Switch OTLP exporter from gRPC/tonic to HTTP/reqwest

gRPC requires special reverse proxy config for HTTP/2. HTTP works
behind standard HTTPS proxies like Traefik/Caddy on port 4318.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

compliance-core/Cargo.toml

@@ -32,7 +32,7 @@ bson = { version = "2", features = ["chrono-0_4"] }
 mongodb = { workspace = true, optional = true }
 opentelemetry = { version = "0.29", optional = true }
 opentelemetry_sdk = { version = "0.29", features = ["rt-tokio"], optional = true }
-opentelemetry-otlp = { version = "0.29", features = ["grpc-tonic"], optional = true }
+opentelemetry-otlp = { version = "0.29", features = ["http", "reqwest-client"], optional = true }
 opentelemetry-appender-tracing = { version = "0.29", optional = true }
 tracing-opentelemetry = { version = "0.30", optional = true }
 tracing-subscriber = { workspace = true, optional = true }

compliance-core/src/telemetry.rs

@@ -1,6 +1,6 @@
 //! OpenTelemetry initialization for traces and logs.
 //!
-//! Exports traces and logs via OTLP (gRPC) when `OTEL_EXPORTER_OTLP_ENDPOINT`
+//! Exports traces and logs via OTLP/HTTP when `OTEL_EXPORTER_OTLP_ENDPOINT`
 //! is set. Always includes a `tracing_subscriber::fmt` layer for console output.
 //!
 //! Compatible with SigNoz, Grafana Tempo/Loki, Jaeger, and any OTLP-compatible
@@ -10,7 +10,7 @@
 //!
 //! | Variable | Description | Default |
 //! |---|---|---|
-//! | `OTEL_EXPORTER_OTLP_ENDPOINT` | OTLP collector endpoint (e.g. `http://localhost:4317`) | *(disabled)* |
+//! | `OTEL_EXPORTER_OTLP_ENDPOINT` | OTLP collector endpoint (e.g. `https://otel.example.com`) | *(disabled)* |
 //! | `OTEL_SERVICE_NAME` | Service name for resource | `service_name` param |
 //! | `RUST_LOG` / standard `EnvFilter` | Log level filter | `info` |
 
@@ -58,7 +58,7 @@ fn build_resource(service_name: &str) -> Resource {
 /// Initialize telemetry (tracing + logging).
 ///
 /// If `OTEL_EXPORTER_OTLP_ENDPOINT` is set, traces and logs are exported
-/// via OTLP/gRPC. Console fmt output is always enabled.
+/// via OTLP/HTTP. Console fmt output is always enabled.
 ///
 /// Returns a [`TelemetryGuard`] that must be held alive for the application
 /// lifetime. Dropping it triggers a graceful shutdown of OTel providers.
@@ -76,11 +76,14 @@ pub fn init_telemetry(service_name: &str) -> TelemetryGuard {
         Some(ref endpoint) => {
             let resource = build_resource(service_name);
 
+            let traces_endpoint = format!("{endpoint}/v1/traces");
+            let logs_endpoint = format!("{endpoint}/v1/logs");
+
             // Traces
             #[allow(clippy::expect_used)]
             let span_exporter = SpanExporter::builder()
-                .with_tonic()
-                .with_endpoint(endpoint)
+                .with_http()
+                .with_endpoint(&traces_endpoint)
                 .build()
                 .expect("failed to create OTLP span exporter");
 
@@ -96,8 +99,8 @@ pub fn init_telemetry(service_name: &str) -> TelemetryGuard {
             // Logs
             #[allow(clippy::expect_used)]
             let log_exporter = LogExporter::builder()
-                .with_tonic()
-                .with_endpoint(endpoint)
+                .with_http()
+                .with_endpoint(&logs_endpoint)
                 .build()
                 .expect("failed to create OTLP log exporter");
 
@@ -111,7 +114,6 @@ pub fn init_telemetry(service_name: &str) -> TelemetryGuard {
             // Filter to prevent telemetry-induced-telemetry loops
             let otel_filter = EnvFilter::new("info")
                 .add_directive("hyper=off".parse().unwrap_or_default())
-                .add_directive("tonic=off".parse().unwrap_or_default())
                 .add_directive("h2=off".parse().unwrap_or_default())
                 .add_directive("reqwest=off".parse().unwrap_or_default());
 
@@ -125,7 +127,7 @@ pub fn init_telemetry(service_name: &str) -> TelemetryGuard {
             tracing::info!(
                 endpoint = endpoint.as_str(),
                 service = service_name,
-                "OpenTelemetry OTLP export enabled"
+                "OpenTelemetry OTLP/HTTP export enabled"
             );
 
             TelemetryGuard {