make OTLP optional (#56)

Author: reluctanthero104

crates/server/src/main.rs

@@ -5,16 +5,19 @@ use skardi_server::{create_server, load_server_config, telemetry, CliArgs};
 use tracing::{error, info};
 use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
 
-const DEFAULT_OTLP_ENDPOINT: &str = "http://localhost:4317";
-
 #[tokio::main]
 async fn main() -> Result<()> {
-    // Initialise OpenTelemetry (traces + metrics) before the tracing subscriber
-    let otlp_endpoint =
-        std::env::var("OTLP_ENDPOINT").unwrap_or_else(|_| DEFAULT_OTLP_ENDPOINT.to_string());
-    let (_telemetry_guard, tracer) = telemetry::init(&otlp_endpoint)?;
+    // Initialise OpenTelemetry only when OTLP_ENDPOINT is explicitly set.
+    let otlp_endpoint = std::env::var("OTLP_ENDPOINT").ok();
+    let (_telemetry_guard, otel_layer) = match telemetry::init(otlp_endpoint.as_deref())? {
+        Some((guard, tracer)) => (
+            Some(guard),
+            Some(tracing_opentelemetry::layer().with_tracer(tracer)),
+        ),
+        None => (None, None),
+    };
 
-    // Initialize tracing subscriber: fmt to stdout + OTel trace export
+    // Initialize tracing subscriber: fmt to stdout, plus OTel layer when enabled.
     tracing_subscriber::registry()
         .with(
             tracing_subscriber::EnvFilter::try_from_default_env().unwrap_or_else(|_| "info".into()),
@@ -23,7 +26,7 @@ async fn main() -> Result<()> {
             tracing_subscriber::fmt::layer()
                 .with_span_events(tracing_subscriber::fmt::format::FmtSpan::CLOSE),
         )
-        .with(tracing_opentelemetry::layer().with_tracer(tracer))
+        .with(otel_layer)
         .init();
 
     info!("🚀 Starting Skardi Online Serving Pipeline Server");

crates/server/src/telemetry.rs

@@ -26,11 +26,20 @@ impl Drop for TelemetryGuard {
 
 /// Initialise OpenTelemetry traces and metrics, exporting via OTLP gRPC.
 ///
+/// Returns `None` when `otlp_endpoint` is `None` — OTLP export is disabled
+/// and no providers are registered.
+///
 /// Call this before setting up the tracing subscriber so the returned tracer
 /// can be passed into `tracing_opentelemetry::layer()`.
 ///
 /// The returned `TelemetryGuard` must be kept alive until the process exits.
-pub fn init(otlp_endpoint: &str) -> Result<(TelemetryGuard, opentelemetry_sdk::trace::Tracer)> {
+pub fn init(
+    otlp_endpoint: Option<&str>,
+) -> Result<Option<(TelemetryGuard, opentelemetry_sdk::trace::Tracer)>> {
+    let Some(otlp_endpoint) = otlp_endpoint else {
+        return Ok(None);
+    };
+
     let resource = Resource::new(vec![KeyValue::new(
         opentelemetry_semantic_conventions::resource::SERVICE_NAME,
         "skardi-server",
@@ -65,11 +74,11 @@ pub fn init(otlp_endpoint: &str) -> Result<(TelemetryGuard, opentelemetry_sdk::t
 
     global::set_meter_provider(meter_provider.clone());
 
-    Ok((
+    Ok(Some((
         TelemetryGuard {
             tracer_provider,
             meter_provider,
         },
         tracer,
-    ))
+    )))
 }