Allow exporting default request latencies as summary instead of histo…

…gram

README.md

@@ -73,6 +73,7 @@ The following metrics are exported by default
 
 The prefix for the default metrics can be controlled by the `defaults_prefix` parameter.
 If you don't want to use any prefix, pass the `prometheus_flask_exporter.NO_PREFIX` value in.
+The buckets on the default request latency histogram can be changed by the `buckets` parameter, and if using a summary for them is more appropriate for your use case, then use the `default_latency_as_histogram=False` parameter.
 
 To register your own *default* metrics that will track all registered
 Flask view functions, use the `register_default` function.

prometheus_flask_exporter/__init__.py

@@ -105,6 +105,7 @@ def echo_status(status):
     def __init__(self, app, path='/metrics',
                  export_defaults=True, defaults_prefix='flask',
                  group_by='path', buckets=None,
+                 default_latency_as_histogram=True,
                  default_labels=None, response_converter=None,
                  excluded_paths=None, registry=None, **kwargs):
         """
@@ -123,6 +124,8 @@ def __init__(self, app, path='/metrics',
             (defaults to `path`)
         :param buckets: the time buckets for request latencies
             (will use the default when `None`)
+        :param default_latency_as_histogram: export request latencies
+            as a Histogram (defaults), otherwise use a Summary
         :param default_labels: default labels to attach to each of the
             metrics exposed by this `PrometheusMetrics` instance
         :param response_converter: a function that converts the captured
@@ -137,6 +140,7 @@ def __init__(self, app, path='/metrics',
         self._export_defaults = export_defaults
         self._defaults_prefix = defaults_prefix or 'flask'
         self._default_labels = default_labels or {}
+        self._default_latency_as_histogram = default_latency_as_histogram
         self._response_converter = response_converter or make_response
         self.buckets = buckets
         self.version = __version__
@@ -224,8 +228,9 @@ def init_app(self, app):
 
         if self._export_defaults:
             self.export_defaults(
-                self.buckets, self.group_by,
-                self._defaults_prefix, app
+                buckets=self.buckets, group_by=self.group_by,
+                latency_as_histogram=self._default_latency_as_histogram,
+                prefix=self._defaults_prefix, app=app
             )
 
     def register_endpoint(self, path, app=None):
@@ -289,6 +294,7 @@ def run_app():
         thread.start()
 
     def export_defaults(self, buckets=None, group_by='path',
+                        latency_as_histogram=True,
                         prefix='flask', app=None, **kwargs):
         """
         Export the default metrics:
@@ -301,6 +307,9 @@ def export_defaults(self, buckets=None, group_by='path',
         :param group_by: group default HTTP metrics by
             this request property, like `path`, `endpoint`, `rule`, etc.
             (defaults to `path`)
+        :param latency_as_histogram: export request latencies
+            as a Histogram, otherwise use a Summary instead
+            (defaults to `True` to export as a Histogram)
         :param prefix: prefix to start the default metrics names with
             or `NO_PREFIX` (to skip prefix)
         :param app: the Flask application
@@ -312,11 +321,6 @@ def export_defaults(self, buckets=None, group_by='path',
         if not prefix:
             prefix = self._defaults_prefix or 'flask'
 
-        # use the default buckets from prometheus_client if not given here
-        buckets_as_kwargs = {}
-        if buckets is not None:
-            buckets_as_kwargs['buckets'] = buckets
-
         if kwargs.get('group_by_endpoint') is True:
             warnings.warn(
                 'The `group_by_endpoint` argument of '
@@ -354,13 +358,28 @@ def export_defaults(self, buckets=None, group_by='path',
 
         labels = self._get_combined_labels(None)
 
-        request_duration_metric = Histogram(
-            '%shttp_request_duration_seconds' % prefix,
-            'Flask HTTP request duration in seconds',
-            ('method', duration_group_name, 'status') + labels.keys(),
-            registry=self.registry,
-            **buckets_as_kwargs
-        )
+        if latency_as_histogram:
+            # use the default buckets from prometheus_client if not given here
+            buckets_as_kwargs = {}
+            if buckets is not None:
+                buckets_as_kwargs['buckets'] = buckets
+
+            request_duration_metric = Histogram(
+                '%shttp_request_duration_seconds' % prefix,
+                'Flask HTTP request duration in seconds',
+                ('method', duration_group_name, 'status') + labels.keys(),
+                registry=self.registry,
+                **buckets_as_kwargs
+            )
+
+        else:
+            # export as Summary instead
+            request_duration_metric = Summary(
+                '%shttp_request_duration_seconds' % prefix,
+                'Flask HTTP request duration in seconds',
+                ('method', duration_group_name, 'status') + labels.keys(),
+                registry=self.registry
+            )
 
         counter_labels = ('method', 'status') + labels.keys()
         request_total_metric = Counter(
@@ -884,4 +903,4 @@ def _make_response(response):
         return _make_response
 
