Fix spaces in grouping key values for push_to_gateway

Use base64 encoding for grouping key values containing spaces,
similar to how values with slashes are handled. This prevents
spaces from being converted to '+' signs by quote_plus().

Fixes #1064

Signed-off-by: Varun Chawla <varun_6april@hotmail.com>

Author: veeceey

prometheus_client/exposition.py

@@ -783,8 +783,9 @@ def _escape_grouping_key(k, v):
     if v == "":
         # Per https://github.com/prometheus/pushgateway/pull/346.
         return k + "@base64", "="
-    elif '/' in v:
+    elif '/' in v or ' ' in v:
         # Added in Pushgateway 0.9.0.
+        # Use base64 encoding for values containing slashes or spaces
         return k + "@base64", base64.urlsafe_b64encode(v.encode("utf-8")).decode("utf-8")
     else:
         return k, quote_plus(v)

tests/test_exposition.py

@@ -301,6 +301,13 @@ def test_push_with_groupingkey_empty_label(self):
         self.assertEqual(self.requests[0][0].headers.get('content-type'), CONTENT_TYPE_PLAIN_0_0_4)
         self.assertEqual(self.requests[0][1], b'# HELP g help\n# TYPE g gauge\ng 0.0\n')
 
+    def test_push_with_groupingkey_with_spaces(self):
+        push_to_gateway(self.address, "my_job", self.registry, {'label': 'value with spaces'})
+        self.assertEqual(self.requests[0][0].command, 'PUT')
+        self.assertEqual(self.requests[0][0].path, '/metrics/job/my_job/label@base64/dmFsdWUgd2l0aCBzcGFjZXM=')
+        self.assertEqual(self.requests[0][0].headers.get('content-type'), CONTENT_TYPE_PLAIN_0_0_4)
+        self.assertEqual(self.requests[0][1], b'# HELP g help\n# TYPE g gauge\ng 0.0\n')
+
     def test_push_with_complex_groupingkey(self):
         push_to_gateway(self.address, "my_job", self.registry, {'a': 9, 'b': 'a/ z'})
         self.assertEqual(self.requests[0][0].command, 'PUT')