feat(common): add schema_url to resource.

opentelemetry-otlp/src/transform/metrics.rs

@@ -14,6 +14,7 @@ pub(crate) mod tonic {
         ArrayAggregator, HistogramAggregator, LastValueAggregator, MinMaxSumCountAggregator,
         SumAggregator,
     };
+    use opentelemetry::sdk::InstrumentationLibrary;
     use opentelemetry_proto::tonic::metrics::v1::DataPointFlags;
     use opentelemetry_proto::tonic::FromNumber;
     use opentelemetry_proto::tonic::{
@@ -28,7 +29,6 @@ pub(crate) mod tonic {
 
     use crate::to_nanos;
     use crate::transform::{CheckpointedMetrics, ResourceWrapper};
-    use opentelemetry::sdk::InstrumentationLibrary;
     use std::collections::{BTreeMap, HashMap};
 
     pub(crate) fn record_to_metric(
@@ -212,14 +212,21 @@ pub(crate) mod tonic {
             resource_metrics: sink_map
                 .into_iter()
                 .map(|(resource, metric_map)| ResourceMetrics {
+                    schema_url: resource
+                        .schema_url()
+                        .map(|s| s.to_string())
+                        .unwrap_or_default(),
                     resource: Some(resource.into()),
-                    schema_url: "".to_string(), // todo: replace with actual schema url.
                     instrumentation_library_metrics: metric_map
                         .into_iter()
                         .map(
                             |(instrumentation_library, metrics)| InstrumentationLibraryMetrics {
+                                schema_url: instrumentation_library
+                                    .schema_url
+                                    .clone()
+                                    .unwrap_or_default()
+                                    .to_string(),
                                 instrumentation_library: Some(instrumentation_library.into()),
-                                schema_url: "".to_string(), // todo: replace with actual schema url.
                                 metrics: metrics
                                     .into_iter()
                                     .map(|(_k, v)| v)
@@ -385,7 +392,7 @@ mod tests {
                             version: instrumentation_version.unwrap_or("").to_string(),
                         },
                     ),
-                    schema_url: "".to_string(), // todo: replace with actual schema url.
+                    schema_url: "".to_string(),
                     metrics: metrics
                         .into_iter()
                         .map(|(name, data_points)| get_metric_with_name(name, data_points))
@@ -394,7 +401,7 @@ mod tests {
             }
             ResourceMetrics {
                 resource: Some(resource),
-                schema_url: "".to_string(), // todo: replace with actual schema url.
+                schema_url: "".to_string(),
                 instrumentation_library_metrics,
             }
         }

opentelemetry-otlp/src/transform/resource.rs

@@ -25,6 +25,14 @@ impl PartialOrd for ResourceWrapper {
     }
 }
 
+impl ResourceWrapper {
+    #[cfg(all(feature = "grpc-tonic", feature = "metrics"))]
+    // it's currently only used by metrics. Trace set this in opentelemtry-proto
+    pub(crate) fn schema_url(&self) -> Option<&str> {
+        self.0.schema_url()
+    }
+}
+
 #[cfg(feature = "grpc-tonic")]
 impl From<ResourceWrapper> for Resource {
     fn from(resource: ResourceWrapper) -> Self {

opentelemetry-proto/src/transform/traces.rs

@@ -57,7 +57,10 @@ pub mod tonic {
                     .0,
                     dropped_attributes_count: 0,
                 }),
-                schema_url: "".to_string(), // todo: replace with actual schema url.
+                schema_url: source_span
+                    .resource
+                    .and_then(|resource| resource.schema_url().map(|url| url.to_string()))
+                    .unwrap_or_default(),
                 instrumentation_library_spans: vec![InstrumentationLibrarySpans {
                     schema_url: source_span
                         .instrumentation_lib

opentelemetry-sdk/src/resource/mod.rs

@@ -30,6 +30,7 @@ pub use process::ProcessResourceDetector;
 #[cfg(feature = "metrics")]
 use opentelemetry_api::attributes;
 use opentelemetry_api::{Key, KeyValue, Value};
+use std::borrow::Cow;
 use std::collections::{btree_map, BTreeMap};
 use std::ops::Deref;
 use std::time::Duration;
@@ -38,6 +39,7 @@ use std::time::Duration;
 #[derive(Clone, Debug, PartialEq)]
 pub struct Resource {
     attrs: BTreeMap<Key, Value>,
+    schema_url: Option<Cow<'static, str>>,
 }
 
 impl Default for Resource {
@@ -54,6 +56,7 @@ impl Resource {
     pub fn empty() -> Self {
         Self {
             attrs: Default::default(),
+            schema_url: None,
         }
     }
 
@@ -71,6 +74,24 @@ impl Resource {
         resource
     }
 
+    /// Create a new `Resource` from a key value pairs and [schema url].
+    ///
+    /// Values are de-duplicated by key, and the first key-value pair with a non-empty string value
+    /// will be retained.
+    ///
+    /// schema_url must be a valid URL using HTTP or HTTPS protocol.
+    ///
+    /// [schema url]: https://github.com/open-telemetry/opentelemetry-specification/blob/v1.9.0/specification/schemas/overview.md#schema-url
+    pub fn from_schema_url<KV, S>(kvs: KV, schema_url: S) -> Self
+    where
+        KV: IntoIterator<Item = KeyValue>,
+        S: Into<Cow<'static, str>>,
+    {
+        let mut resource = Self::new(kvs);
+        resource.schema_url = Some(schema_url.into());
+        resource
+    }
+
     /// Create a new `Resource` from resource detectors.
     ///
     /// timeout will be applied to each detector.
@@ -89,8 +110,19 @@ impl Resource {
 