 
-__version__ = '0.15.4'
+__version__ = '0.16.0'

setup.py

@@ -6,15 +6,15 @@
 setup(
     name='prometheus_flask_exporter',
     packages=['prometheus_flask_exporter'],
-    version='0.15.4',
+    version='0.16.0',
     description='Prometheus metrics exporter for Flask',
     long_description=long_description,
     long_description_content_type='text/markdown',
     license='MIT',
     author='Viktor Adam',
     author_email='rycus86@gmail.com',
     url='https://github.com/rycus86/prometheus_flask_exporter',
-    download_url='https://github.com/rycus86/prometheus_flask_exporter/archive/0.15.4.tar.gz',
+    download_url='https://github.com/rycus86/prometheus_flask_exporter/archive/0.16.0.tar.gz',
     keywords=['prometheus', 'flask', 'monitoring', 'exporter'],
     classifiers=[
         'Development Status :: 4 - Beta',

tests/test_defaults.py

@@ -385,6 +385,48 @@ def test():
             ('method', 'GET'), ('path', '/test'),
         )
 
+    def test_export_latencies_as_summary(self):
+        metrics = self.metrics(export_defaults=False)
+
+        @self.app.route('/test')
+        def test():
+            return 'OK'
+
+        self.client.get('/test')
+        self.client.get('/test')
+
+        self.assertAbsent(
+            'flask_http_request_duration_seconds_sum',
+            ('method', 'GET'), ('path', '/test'), ('status', 200)
+        )
+        self.assertAbsent(
+            'flask_http_request_duration_seconds_count',
+            ('method', 'GET'), ('path', '/test'), ('status', 200)
+        )
+        self.assertAbsent(
+            'flask_http_request_duration_seconds_bucket',
+            ('le', '+Inf'), ('method', 'GET'), ('path', '/test'), ('status', 200)
+        )
+
+        metrics.export_defaults(latency_as_histogram=False)
+
+        self.client.get('/test')
+        self.client.get('/test')
+        self.client.get('/test')
+
+        self.assertMetric(
+            'flask_http_request_duration_seconds_sum', '[0-9.e-]+',
+            ('method', 'GET'), ('path', '/test'), ('status', 200)
+        )
+        self.assertMetric(
+            'flask_http_request_duration_seconds_count', '3.0',
+            ('method', 'GET'), ('path', '/test'), ('status', 200)
+        )
+        self.assertAbsent(
+            'flask_http_request_duration_seconds_bucket',
+            ('le', '+Inf'), ('method', 'GET'), ('path', '/test'), ('status', 200)
+        )
+
     def test_non_automatic_endpoint_registration(self):
         metrics = self.metrics(path=None)
 
@@ -407,6 +449,25 @@ def test():
             endpoint='/manual/metrics'
         )
 
+    def test_latencies_as_summary(self):
+        self.metrics(default_latency_as_histogram=False)
+
+        @self.app.route('/test')
+        def test():
+            return 'OK'
+
+        self.client.get('/test')
+        self.client.get('/test')
+
+        self.assertMetric(
+            'flask_http_request_duration_seconds_sum', '[0-9.e-]+',
+            ('method', 'GET'), ('path', '/test'), ('status', 200)
+        )
+        self.assertMetric(
+            'flask_http_request_duration_seconds_count', '2.0',
+            ('method', 'GET'), ('path', '/test'), ('status', 200)
+        )
+
     def test_custom_buckets(self):
         self.metrics(buckets=(0.2, 2, 4))
 

tests/test_group_by.py

@@ -29,6 +29,29 @@ def a_test_endpoint(url):
                 endpoint='/metrics'
             )
 
+    def test_group_by_path_default_with_summaries(self):
+        self.metrics(default_latency_as_histogram=False)
+
+        @self.app.route('/<url>')
+        def a_test_endpoint(url):
+            return url + ' is OK'
+
+        self.client.get('/default1')
+        self.client.get('/default2')
+        self.client.get('/default3')
+
+        for path in ('/default1', '/default2', '/default3'):
+            self.assertMetric(
+                'flask_http_request_duration_seconds_sum', '[0-9.e-]+',
+                ('path', path), ('status', 200), ('method', 'GET'),
+                endpoint='/metrics'
+            )
+            self.assertMetric(
+                'flask_http_request_duration_seconds_count', '1.0',
+                ('path', path), ('status', 200), ('method', 'GET'),
+                endpoint='/metrics'
+            )
+
     def test_group_by_path(self):
         self.metrics(group_by='path')