Add tags support to GraphiteBridge

Graphite has support for tagged metrics with a syntax very similar to
the non-tagged format.  Update GraphiteBridge to support it.

Signed-off-by: Matt Wilder <me@partcyb.org>

README.md

@@ -440,13 +440,24 @@ Metrics are pushed over TCP in the Graphite plaintext format.
 ```python
 from prometheus_client.bridge.graphite import GraphiteBridge
 
-gb = GraphiteBridge(('graphite.your.org', 2003))
+gb = GraphiteBridge('graphite.your.org', 2003)
 # Push once.
 gb.push()
 # Push every 10 seconds in a daemon thread.
 gb.start(10.0)
 ```
 
+Graphite [tags](https://grafana.com/blog/2018/01/11/graphite-1.1-teaching-an-old-dog-new-tricks/) are also supported.
+
+```python
+from prometheus_client.bridge.graphite import GraphiteBridge
+
+gb = GraphiteBridge('graphite.your.org', 2003, tags=True)
+c = Counter('my_requests_total', 'HTTP Failures', ['method', 'endpoint'])
+c.labels('get', '/').inc()
+gb.push()
+```
+
 ## Custom Collectors
 
 Sometimes it is not possible to directly instrument code, as it is not

prometheus_client/bridge/graphite.py

@@ -46,9 +46,10 @@ def run(self):
 
 
 class GraphiteBridge(object):
-    def __init__(self, address, registry=REGISTRY, timeout_seconds=30, _timer=time.time):
+    def __init__(self, address, registry=REGISTRY, tags=False, timeout_seconds=30, _timer=time.time):
         self._address = address
         self._registry = registry
+        self._tags = tags
         self._timeout = timeout_seconds
         self._timer = _timer
 
@@ -63,8 +64,14 @@ def push(self, prefix=''):
         for metric in self._registry.collect():
             for s in metric.samples:
                 if s.labels:
-                    labelstr = '.' + '.'.join(
-                        ['{0}.{1}'.format(
+                    if self._tags:
+                        sep = ';'
+                        fmt = '{0}={1}'
+                    else:
+                        sep = '.'
+                        fmt = '{0}.{1}'
+                    labelstr = sep + sep.join(
+                        [fmt.format(
                             _sanitize(k), _sanitize(v))
                             for k, v in sorted(s.labels.items())])
                 else:

tests/test_graphite_bridge.py

@@ -35,8 +35,11 @@ def run(self):
         self.t.start()
 
         # Explicitly use localhost as the target host, since connecting to 0.0.0.0 fails on Windows
-        address = ('localhost', server.server_address[1])
-        self.gb = GraphiteBridge(address, self.registry, _timer=fake_timer)
+        self.address = ('localhost', server.server_address[1])
+        self.gb = GraphiteBridge(self.address, self.registry, _timer=fake_timer)
+
+    def _use_tags(self):
+        self.gb = GraphiteBridge(self.address, self.registry, tags=True, _timer=fake_timer)
 
     def test_nolabels(self):
         gauge = Gauge('g', 'help', registry=self.registry)
@@ -56,6 +59,16 @@ def test_labels(self):
 
         self.assertEqual(b'labels.a.c.b.d 1.0 1434898897\n', self.data)
 
+    def test_labels_tags(self):
+        self._use_tags()
+        labels = Gauge('labels', 'help', ['a', 'b'], registry=self.registry)
+        labels.labels('c', 'd').inc()
+
+        self.gb.push()
+        self.t.join()
+
+        self.assertEqual(b'labels;a=c;b=d 1.0 1434898897\n', self.data)
+
     def test_prefix(self):
         labels = Gauge('labels', 'help', ['a', 'b'], registry=self.registry)
         labels.labels('c', 'd').inc()
@@ -65,6 +78,16 @@ def test_prefix(self):
 
         self.assertEqual(b'pre.fix.labels.a.c.b.d 1.0 1434898897\n', self.data)
 
+    def test_prefix_tags(self):
+        self._use_tags()
+        labels = Gauge('labels', 'help', ['a', 'b'], registry=self.registry)
+        labels.labels('c', 'd').inc()
+
+        self.gb.push(prefix='pre.fix')
+        self.t.join()
+
+        self.assertEqual(b'pre.fix.labels;a=c;b=d 1.0 1434898897\n', self.data)
+
     def test_sanitizing(self):
         labels = Gauge('labels', 'help', ['a'], registry=self.registry)
         labels.labels('c.:8').inc()
@@ -73,3 +96,13 @@ def test_sanitizing(self):
         self.t.join()
 
         self.assertEqual(b'labels.a.c__8 1.0 1434898897\n', self.data)
+
+    def test_sanitizing_tags(self):
+        self._use_tags()
+        labels = Gauge('labels', 'help', ['a'], registry=self.registry)
+        labels.labels('c.:8').inc()
+
+        self.gb.push()
+        self.t.join()
+
+        self.assertEqual(b'labels;a=c__8 1.0 1434898897\n', self.data)