Add support to generate metrics as text

README.md

@@ -24,7 +24,7 @@ or paste it into requirements.txt:
 prometheus-flask-exporter
 
 # or with specific version number
-prometheus-flask-exporter==0.20.1
+prometheus-flask-exporter==0.20.2
 ```
 and then install dependencies from requirements.txt file as usual:
 ```
@@ -275,6 +275,22 @@ metrics = PrometheusMetrics(app, metrics_decorator=auth.login_required)
 
 See a full example in the [examples/flask-httpauth](https://github.com/rycus86/prometheus_flask_exporter/tree/master/examples/flask-httpauth) folder.
 
+## Custom metrics endpoint
+
+You can also take full control of the metrics endpoint by generating its contents,
+and managing how it is exposed by yourself.
+
+```python
+app = Flask(__name__)
+# path=None to avoid registering a /metrics endpoint on the same Flask app
+metrics = PrometheusMetrics(app, path=None)
+
+# later ... generate the response (and its content type) to expose to Prometheus
+response_data, content_type = metrics.generate_metrics()
+```
+
+See the related conversation in [issue #135](https://github.com/rycus86/prometheus_flask_exporter/issues/135).
+
 ## Debug mode
 
 Please note, that changes being live-reloaded, when running the Flask

prometheus_flask_exporter/__init__.py

@@ -11,12 +11,13 @@
 from flask import request, make_response, current_app
 from flask.views import MethodViewType
 from prometheus_client import Counter, Histogram, Gauge, Summary
+from prometheus_client import multiprocess as pc_multiprocess, CollectorRegistry
 try:
     # prometheus-client >= 0.14.0
-    from prometheus_client.exposition import choose_formatter
+    from prometheus_client.exposition import choose_encoder
 except ImportError:
     # prometheus-client < 0.14.0
-    from prometheus_client.exposition import choose_encoder as choose_formatter
+    from prometheus_client.exposition import choose_formatter as choose_encoder
 
 from werkzeug.serving import is_running_from_reloader
 
@@ -234,8 +235,8 @@ def init_app(self, app):
         This callback can be used to initialize an application for the
         use with this prometheus reporter setup.
 
-        This is usually used with a Flask "app factory" configuration. Please
-        see: http://flask.pocoo.org/docs/1.0/patterns/appfactories/
+        This is usually used with a Flask "app factory" configuration.
+        Please see: http://flask.pocoo.org/docs/1.0/patterns/appfactories/
 
         Note, that you need to use `PrometheusMetrics.for_app_factory()`
         for this mode, otherwise it is called automatically.
@@ -270,23 +271,15 @@ def register_endpoint(self, path, app=None):
 
         @self.do_not_track()
         def prometheus_metrics():
-            # import these here so they don't clash with our own multiprocess module
-            from prometheus_client import multiprocess, CollectorRegistry
-
-            if 'PROMETHEUS_MULTIPROC_DIR' in os.environ or 'prometheus_multiproc_dir' in os.environ:
-                registry = CollectorRegistry()
-            else:
-                registry = self.registry
-
+            accept_header = request.headers.get("Accept")
             if 'name[]' in request.args:
-                registry = registry.restricted_registry(request.args.getlist('name[]'))
-
-            if 'PROMETHEUS_MULTIPROC_DIR' in os.environ or 'prometheus_multiproc_dir' in os.environ:
-                multiprocess.MultiProcessCollector(registry)
+                names = request.args.getlist('name[]')
+            else:
+                names = None
 
-            generate_latest, content_type = choose_formatter(request.headers.get("Accept"))
+            generated_data, content_type = self.generate_metrics(accept_header, names)
             headers = {'Content-Type': content_type}
-            return generate_latest(registry), 200, headers
+            return generated_data, 200, headers
 
         # apply any user supplied decorators, like authentication
         if self._metrics_decorator:
@@ -295,6 +288,36 @@ def prometheus_metrics():
         # apply the Flask route decorator on our metrics endpoint
         app.route(path)(prometheus_metrics)
 
