fix otlp/json exporter (open-telemetry#1882)

Author: lalitb

opentelemetry-otlp/CHANGELOG.md

@@ -16,6 +16,8 @@ now use `.with_resource(RESOURCE::default())` to configure Resource when using
   These methods would also no longer set the global tracer provider. It would now be the responsibility of users to set it by calling `global::set_tracer_provider(tracer_provider.clone());`. Refer to the [basic-otlp](https://github.com/open-telemetry/opentelemetry-rust/blob/main/opentelemetry-otlp/examples/basic-otlp/src/main.rs) and [basic-otlp-http](https://github.com/open-telemetry/opentelemetry-rust/blob/main/opentelemetry-otlp/examples/basic-otlp-http/src/main.rs) examples on how to initialize OTLP Trace Exporter.
 - **Breaking** Correct the misspelling of "webkpi" to "webpki" in features [#1842](https://github.com/open-telemetry/opentelemetry-rust/pull/1842)
 - Bump MSRV to 1.70 [#1840](https://github.com/open-telemetry/opentelemetry-rust/pull/1840)
+- Fixing the OTLP HTTP/JSON exporter. [#1882](https://github.com/open-telemetry/opentelemetry-rust/pull/1882) - The exporter was broken in the
+  previous release.
 
 ## v0.16.0
 

opentelemetry-otlp/tests/integration_test/src/trace_asserter.rs

@@ -216,6 +216,6 @@ fn span_eq(left: &Span, right: &Span) -> bool {
 pub fn read_spans_from_json(file: File) -> Vec<ResourceSpans> {
     let reader = std::io::BufReader::new(file);
 
-    let trace_data: TracesData = serde_json::from_reader(reader).unwrap();
+    let trace_data: TracesData = serde_json::from_reader(reader).expect("Failed to read json file");
     trace_data.resource_spans
 }

opentelemetry-otlp/tests/integration_test/tests/traces.rs

@@ -8,9 +8,11 @@ use opentelemetry::{
     trace::{TraceContextExt, Tracer},
     Key, KeyValue,
 };
+use opentelemetry_proto::tonic::trace::v1::TracesData;
 use opentelemetry_sdk::{runtime, trace as sdktrace, Resource};
 use std::error::Error;
 use std::fs::File;
+use std::io::Write;
 use std::os::unix::fs::MetadataExt;
 
 fn init_tracer_provider() -> Result<sdktrace::TracerProvider, TraceError> {
@@ -83,3 +85,28 @@ pub fn test_assert_span_eq() {
 
     TraceAsserter::new(spans.clone(), spans).assert();
 }
+
+#[test]
+pub fn test_serde() {
+    let spans = read_spans_from_json(
+        File::open("./expected/traces.json").expect("Failed to read traces.json"),
+    );
+    let json = serde_json::to_string_pretty(&TracesData {
+        resource_spans: spans,
+    })
+    .expect("Failed to serialize spans to json");
+
+    // Write to file.
+    let mut file = File::create("./expected/serialized_traces.json").unwrap();
+    file.write_all(json.as_bytes()).unwrap();
+
+    let left = read_spans_from_json(
+        File::open("./expected/traces.json").expect("Failed to read traces.json"),
+    );
+    let right = read_spans_from_json(
+        File::open("./expected/serialized_traces.json")
+            .expect("Failed to read serialized_traces.json"),
+    );
+
+    TraceAsserter::new(left, right).assert();
+}

opentelemetry-proto/src/proto.rs

@@ -46,14 +46,26 @@ pub(crate) mod serializers {
 
     // AnyValue <-> KeyValue conversion
     pub fn serialize_to_value<S>(value: &Option<AnyValue>, serializer: S) -> Result<S::Ok, S::Error>
-        where
-            S: Serializer,
+    where
+        S: Serializer,
     {
-        // Serialize any_value::Value using its own implementation
-        // If value is None, it will be serialized as such
         match value {
             Some(any_value) => match &any_value.value {
-                Some(Value::IntValue(i)) => serialize_i64_to_string(i, serializer),
+                Some(Value::IntValue(i)) => {
+                    // Attempt to create a struct to wrap the intValue
+                    let mut state = match serializer.serialize_struct("Value", 1) {
+                        Ok(s) => s,
+                        Err(e) => return Err(e), // Handle the error or return it
+                    };
+    
+                    // Attempt to serialize the intValue field
+                    if let Err(e) = state.serialize_field("intValue", &i.to_string()) {
+                        return Err(e); // Handle the error or return it
+                    }
+    
+                    // Finalize the struct serialization
+                    state.end()
+                },
                 Some(value) => value.serialize(serializer),
                 None => serializer.serialize_none(),
             },