Prevent scrape failures for months w/o usage details (fixes #9) (#10)

* add failing tests for an "empty" month
* special treatment for "empty" moths
* adapted changelog accordingly
* moved the API output for an empty month to the sample_data file

CHANGELOG.md

@@ -4,6 +4,12 @@ Change Log
 All notable changes to this project are noted in this file. This project adheres to [Semantic
 Versioning](http://semver.org/).
 
+0.3.1
+-----
+
+- Fixed the exporter to cope with the non-standard response for months
+  without usage details.
+
 
 0.3.0
 -----

azure_costs_exporter/prometheus_collector.py

@@ -68,6 +68,10 @@ def _get_azure_data(self, month=None):
         rsp = requests.get(url, headers=headers, timeout=10)
         rsp.raise_for_status()
 
+        if rsp.text.startswith('"Usage Data Extract"'):
+            # special treatement for no usage details. Azure API doesn't return a JSON document in that case...
+            return dict()
+
         return rsp.json()
 
     def _create_counter(self):

tests/data.py

@@ -1,3 +1,7 @@
+api_output_for_empty_months = """"Usage Data Extract",
+    "",
+    "AccountOwnerId","Account Name","ServiceAdministratorId","SubscriptionId","SubscriptionGuid","Subscription Name","Date","Month","Day","Year","Product","Meter ID","Meter Category","Meter Sub-Category","Meter Region","Meter Name","Consumed Quantity","ResourceRate","ExtendedCost","Resource Location","Consumed Service","Instance ID","ServiceInfo1","ServiceInfo2","AdditionalInfo","Tags","Store Service Identifier","Department Name","Cost Center","Unit Of Measure","Resource Group",'
+    """
 sample_data = [{u'AccountName': u'Platform',
   u'AccountOwnerId': u'donald.duck',
   u'AdditionalInfo': u'',

tests/test_app.py

@@ -3,7 +3,7 @@
 import datetime
 
 from azure_costs_exporter.main import create_app
-from .data import sample_data
+from .data import sample_data, api_output_for_empty_months
 
 
 @pytest.fixture
@@ -61,6 +61,24 @@ def test_metrics(app, now, enrollment):
     assert rsp.data.count(b'azure_costs_eur') == 4
 
 
+@responses.activate
+def test_metrics_no_usage(app, now, enrollment):
+
+
+    responses.add(
+        method='GET',
+        url="https://ea.azure.com/rest/{0}/usage-report?month={1}&type=detail&fmt=Json".format(enrollment, now),
+        match_querystring=True,
+        body=api_output_for_empty_months
+    )
+
+    rsp = app.test_client().get('/metrics')
+    assert rsp.status_code == 200
+
+    # expect only metric definition and help but no content in the output
+    assert rsp.data.count(b'azure_costs_eur') == 2
+
+
 @responses.activate
 def test_failing_target(client, now):
     responses.add(

tests/test_collector.py

@@ -5,7 +5,7 @@
 from azure_costs_exporter.prometheus_collector import convert_json_df, AzureEABillingCollector
 from azure_costs_exporter.prometheus_collector import base_columns, cost_column
 
-from .data import sample_data
+from .data import sample_data, api_output_for_empty_months
 
 
 def current_month():
@@ -59,15 +59,40 @@ def test_extract_metrics():
 @responses.activate
 def test_get_azure_data():
 
-    enrollment='12345'
+    enrollment = '123'
+    base_url = "https://ea.azure.com/rest/{}/usage-report".format(enrollment)
+    params = "?month={}&type=detail&fmt=Json".format(current_month())
+
     c = AzureEABillingCollector('cloud_costs', enrollment, 'abc123xyz')
 
     responses.add(
         method='GET',
-        url="https://ea.azure.com/rest/{}/usage-report?month=2017-03&type=detail&fmt=Json".format(enrollment),
+        url=base_url+params,
         match_querystring=True,
         json=sample_data
     )
 
-    data = c._get_azure_data('2017-03')
+    data = c._get_azure_data(current_month())
     assert data == sample_data
+
+
+@responses.activate
+def test_empty_month():
+    """
+    If no usage details have are available for a given month the API does not return a JSON document.    
+    """
+    enrollment = '123'
+    base_url = "https://ea.azure.com/rest/{}/usage-report".format(enrollment)
+    params = "?month={}&type=detail&fmt=Json".format(current_month())
+
+    c = AzureEABillingCollector('cloud_costs', enrollment, 'abc123xyz')
+
+    responses.add(
+        method='GET',
+        url=base_url+params,
+        match_querystring=True,
+        body=api_output_for_empty_months
+    )
+
+    data = c._get_azure_data(current_month())
+    assert data == dict()