Prometheus Exporter string representation for target_info labels

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- Prometheus Exporter string representation for target_info labels
+  ([#3659](https://github.com/open-telemetry/opentelemetry-python/pull/3659))
 - Add Synchronous Gauge instrument
   ([#3462](https://github.com/open-telemetry/opentelemetry-python/pull/3462))
 - Drop support for 3.7

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

@@ -380,7 +380,8 @@ def _create_info_metric(
         """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()
+            self._sanitize(key): self._check_value(value)
+            for key, value in attributes.items()
         }
         info = InfoMetricFamily(name, description, labels=attributes)
         info.add_metric(labels=list(attributes.keys()), value=attributes)

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

@@ -351,30 +351,33 @@ def test_target_info_enabled_by_default(self):
         metric_reader = PrometheusMetricReader()
         provider = MeterProvider(
             metric_readers=[metric_reader],
-            resource=Resource({"os": "Unix", "histo": 1}),
+            resource=Resource({"os": "Unix", "version": "1.2.3"}),
         )
         meter = provider.get_meter("getting-started", "0.1.2")
         counter = meter.create_counter("counter")
         counter.add(1)
         result = list(metric_reader._collector.collect())
 
-        for prometheus_metric in result[: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.assertEqual(prometheus_metric.samples[0].labels["os"], "Unix")
-            self.assertEqual(prometheus_metric.samples[0].labels["histo"], "1")
+        self.assertEqual(len(result), 2)
+
+        prometheus_metric = result[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.assertEqual(prometheus_metric.samples[0].labels["os"], "Unix")
+        self.assertEqual(
+            prometheus_metric.samples[0].labels["version"], "1.2.3"
+        )
 
     def test_target_info_disabled(self):
         metric_reader = PrometheusMetricReader(disable_target_info=True)
         provider = MeterProvider(
             metric_readers=[metric_reader],
-            resource=Resource({"os": "Unix", "histo": 1}),
+            resource=Resource({"os": "Unix", "version": "1.2.3"}),
         )
         meter = provider.get_meter("getting-started", "0.1.2")
         counter = meter.create_counter("counter")
@@ -388,7 +391,7 @@ def test_target_info_disabled(self):
                 prometheus_metric.documentation, "Target metadata"
             )
             self.assertNotIn("os", prometheus_metric.samples[0].labels)
-            self.assertNotIn("histo", prometheus_metric.samples[0].labels)
+            self.assertNotIn("version", prometheus_metric.samples[0].labels)
 
     def test_target_info_sanitize(self):
         metric_reader = PrometheusMetricReader()
@@ -398,6 +401,8 @@ def test_target_info_sanitize(self):
                 {
                     "system.os": "Unix",
                     "system.name": "Prometheus Target Sanitize",
+                    "histo": 1,
+                    "ratio": 0.1,
                 }
             ),
         )
@@ -411,7 +416,7 @@ def test_target_info_sanitize(self):
         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(len(prometheus_metric.samples[0].labels) == 4)
         self.assertTrue("system_os" in prometheus_metric.samples[0].labels)
         self.assertEqual(
             prometheus_metric.samples[0].labels["system_os"], "Unix"
@@ -421,3 +426,13 @@ def test_target_info_sanitize(self):
             prometheus_metric.samples[0].labels["system_name"],
             "Prometheus Target Sanitize",
         )
+        self.assertTrue("histo" in prometheus_metric.samples[0].labels)
+        self.assertEqual(
+            prometheus_metric.samples[0].labels["histo"],
+            "1",
+        )
+        self.assertTrue("ratio" in prometheus_metric.samples[0].labels)
+        self.assertEqual(
+            prometheus_metric.samples[0].labels["ratio"],
+            "0.1",
+        )