feat: Implement scope_info_enabled (#3503)

Signed-off-by: Arthur Silva Sens <arthursens2005@gmail.com>
Co-authored-by: Cijo Thomas <cijo.thomas@gmail.com>

Author: ArthurSens

opentelemetry-prometheus/CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## vNext
 
+- Replace `without_scope_info` with `scope_info_enabled` to configure Prometheus instrumentation scope labels, inverting the option from disabling scope info to enabling it. Before this change, the exporter emitted an `otel_scope_info` metric and only added `otel_scope_name`/`otel_scope_version` labels to metric points. Now scope info is enabled by default on metric points with `otel_scope_name`, `otel_scope_version`, `otel_scope_schema_url`, and scope attributes prefixed with `otel_scope_`; setting `scope_info_enabled(false)` suppresses those labels. [#3503](https://github.com/open-telemetry/opentelemetry-rust/pull/3503)
+
 ## 0.32.0
 
 Released 2026-May-08

opentelemetry-prometheus/src/config.rs

@@ -6,18 +6,32 @@ use std::sync::{Arc, Mutex};
 use crate::{Collector, PrometheusExporter, ResourceSelector};
 
 /// [PrometheusExporter] configuration options
-#[derive(Default)]
 pub struct ExporterBuilder {
     registry: Option<prometheus::Registry>,
     disable_target_info: bool,
     without_units: bool,
     without_counter_suffixes: bool,
     namespace: Option<String>,
-    disable_scope_info: bool,
+    scope_info_enabled: bool,
     reader: ManualReaderBuilder,
     resource_selector: ResourceSelector,
 }
 
+impl Default for ExporterBuilder {
+    fn default() -> Self {
+        ExporterBuilder {
+            registry: None,
+            disable_target_info: false,
+            without_units: false,
+            without_counter_suffixes: false,
+            namespace: None,
+            scope_info_enabled: true,
+            reader: ManualReaderBuilder::default(),
+            resource_selector: ResourceSelector::default(),
+        }
+    }
+}
+
 impl fmt::Debug for ExporterBuilder {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_struct("ExporterBuilder")
@@ -26,7 +40,7 @@ impl fmt::Debug for ExporterBuilder {
             .field("without_units", &self.without_units)
             .field("without_counter_suffixes", &self.without_counter_suffixes)
             .field("namespace", &self.namespace)
-            .field("disable_scope_info", &self.disable_scope_info)
+            .field("scope_info_enabled", &self.scope_info_enabled)
             .finish()
     }
 }
@@ -66,20 +80,19 @@ impl ExporterBuilder {
         self
     }
 
-    /// Configures the exporter to not export the `otel_scope_info` metric.
+    /// Configures whether to export instrumentation scope labels on metric points.
     ///
-    /// If not specified, the exporter will create a `otel_scope_info` metric
-    /// containing the metrics' Instrumentation Scope, and also add labels about
-    /// Instrumentation Scope to all metric points.
-    pub fn without_scope_info(mut self) -> Self {
-        self.disable_scope_info = true;
+    /// If not specified, scope info is enabled and the exporter adds
+    /// `otel_scope_*` labels to all metric points.
+    pub fn scope_info_enabled(mut self, enabled: bool) -> Self {
+        self.scope_info_enabled = enabled;
         self
     }
 
     /// Configures the exporter to prefix metrics with the given namespace.
     ///
-    /// Metrics such as `target_info` and `otel_scope_info` are not prefixed since
-    /// these have special behavior based on their name.
+    /// Metrics such as `target_info` are not prefixed since these have special
+    /// behavior based on their name.
     pub fn with_namespace(mut self, namespace: impl Into<String>) -> Self {
         let mut namespace = namespace.into();
 
@@ -123,7 +136,7 @@ impl ExporterBuilder {
             disable_target_info: self.disable_target_info,
             without_units: self.without_units,
             without_counter_suffixes: self.without_counter_suffixes,
-            disable_scope_info: self.disable_scope_info,
+            scope_info_enabled: self.scope_info_enabled,
             create_target_info_once: OnceCell::new(),
             namespace: self.namespace,
             inner: Mutex::new(Default::default()),

opentelemetry-prometheus/src/lib.rs

@@ -65,9 +65,6 @@
 //! // a_histogram_bucket{key="value",otel_scope_name="my-app",le="+Inf"} 1
 //! // a_histogram_sum{key="value",otel_scope_name="my-app"} 100
 //! // a_histogram_count{key="value",otel_scope_name="my-app"} 1
-//! // # HELP otel_scope_info Instrumentation Scope metadata
-//! // # TYPE otel_scope_info gauge
-//! // otel_scope_info{otel_scope_name="my-app"} 1
 //! // # HELP target_info Target metadata
 //! // # TYPE target_info gauge
 //! // target_info{service_name="unknown_service"} 1
@@ -114,10 +111,15 @@ use std::{fmt, sync::Weak};
 const TARGET_INFO_NAME: &str = "target_info";
 const TARGET_INFO_DESCRIPTION: &str = "Target metadata";
 
