BugFix: Skip validating and parsing comment lines early (#1108) (#1109)

Signed-off-by: Wissam Abu Ahmad <[email protected]>

Author: wissamir

prometheus_client/parser.py

@@ -308,6 +308,9 @@ def build_metric(name: str, documentation: str, typ: str, samples: List[Sample])
                 continue
             candidate_name, quoted = '', False
             if len(parts) > 2:
+                # Ignore comment tokens
+                if parts[1] != 'TYPE' and parts[1] != 'HELP':
+                    continue
                 candidate_name, quoted = _unquote_unescape(parts[2])
                 if not quoted and not _is_valid_legacy_metric_name(candidate_name):
                     raise ValueError
@@ -342,9 +345,6 @@ def build_metric(name: str, documentation: str, typ: str, samples: List[Sample])
                     'histogram': ['_count', '_sum', '_bucket'],
                 }.get(typ, [''])
                 allowed_names = [name + n for n in allowed_names]
-            else:
-                # Ignore other comment tokens
-                pass
         elif line == '':
             # Ignore blank lines
             pass

tests/test_parser.py

@@ -120,6 +120,17 @@ def test_blank_lines_and_comments(self):
 """)
         self.assertEqualMetrics([CounterMetricFamily("a", "help", value=1)], list(families))
 
+
+    def test_comments_parts_are_not_validated_against_legacy_metric_name(self):
+        # https://github.com/prometheus/client_python/issues/1108
+        families = text_string_to_metric_families("""
+# A simple. comment line where third token cannot be matched against METRIC_NAME_RE under validation.py
+# 3565 12345/4436467 another random comment line where third token cannot be matched against METRIC_NAME_RE under validation.py
+""")
+        self.assertEqualMetrics([], list(families))
+
+
+
     def test_tabs(self):
         families = text_string_to_metric_families("""#\tTYPE\ta\tcounter
 #\tHELP\ta\thelp