5 files changed, 54 insertions, 30 deletions
diff --git a/src/api/Cargo.toml b/src/api/Cargo.toml
index db77cf38..ce2d11c0 100644
--- a/src/api/Cargo.toml
+++ b/src/api/Cargo.toml
@@ -54,9 +54,11 @@ quick-xml = { version = "0.21", features = [ "serialize" ] }
 url = "2.1"
 
 opentelemetry = "0.17"
-opentelemetry-prometheus = "0.10"
-opentelemetry-otlp = "0.10"
-prometheus = "0.13"
+opentelemetry-prometheus = { version = "0.10", optional = true }
+opentelemetry-otlp = { version = "0.10", optional = true }
+prometheus = { version = "0.13", optional = true }
 
 [features]
 k2v = [ "garage_util/k2v", "garage_model/k2v" ]
+metrics = [ "opentelemetry-prometheus", "prometheus" ]
+telemetry-otlp = ["opentelemetry-otlp"]
diff --git a/src/api/admin/api_server.rs b/src/api/admin/api_server.rs
index c3b16715..d871d4e2 100644
--- a/src/api/admin/api_server.rs
+++ b/src/api/admin/api_server.rs
@@ -3,13 +3,14 @@ use std::sync::Arc;
 use async_trait::async_trait;
 
 use futures::future::Future;
-use http::header::{
-	ACCESS_CONTROL_ALLOW_METHODS, ACCESS_CONTROL_ALLOW_ORIGIN, ALLOW, CONTENT_TYPE,
-};
+use http::header::{ACCESS_CONTROL_ALLOW_METHODS, ACCESS_CONTROL_ALLOW_ORIGIN, ALLOW};
 use hyper::{Body, Request, Response};
 
-use opentelemetry::trace::{SpanRef, Tracer};
+use opentelemetry::trace::SpanRef;
+
+#[cfg(feature = "metrics")]
 use opentelemetry_prometheus::PrometheusExporter;
+#[cfg(feature = "metrics")]
 use prometheus::{Encoder, TextEncoder};
 
 use garage_model::garage::Garage;
@@ -25,6 +26,7 @@ use crate::admin::router::{Authorization, Endpoint};
 
 pub struct AdminApiServer {
 	garage: Arc<Garage>,
+	#[cfg(feature = "metrics")]
 	exporter: PrometheusExporter,
 	metrics_token: Option<String>,
 	admin_token: Option<String>,
@@ -32,7 +34,6 @@ pub struct AdminApiServer {
 
 impl AdminApiServer {
 	pub fn new(garage: Arc<Garage>) -> Self {
-		let exporter = opentelemetry_prometheus::exporter().init();
 		let cfg = &garage.config.admin;
 		let metrics_token = cfg
 			.metrics_token
@@ -44,7 +45,8 @@ impl AdminApiServer {
 			.map(|tok| format!("Bearer {}", tok));
 		Self {
 			garage,
-			exporter,
+			#[cfg(feature = "metrics")]
+			exporter: opentelemetry_prometheus::exporter().init(),
 			metrics_token,
 			admin_token,
 		}
@@ -71,22 +73,31 @@ impl AdminApiServer {
 	}
 
 	fn handle_metrics(&self) -> Result<Response<Body>, Error> {
-		let mut buffer = vec![];
-		let encoder = TextEncoder::new();
-
-		let tracer = opentelemetry::global::tracer("garage");
-		let metric_families = tracer.in_span("admin/gather_metrics", |_| {
-			self.exporter.registry().gather()
-		});
-
-		encoder
-			.encode(&metric_families, &mut buffer)
-			.ok_or_internal_error("Could not serialize metrics")?;
-
-		Ok(Response::builder()
-			.status(200)
-			.header(CONTENT_TYPE, encoder.format_type())
-			.body(Body::from(buffer))?)
+		#[cfg(feature = "metrics")]
+		{
+			use opentelemetry::trace::Tracer;
+
+			let mut buffer = vec![];
+			let encoder = TextEncoder::new();
+
+			let tracer = opentelemetry::global::tracer("garage");
+			let metric_families = tracer.in_span("admin/gather_metrics", |_| {
+				self.exporter.registry().gather()
+			});
+
+			encoder
+				.encode(&metric_families, &mut buffer)
+				.ok_or_internal_error("Could not serialize metrics")?;
+
+			Ok(Response::builder()
+				.status(200)
+				.header(http::header::CONTENT_TYPE, encoder.format_type())
+				.body(Body::from(buffer))?)
+		}
+		#[cfg(not(feature = "metrics"))]
+		Err(Error::bad_request(
+			"Garage was built without the metrics feature".to_string(),
+		))
 	}
 }
 
