Reject non-string Info keys and values in info()

prometheus_client/metrics.py

@@ -749,6 +749,9 @@ def info(self, val: Dict[str, str]) -> None:
                 self._labelnames, val))
         if any(i is None for i in val.values()):
             raise ValueError('Label value cannot be None')
+        for k, v in val.items():
+            if not isinstance(k, str) or not isinstance(v, str):
+                raise ValueError(f'Info keys and values must be strings, got {k!r}: {v!r}')
         with self._lock:
             self._value = dict(val)
 

tests/test_core.py

@@ -17,6 +17,9 @@
 from prometheus_client.decorator import getargspec
 from prometheus_client.exposition import generate_latest
 from prometheus_client.metrics import _get_use_created
+from prometheus_client.openmetrics.exposition import (
+    generate_latest as openmetrics_generate_latest,
+)
 from prometheus_client.validation import (
     disable_legacy_validation, enable_legacy_validation,
 )
@@ -587,6 +590,17 @@ def test_labels(self):
         self.labels.labels('a').info({'foo': 'bar'})
         self.assertEqual(1, self.registry.get_sample_value('il_info', {'l': 'a', 'foo': 'bar'}))
 
+    def test_non_string_keys_and_values(self):
+        self.info.info({'version': '1.2.3'})
+        for val in ({'version': 1}, {'temperature': 49.0}, {1: 'x'}, {'tags': ['a', 'b']}):
+            with self.subTest(val=val):
+                self.assertRaises(ValueError, self.info.info, val)
+                self.assertRaises(ValueError, self.labels.labels('a').info, val)
+        # The rejected calls keep the previous value and the registry stays scrapeable.
+        self.assertEqual(1, self.registry.get_sample_value('i_info', {'version': '1.2.3'}))
+        self.assertIn(b'i_info{version="1.2.3"} 1.0', generate_latest(self.registry))
+        self.assertIn(b'i_info{version="1.2.3"} 1.0', openmetrics_generate_latest(self.registry))
+
 
 class TestEnum(unittest.TestCase):
     def setUp(self):