Add PrometheusMetricsFactory (#142)

* Add PrometheusMetricsFactory

Signed-off-by: Eundoo Song <[email protected]>

Author: eundoosong

README.md

@@ -81,6 +81,23 @@ def init_jaeger_tracer(service_name='your-app-name'):
 
 Note that the call `initialize_tracer()` also sets the `opentracing.tracer` global variable.
 
+#### Prometheus metrics
+
+This module brings a [Prometheus](https://github.com/prometheus/client_python) integration to the internal Jaeger metrics.  
+The way to initialize the tracer with Prometheus metrics:
+
+```python
+from jaeger_client.metrics.prometheus import PrometheusMetricsFactory
+
+config = Config(
+        config={},
+        service_name='your-app-name',
+        validate=True,
+        metrics_factory=PrometheusMetricsFactory(namespace='your-app-name')
+)
+tracer = config.initialize_tracer()
+```
+
 ### Development
 
 For development, some parameters can be passed via `config` dictionary, as in the Getting Started example above. For more details please see the [Config class](jaeger_client/config.py).
@@ -138,7 +155,6 @@ The B3 codec assumes it will receive lowercase HTTP headers, as this seems
 to be the standard in the popular frameworks like Flask and Django.
 Please make sure your framework does the same.
 
-
 ## License
 
 [Apache 2.0 License](./LICENSE).

jaeger_client/metrics/prometheus.py

@@ -0,0 +1,61 @@
+# Copyright (c) 2018, The Jaeger Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from jaeger_client.metrics import MetricsFactory
+from collections import defaultdict
+from prometheus_client import Counter, Gauge
+
+
+class PrometheusMetricsFactory(MetricsFactory):
+    """
+    Provides metrics backed by Prometheus
+    """
+    def __init__(self, namespace=''):
+        self._cache = defaultdict(object)
+        self._namespace = namespace
+
+    def _get_tag_name_list(self, tags):
+        if tags is None:
+            return []
+        tag_name_list = []
+        for key in tags.keys():
+            tag_name_list.append(key)
+        return tag_name_list
+
+    def _get_metric(self, metric, name, label_name_list):
+        cache_key = name + ''.join(label_name_list)
+        if self._cache.get(cache_key) is None:
+            self._cache[cache_key] = metric(name=name, documentation=name,
+                                            labelnames=label_name_list, namespace=self._namespace)
+        return self._cache[cache_key]
+
+    def create_counter(self, name, tags=None):
+        label_name_list = self._get_tag_name_list(tags)
+        counter = self._get_metric(Counter, name, label_name_list)
+        if tags is not None and len(tags) > 0:
+            counter = counter.labels(**tags)
+
+        def increment(value):
+            counter.inc(value)
+        return increment
+
+    def create_gauge(self, name, tags=None):
+        label_name_list = self._get_tag_name_list(tags)
+        gauge = self._get_metric(Gauge, name, label_name_list)
+        if tags is not None and len(tags) > 0:
+            gauge = gauge.labels(**tags)
+
+        def update(value):
+            gauge.set(value)
+        return update

setup.py

@@ -62,6 +62,7 @@
             'coveralls',
             'tchannel>=0.27;python_version<"3"',
             'opentracing_instrumentation>=2,<3',
+            'prometheus_client',
         ]
     },
 )

tests/test_prometheus.py

@@ -0,0 +1,48 @@
+# Copyright (c) 2018, The Jaeger Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from jaeger_client.metrics.prometheus \
+    import PrometheusMetricsFactory
+from prometheus_client import REGISTRY
+
+
+def test_prometheus_metrics_counter():
+    metrics = PrometheusMetricsFactory(namespace='test')
+    counter1 = metrics.create_counter(name='jaeger:test_counter', tags={'result': 'ok'})
+    counter1(1)
+    counter2 = metrics.create_counter(name='jaeger:test_counter', tags={'result': 'ok'})
+    counter2(1)
+    after = REGISTRY.get_sample_value('test_jaeger:test_counter', {'result': 'ok'})
+    assert 2 == after
+
+def test_prometheus_metrics_counter_without_tags():
+    metrics = PrometheusMetricsFactory()
+    counter = metrics.create_counter(name='jaeger:test_counter_no_tags')
+    counter(1)
+    after = REGISTRY.get_sample_value('jaeger:test_counter_no_tags')
+    assert 1 == after
+
+def test_prometheus_metrics_guage():
+    metrics = PrometheusMetricsFactory(namespace='test')
+    gauge = metrics.create_gauge(name='jaeger:test_gauge', tags={'result': 'ok'})
+    gauge(1)
+    after = REGISTRY.get_sample_value('test_jaeger:test_gauge', {'result': 'ok'})
+    assert 1 == after
+
+def test_prometheus_metrics_gauge_without_tags():
+    metrics = PrometheusMetricsFactory()
+    gauge = metrics.create_gauge(name='jaeger:test_gauge_no_tags')
+    gauge(1)
+    after = REGISTRY.get_sample_value('jaeger:test_gauge_no_tags')
+    assert 1 == after