diff --git a/src/garage/Cargo.toml b/src/garage/Cargo.toml
index e19aac50..553ac57a 100644
--- a/src/garage/Cargo.toml
+++ b/src/garage/Cargo.toml
@@ -55,9 +55,9 @@ tokio = { version = "1.0", default-features = false, features = ["rt", "rt-multi
 netapp = "0.4"
 
 opentelemetry = { version = "0.17", features = [ "rt-tokio" ] }
-opentelemetry-prometheus = "0.10"
-opentelemetry-otlp = "0.10"
-prometheus = "0.13"
+opentelemetry-prometheus = { version = "0.10", optional = true }
+opentelemetry-otlp = { version = "0.10", optional = true }
+prometheus = { version = "0.13", optional = true }
 
 [dev-dependencies]
 aws-sdk-s3 = "0.8"
@@ -74,9 +74,13 @@ base64 = "0.13"
 
 
 [features]
-default = [ "bundled-libs" ]
+default = [ "bundled-libs", "metrics" ]
 kubernetes-discovery = [ "garage_rpc/kubernetes-discovery" ]
 k2v = [ "garage_util/k2v", "garage_api/k2v" ]
+# Prometheus exporter (/metrics endpoint).
+metrics = [ "garage_api/metrics", "opentelemetry-prometheus", "prometheus" ]
+# Exporter for the OpenTelemetry Collector.
+telemetry-otlp = [ "opentelemetry-otlp", "garage_api/telemetry-otlp" ]
 
 # NOTE: bundled-libs and system-libs should be treat as mutually exclusive;
 # exactly one of them should be enabled.
diff --git a/src/garage/main.rs b/src/garage/main.rs
index 89888884..8f0b377e 100644
--- a/src/garage/main.rs
+++ b/src/garage/main.rs
@@ -8,6 +8,7 @@ mod admin;
 mod cli;
 mod repair;
 mod server;
+#[cfg(feature = "telemetry-otlp")]
 mod tracing_setup;
 
 use std::net::SocketAddr;
diff --git a/src/garage/server.rs b/src/garage/server.rs
index 6321357a..d328c044 100644
--- a/src/garage/server.rs
+++ b/src/garage/server.rs
@@ -15,6 +15,7 @@ use garage_web::run_web_server;
 use garage_api::k2v::api_server::K2VApiServer;
 
 use crate::admin::*;
+#[cfg(feature = "telemetry-otlp")]
 use crate::tracing_setup::*;
 
 async fn wait_from(mut chan: watch::Receiver<bool>) {
@@ -36,9 +37,14 @@ pub async fn run_server(config_file: PathBuf) -> Result<(), Error> {
 	info!("Initializing Garage main data store...");
 	let garage = Garage::new(config.clone(), background)?;
 
-	info!("Initialize tracing...");
 	if let Some(export_to) = config.admin.trace_sink {
+		info!("Initialize tracing...");
+
+		#[cfg(feature = "telemetry-otlp")]
 		init_tracing(&export_to, garage.system.id)?;
+
+		#[cfg(not(feature = "telemetry-otlp"))]
+		warn!("Garage was built without OTLP exporter, admin.trace_sink is ignored.");
 	}
 
 	info!("Initialize Admin API server and metrics collector...");