Fix handling 204 No Content responses from Grafana HTTP API

Those kinds of responses are yielded, for example, when deleting alert
provisioning rules.

Author: amotl

grafana_client/client.py

@@ -158,6 +158,12 @@ def __request_runner(url, json=None, data=None, headers=None):
                         response,
                         "Client Error {0}: {1}".format(r.status_code, message),
                     )
+
+            # `204 No Content` responses have an empty response body,
+            # so it doesn't decode well from JSON.
+            if r.status_code == 204:
+                return None
+
             # The "Tempo" data source responds with text/plain.
             if r.headers.get("Content-Type", "").startswith("text/"):
                 return r.text

test/test_grafana_client.py

@@ -13,10 +13,10 @@
 
 
 class MockResponse:
-    def __init__(self, json_data, status_code, headers=None):
-        self.json_data = json_data
+    def __init__(self, status_code, headers=None, json_data=None):
         self.status_code = status_code
         self.headers = headers or {"Content-Type": "application/json"}
+        self.json_data = json_data
 
     def json(self):
         return self.json_data
@@ -63,15 +63,15 @@ def test_grafana_client_no_verify(self):
         )
         grafana.client.s.get = Mock(name="get")
         grafana.client.s.get.return_value = MockResponse(
-            {
+            status_code=200,
+            json_data={
                 "email": "[email protected]",
                 "name": "admin",
                 "login": "admin",
                 "theme": "light",
                 "orgId": 1,
                 "isGrafanaAdmin": True,
             },
-            200,
         )
 
         basic_auth = requests.auth.HTTPBasicAuth("admin", "admin")
@@ -147,3 +147,12 @@ def test_grafana_client_version(self, mock_get):
     def test_grafana_client_non_json_response(self):
         grafana = GrafanaApi.from_url("https://httpbin.org/html")
         self.assertRaises(GrafanaClientError, lambda: grafana.connect())
+
+    def test_grafana_client_204_no_content_response(self):
+        grafana = GrafanaApi.from_url()
+        grafana.client.s.delete = Mock(name="get")
+        grafana.client.s.delete.return_value = MockResponse(
+            status_code=204,
+        )
+        response = grafana.alertingprovisioning.delete_alertrule("foobar")
+        assert response is None