+    def generate_metrics(self, accept_header=None, names=None):
+        """
+        Generate the metrics output for Prometheus to consume.
+        This can be exposed on a dedicated server, or on the Flask app, or for
+        local development you can use the shorthand method to expose it on a
+        new Flask app, see `PrometheusMetrics.start_http_server()`.
+
+        :param accept_header: The value of the HTTP Accept request header
+            (default `None`)
+        :param names: Names to only return samples for, must be a list of
+            strings if not `None` (default `None`)
+        :return: a tuple of response content and response content type
+            (both `str` types)
+        """
+
+        if 'PROMETHEUS_MULTIPROC_DIR' in os.environ or 'prometheus_multiproc_dir' in os.environ:
+            registry = CollectorRegistry()
+        else:
+            registry = self.registry
+
+        if names:
+            registry = registry.restricted_registry(names)
+
+        if 'PROMETHEUS_MULTIPROC_DIR' in os.environ or 'prometheus_multiproc_dir' in os.environ:
+            pc_multiprocess.MultiProcessCollector(registry)
+
+        generate_latest, content_type = choose_encoder(accept_header)
+        generated_content = generate_latest(registry).decode('utf-8')
+        return generated_content, content_type
+
     def start_http_server(self, port, host='0.0.0.0', endpoint='/metrics', ssl=None):
         """
         Start an HTTP server for exposing the metrics.
@@ -861,9 +884,9 @@ def info(self, name, description, labelnames=None, labelvalues=None, **labels):
     @staticmethod
     def _is_string(value):
         try:
-            return isinstance(value, basestring)  # python2
-        except NameError:
             return isinstance(value, str)  # python3
+        except NameError:
+            return isinstance(value, basestring)  # python2
 
     @staticmethod
     def _not_yet_handled(tracking_key):
@@ -965,4 +988,4 @@ def _make_response(response):
         return _make_response
 
 
-__version__ = '0.20.1'
+__version__ = '0.20.2'

prometheus_flask_exporter/multiprocess.py

@@ -63,7 +63,7 @@ def __init__(self, app=None, **kwargs):
             app=app, path=None, registry=registry, **kwargs
         )
 
-    def start_http_server(self, port, host='0.0.0.0', endpoint=None):
+    def start_http_server(self, port, host='0.0.0.0', endpoint=None, ssl=None):
         """
         Start an HTTP server for exposing the metrics, if the
         `should_start_http_server` function says we should, otherwise just return.
@@ -72,6 +72,7 @@ def start_http_server(self, port, host='0.0.0.0', endpoint=None):
         :param port: the HTTP port to expose the metrics endpoint on
         :param host: the HTTP host to listen on (default: `0.0.0.0`)
         :param endpoint: **ignored**, the HTTP server will respond on any path
+        :param ssl: **ignored**, the server will not support SSL/HTTPS
         """
 
         if self.should_start_http_server():

setup.py

@@ -6,15 +6,15 @@
 setup(
     name='prometheus_flask_exporter',
     packages=['prometheus_flask_exporter'],
-    version='0.20.1',
+    version='0.20.2',
     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/0.20.1.tar.gz',
+    download_url='https://github.com/rycus86/prometheus_flask_exporter/archive/0.20.2.tar.gz',
     keywords=['prometheus', 'flask', 'monitoring', 'exporter'],
     classifiers=[
         'Development Status :: 4 - Beta',

tests/test_endpoint.py

@@ -44,6 +44,42 @@ def test():
         self.assertIn('flask_http_request_duration_seconds_count', str(response.data))
         self.assertIn('flask_http_request_duration_seconds_sum', str(response.data))
 
+    def test_generate_metrics_content(self):
+        metrics = self.metrics(path=None)
+
+        @self.app.route('/test')
+        def test():
+            return 'OK'
+
+        self.client.get('/test')
+
+        response = self.client.get('/metrics')
+        self.assertEqual(404, response.status_code)
+
+        response_data, _ = metrics.generate_metrics()
+
+        self.assertIn('flask_exporter_info', response_data)
+        self.assertIn('flask_http_request_total', response_data)
+        self.assertIn('flask_http_request_duration_seconds', response_data)
+
+        response_data, _ = metrics.generate_metrics(names=['flask_exporter_info'])
+
+        self.assertIn('flask_exporter_info', response_data)
+        self.assertNotIn('flask_http_request_total', response_data)
+        self.assertNotIn('flask_http_request_duration_seconds', response_data)
+
+        response_data, _ = metrics.generate_metrics(names=[
+            'flask_http_request_duration_seconds_bucket',
+            'flask_http_request_duration_seconds_count',
+            'flask_http_request_duration_seconds_sum'
+        ])
+
+        self.assertNotIn('flask_exporter_info', response_data)
+        self.assertNotIn('flask_http_request_total', response_data)
+        self.assertIn('flask_http_request_duration_seconds_bucket', response_data)
+        self.assertIn('flask_http_request_duration_seconds_count', response_data)
+        self.assertIn('flask_http_request_duration_seconds_sum', response_data)
+
     def test_http_server(self):
         metrics = self.metrics()