-const SCOPE_INFO_METRIC_NAME: &str = "otel_scope_info";
-const SCOPE_INFO_DESCRIPTION: &str = "Instrumentation Scope metadata";
-
-const SCOPE_INFO_KEYS: [&str; 2] = ["otel_scope_name", "otel_scope_version"];
+const SCOPE_NAME_LABEL: &str = "otel_scope_name";
+const SCOPE_VERSION_LABEL: &str = "otel_scope_version";
+const SCOPE_SCHEMA_URL_LABEL: &str = "otel_scope_schema_url";
+const SCOPE_ATTRIBUTE_PREFIX: &str = "otel_scope_";
+const RESERVED_SCOPE_LABELS: [&str; 3] = [
+    SCOPE_NAME_LABEL,
+    SCOPE_VERSION_LABEL,
+    SCOPE_SCHEMA_URL_LABEL,
+];
 
 // prometheus counters MUST have a _total suffix by default:
 // https://github.com/open-telemetry/opentelemetry-specification/blob/v1.20.0/specification/compatibility/prometheus_and_openmetrics.md
@@ -170,7 +172,7 @@ struct Collector {
     disable_target_info: bool,
     without_units: bool,
     without_counter_suffixes: bool,
-    disable_scope_info: bool,
+    scope_info_enabled: bool,
     create_target_info_once: OnceCell<MetricFamily>,
     resource_labels_once: OnceCell<Vec<LabelPair>>,
     namespace: Option<String>,
@@ -180,7 +182,6 @@ struct Collector {
 
 #[derive(Default)]
 struct CollectorInner {
-    scope_infos: HashMap<InstrumentationScope, MetricFamily>,
     metric_families: HashMap<String, MetricFamily>,
 }
 
@@ -301,27 +302,8 @@ impl prometheus::core::Collector for Collector {
             .get_or_init(|| self.resource_selector.select(metrics.resource()));
 
         for scope_metrics in metrics.scope_metrics() {
-            let scope_labels = if !self.disable_scope_info {
-                if scope_metrics.scope().attributes().count() > 0 {
-                    let scope_info = inner
-                        .scope_infos
-                        .entry(scope_metrics.scope().clone())
-                        .or_insert_with_key(create_scope_info_metric);
-                    res.push(scope_info.clone());
-                }
-
-                let mut labels =
-                    Vec::with_capacity(1 + scope_metrics.scope().version().is_some() as usize);
-                let mut name = LabelPair::default();
-                name.set_name(SCOPE_INFO_KEYS[0].into());
-                name.set_value(scope_metrics.scope().name().to_string());
-                labels.push(name);
-                if let Some(version) = &scope_metrics.scope().version() {
-                    let mut l_version = LabelPair::default();
-                    l_version.set_name(SCOPE_INFO_KEYS[1].into());
-                    l_version.set_value(version.to_string());
-                    labels.push(l_version);
-                }
+            let scope_labels = if self.scope_info_enabled {
+                let mut labels = get_scope_labels(scope_metrics.scope());
 
                 if !resource_labels.is_empty() {
                     labels.extend(resource_labels.iter().cloned());
@@ -422,6 +404,48 @@ fn get_attrs(kvs: &mut dyn Iterator<Item = (&Key, &Value)>, extra: &[LabelPair])
     res
 }
 
+fn get_scope_labels(scope: &InstrumentationScope) -> Vec<LabelPair> {
+    let mut labels = Vec::with_capacity(
+        1 + scope.version().is_some() as usize
+            + scope.schema_url().is_some() as usize
+            + scope.attributes().count(),
+    );
+    labels.push(label_pair(SCOPE_NAME_LABEL, scope.name()));
+
+    if let Some(version) = scope.version() {
+        labels.push(label_pair(SCOPE_VERSION_LABEL, version));
+    }
+
+    if let Some(schema_url) = scope.schema_url() {
+        labels.push(label_pair(SCOPE_SCHEMA_URL_LABEL, schema_url));
+    }
+
+    let mut attr_labels = BTreeMap::<String, Vec<String>>::new();
+    for kv in scope.attributes() {
+        let label_name = utils::sanitize_prom_kv(&format!("{SCOPE_ATTRIBUTE_PREFIX}{}", kv.key));
+        if RESERVED_SCOPE_LABELS.contains(&label_name.as_str()) {
+            continue;
+        }
+        attr_labels
+            .entry(label_name)
+            .and_modify(|values| values.push(kv.value.to_string()))
+            .or_insert_with(|| vec![kv.value.to_string()]);
+    }
+
+    for (label_name, values) in attr_labels {
+        labels.push(label_pair(label_name, values.join(";")));
+    }
+
+    labels
+}
+
+fn label_pair(name: impl Into<String>, value: impl Into<String>) -> LabelPair {
+    let mut label = LabelPair::default();
+    label.set_name(name.into());
+    label.set_value(value.into());
+    label
+}
+
 fn validate_metrics(
     name: &str,
     description: &str,
@@ -585,34 +609,6 @@ fn create_info_metric(
     mf
 }
 
