.get_prometheus_client()
-        m.assert_called_with("env_overide:1234")
+        m.assert_called_with("env_override:1234", None)
 
     def test_get_prometheus_client_no_config_file(self):
-        patched_env = {'PROMETHEUS_HOST': 'env_overide',
+        patched_env = {'PROMETHEUS_HOST': 'env_override',
                        'PROMETHEUS_PORT': 'env_port'}
         with mock.patch.dict(os.environ, patched_env), \
                 mock.patch.object(metric_utils, 'get_config_file',
@@ -75,7 +76,7 @@ class GetPrometheusClientTest(testtools.TestCase):
                 mock.patch.object(prometheus_client.PrometheusAPIClient,
                                   "__init__", return_value=None) as m:
             metric_utils.get_prometheus_client()
-        m.assert_called_with("env_overide:env_port")
+        m.assert_called_with("env_override:env_port", None)
 
     def test_get_prometheus_client_missing_configuration(self):
         with mock.patch.dict(os.environ, {}), \

observabilityclient/utils/metric_utils.py

@@ -45,7 +45,7 @@ def get_config_file():
     return None
 
 
-def get_prometheus_client():
+def get_prometheus_client(session=None):
     host = None
     port = None
     ca_cert = None
@@ -71,7 +71,7 @@ def get_prometheus_client():
     if host is None or port is None:
         raise ConfigurationError("Can't find prometheus host and "
                                  "port configuration.")
-    client = PrometheusAPIClient(f"{host}:{port}")  # noqa: E231
+    client = PrometheusAPIClient(f"{host}:{port}", session)  # noqa: E231
     if ca_cert is not None:
         client.set_ca_cert(ca_cert)
     return client

observabilityclient/v1/client.py

@@ -38,6 +38,6 @@ class Client(object):
 
         self.session = session
 
-        self.prometheus_client = get_prometheus_client()
+        self.prometheus_client = get_prometheus_client(session)
         self.query = python_api.QueryManager(self)
         self.rbac = rbac.Rbac(self, self.session, disable_rbac)