     /// Create a new `Resource` by combining two resources.
     ///
+    /// ### Key value pairs
     /// Keys from the `other` resource have priority over keys from this resource, even if the
     /// updated value is empty.
+    ///
+    /// ### [Schema url]
+    /// If both of the resource are not empty. Schema url is determined by the following rules, in order:
+    /// 1. If this resource has a schema url, it will be used.
+    /// 2. If this resource does not have a schema url, and the other resource has a schema url, it will be used.
+    /// 3. If both resources have a schema url and it's the same, it will be used.
+    /// 4. If both resources have a schema url and it's different, the schema url will be empty.
+    /// 5. If both resources do not have a schema url, the schema url will be empty.
+    ///
+    /// [Schema url]: https://github.com/open-telemetry/opentelemetry-specification/blob/v1.9.0/specification/schemas/overview.md#schema-url
     pub fn merge<T: Deref<Target = Self>>(&self, other: T) -> Self {
         if self.attrs.is_empty() {
             return other.clone();
@@ -109,9 +141,31 @@ impl Resource {
             resource.attrs.insert(k.clone(), v.clone());
         }
 
+        if self.schema_url == other.schema_url {
+            resource.schema_url = self.schema_url.clone();
+        } else if self.schema_url.is_none() {
+            // if the other resource has schema url, use it.
+            if other.schema_url.is_some() {
+                resource.schema_url = other.schema_url.clone();
+            }
+            // else empty schema url.
+        } else {
+            // if self has schema url, use it.
+            if other.schema_url.is_none() {
+                resource.schema_url = self.schema_url.clone();
+            }
+        }
+
         resource
     }
 
+    /// Return the [schema url] of the resource. If the resource does not have a schema url, return `None`.
+    ///
+    /// [schema url]: https://github.com/open-telemetry/opentelemetry-specification/blob/v1.9.0/specification/schemas/overview.md#schema-url
+    pub fn schema_url(&self) -> Option<&str> {
+        self.schema_url.as_ref().map(|s| s.as_ref())
+    }
+
     /// Returns the number of attributes for this resource
     pub fn len(&self) -> usize {
         self.attrs.len()
@@ -215,13 +269,14 @@ mod tests {
         assert_eq!(
             Resource::new(args_with_dupe_keys),
             Resource {
-                attrs: expected_attrs
+                attrs: expected_attrs,
+                schema_url: None,
             }
         );
     }
 
     #[test]
-    fn merge_resource() {
+    fn merge_resource_key_value_pairs() {
         let resource_a = Resource::new(vec![
             KeyValue::new("a", ""),
             KeyValue::new("b", "b-value"),
@@ -243,11 +298,47 @@ mod tests {
         assert_eq!(
             resource_a.merge(&resource_b),
             Resource {
-                attrs: expected_attrs
+                attrs: expected_attrs,
+                schema_url: None,
             }
         );
     }
 
+    #[test]
+    fn merge_resource_schema_url() {
+        // if both resources contains key value pairs
+        let test_cases = vec![
+            (Some("http://schema/a"), None, Some("http://schema/a")),
+            (Some("http://schema/a"), Some("http://schema/b"), None),
+            (None, Some("http://schema/b"), Some("http://schema/b")),
+            (
+                Some("http://schema/a"),
+                Some("http://schema/a"),
+                Some("http://schema/a"),
+            ),
+            (None, None, None),
+        ];
+
+        for (schema_url, other_schema_url, expect_schema_url) in test_cases.into_iter() {
+            let mut resource = Resource::new(vec![KeyValue::new("key", "")]);
+            resource.schema_url = schema_url.map(Into::into);
+
+            let mut other_resource = Resource::new(vec![KeyValue::new("key", "")]);
+            other_resource.schema_url = other_schema_url.map(Into::into);
+
+            assert_eq!(
+                resource.merge(&other_resource).schema_url,
+                expect_schema_url.map(Into::into)
+            );
+        }
+
+        // if only one resource contains key value pairs
+        let resource = Resource::from_schema_url(vec![], "http://schema/a");
+        let other_resource = Resource::new(vec![KeyValue::new("key", "")]);
+
+        assert_eq!(resource.merge(&other_resource).schema_url, None);
+    }
+
     #[test]
     fn detect_resource() {
         env::set_var("OTEL_RESOURCE_ATTRIBUTES", "key=value, k = v , a= x, a=z");
@@ -262,7 +353,7 @@ mod tests {
                 KeyValue::new("key", "value"),
                 KeyValue::new("k", "v"),
                 KeyValue::new("a", "x"),
-                KeyValue::new("a", "z")
+                KeyValue::new("a", "z"),
             ])
         )
     }