-fn create_scope_info_metric(scope: &InstrumentationScope) -> MetricFamily {
-    let mut g = prometheus::proto::Gauge::default();
-    g.set_value(1.0);
-
-    let mut labels = Vec::with_capacity(1 + scope.version().is_some() as usize);
-    let mut name = LabelPair::default();
-    name.set_name(SCOPE_INFO_KEYS[0].into());
-    name.set_value(scope.name().to_string());
-    labels.push(name);
-    if let Some(version) = &scope.version() {
-        let mut v_label = LabelPair::default();
-        v_label.set_name(SCOPE_INFO_KEYS[1].into());
-        v_label.set_value(version.to_string());
-        labels.push(v_label);
-    }
-
-    let mut m = prometheus::proto::Metric::default();
-    m.set_label(labels);
-    m.set_gauge(g);
-
-    let mut mf = MetricFamily::default();
-    mf.set_name(SCOPE_INFO_METRIC_NAME.into());
-    mf.set_help(SCOPE_INFO_DESCRIPTION.into());
-    mf.set_field_type(MetricType::GAUGE);
-    mf.set_metric(vec![m]);
-    mf
-}
-
 trait Numeric: fmt::Debug {
     // lossy at large values for u64 and i64 but prometheus only handles floats
     fn as_f64(&self) -> f64;

opentelemetry-prometheus/tests/data/conflict_help_two_counters_1.txt

@@ -1,11 +1,7 @@
 # HELP bar_bytes_total meter a bar
 # TYPE bar_bytes_total counter
-bar_bytes_total{type="bar",otel_scope_name="ma",otel_scope_version="v0.1.0"} 100
-bar_bytes_total{type="bar",otel_scope_name="mb",otel_scope_version="v0.1.0"} 100
-# HELP otel_scope_info Instrumentation Scope metadata
-# TYPE otel_scope_info gauge
-otel_scope_info{otel_scope_name="ma",otel_scope_version="v0.1.0"} 1
-otel_scope_info{otel_scope_name="mb",otel_scope_version="v0.1.0"} 1
+bar_bytes_total{type="bar",otel_scope_name="ma",otel_scope_version="v0.1.0",otel_scope_schema_url="https://opentelemetry.io/schemas/1.0.0",otel_scope_k="v"} 100
+bar_bytes_total{type="bar",otel_scope_name="mb",otel_scope_version="v0.1.0",otel_scope_schema_url="https://opentelemetry.io/schemas/1.0.0",otel_scope_k="v"} 100
 # HELP target_info Target metadata
 # TYPE target_info gauge
 target_info{service_name="prometheus_test",telemetry_sdk_language="rust",telemetry_sdk_name="opentelemetry",telemetry_sdk_version="latest"} 1

opentelemetry-prometheus/tests/data/conflict_help_two_counters_2.txt

@@ -1,11 +1,7 @@
 # HELP bar_bytes_total meter b bar
 # TYPE bar_bytes_total counter
-bar_bytes_total{type="bar",otel_scope_name="ma",otel_scope_version="v0.1.0"} 100
-bar_bytes_total{type="bar",otel_scope_name="mb",otel_scope_version="v0.1.0"} 100
-# HELP otel_scope_info Instrumentation Scope metadata
-# TYPE otel_scope_info gauge
-otel_scope_info{otel_scope_name="ma",otel_scope_version="v0.1.0"} 1
-otel_scope_info{otel_scope_name="mb",otel_scope_version="v0.1.0"} 1
+bar_bytes_total{type="bar",otel_scope_name="ma",otel_scope_version="v0.1.0",otel_scope_schema_url="https://opentelemetry.io/schemas/1.0.0",otel_scope_k="v"} 100
+bar_bytes_total{type="bar",otel_scope_name="mb",otel_scope_version="v0.1.0",otel_scope_schema_url="https://opentelemetry.io/schemas/1.0.0",otel_scope_k="v"} 100
 # HELP target_info Target metadata
 # TYPE target_info gauge
 target_info{service_name="prometheus_test",telemetry_sdk_language="rust",telemetry_sdk_name="opentelemetry",telemetry_sdk_version="latest"} 1