fix: remove space after comma in openmetrics exposition

OpenMetrics doesn't allow for spaces between labels and prometheus fails with a
parsing error.

Removing this fixes UTF8 metrics exposition

Signed-off-by: Dominik Süß <dominik@suess.wtf>

Author: theSuess

prometheus_client/openmetrics/exposition.py

@@ -72,7 +72,7 @@ def generate_latest(registry, escaping=UNDERSCORES, version="1.0.0"):
                 if escaping == ALLOWUTF8 and not _is_valid_legacy_metric_name(s.name):
                     labelstr = escape_metric_name(s.name, escaping)
                     if s.labels:
-                        labelstr += ', '
+                        labelstr += ','
                 else:
                     labelstr = ''
 

tests/openmetrics/test_exposition.py

@@ -169,7 +169,7 @@ def test_native_histogram_utf8_stress(self) -> None:
         self.custom_collector(hfm)
         self.assertEqual(b"""# HELP "native{histogram" Is a basic example of a native histogram
 # TYPE "native{histogram" histogram
-{"native{histogram", "xx{} # {}"=" EOF # {}}}"} {count:24,sum:100,schema:0,zero_threshold:0.001,zero_count:4,negative_spans:[0:2,1:2],negative_deltas:[2,1,-2,3],positive_spans:[0:2,1:2],positive_deltas:[2,1,-3,3]}
+{"native{histogram","xx{} # {}"=" EOF # {}}}"} {count:24,sum:100,schema:0,zero_threshold:0.001,zero_count:4,negative_spans:[0:2,1:2],negative_deltas:[2,1,-2,3],positive_spans:[0:2,1:2],positive_deltas:[2,1,-3,3]}
 # EOF
 """, generate_latest(self.registry, ALLOWUTF8, version="2.0.0"))
 
@@ -189,7 +189,7 @@ def test_native_histogram_with_labels_utf8(self) -> None:
         self.custom_collector(hfm)
         self.assertEqual(b"""# HELP "hist.w.labels" Is a basic example of a native histogram with labels
 # TYPE "hist.w.labels" histogram
-{"hist.w.labels", baz="qux",foo="bar"} {count:24,sum:100,schema:0,zero_threshold:0.001,zero_count:4,negative_spans:[0:2,1:2],negative_deltas:[2,1,-2,3],positive_spans:[0:2,1:2],positive_deltas:[2,1,-3,3]}
+{"hist.w.labels",baz="qux",foo="bar"} {count:24,sum:100,schema:0,zero_threshold:0.001,zero_count:4,negative_spans:[0:2,1:2],negative_deltas:[2,1,-2,3],positive_spans:[0:2,1:2],positive_deltas:[2,1,-3,3]}
 # EOF
 """, generate_latest(self.registry, ALLOWUTF8, version="2.0.0"))