Prometheus exporter sanitize info metric (#3572)

* Prometheus Exporter sanitize info metric

* Update CHANGELOG.md

* Test Prometheus exporter target info sanitize

* Prometheus exporter paint it black

---------

Co-authored-by: Diego Hurtado <[email protected]>

Author: kornerc

CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- Prometheus exporter sanitize info metric ([#3572](https://github.com/open-telemetry/opentelemetry-python/pull/3572))
 - Remove Jaeger exporters
   ([#3554](https://github.com/open-telemetry/opentelemetry-python/pull/3554))
 - Log stacktrace on `UNKNOWN` status OTLP export error 

exporter/opentelemetry-exporter-prometheus/src/opentelemetry/exporter/prometheus/__init__.py

@@ -378,6 +378,10 @@ def _create_info_metric(
         self, name: str, description: str, attributes: Dict[str, str]
     ) -> InfoMetricFamily:
         """Create an Info Metric Family with list of attributes"""
+        # sanitize the attribute names according to Prometheus rule
+        attributes = {
+            self._sanitize(key): value for key, value in attributes.items()
+        }
         info = InfoMetricFamily(name, description, labels=attributes)
         info.add_metric(labels=list(attributes.keys()), value=attributes)
         return info

exporter/opentelemetry-exporter-prometheus/tests/test_prometheus_exporter.py

@@ -389,3 +389,35 @@ def test_target_info_disabled(self):
             )
             self.assertNotIn("os", prometheus_metric.samples[0].labels)
             self.assertNotIn("histo", prometheus_metric.samples[0].labels)
+
+    def test_target_info_sanitize(self):
+        metric_reader = PrometheusMetricReader()
+        provider = MeterProvider(
+            metric_readers=[metric_reader],
+            resource=Resource(
+                {
+                    "system.os": "Unix",
+                    "system.name": "Prometheus Target Sanitize",
+                }
+            ),
+        )
+        meter = provider.get_meter("getting-started", "0.1.2")
+        counter = meter.create_counter("counter")
+        counter.add(1)
+        prometheus_metric = list(metric_reader._collector.collect())[0]
+
+        self.assertEqual(type(prometheus_metric), InfoMetricFamily)
+        self.assertEqual(prometheus_metric.name, "target")
+        self.assertEqual(prometheus_metric.documentation, "Target metadata")
+        self.assertTrue(len(prometheus_metric.samples) == 1)
+        self.assertEqual(prometheus_metric.samples[0].value, 1)
+        self.assertTrue(len(prometheus_metric.samples[0].labels) == 2)
+        self.assertTrue("system_os" in prometheus_metric.samples[0].labels)
+        self.assertEqual(
+            prometheus_metric.samples[0].labels["system_os"], "Unix"
+        )
+        self.assertTrue("system_name" in prometheus_metric.samples[0].labels)
+        self.assertEqual(
+            prometheus_metric.samples[0].labels["system_name"],
+            "Prometheus Target Sanitize",
+        )