Hide opentelemetry behind feature flag

Cargo.toml

@@ -16,6 +16,16 @@ repository.workspace = true
 resolver = "2"
 publish = false
 
+[features]
+debug = ["opentelemetry"]
+opentelemetry = [
+  "dep:opentelemetry",
+  "dep:opentelemetry-otlp",
+  "dep:opentelemetry_sdk",
+  "dep:opentelemetry-semantic-conventions",
+  "dep:tracing-opentelemetry",
+]
+
 [profile.dev]
 debug = 0
 
@@ -122,12 +132,14 @@ sqlx = { workspace = true }
 async-trait = { workspace = true }
 tracing-actix-web = { workspace = true }
 
-opentelemetry = "0.27"
-opentelemetry-otlp = "0.27"
-opentelemetry_sdk = { version = "0.27", features = ["rt-tokio"] }
+opentelemetry = { version = "0.27", optional = true }
+opentelemetry-otlp = { version = "0.27", optional = true }
+opentelemetry_sdk = { version = "0.27", features = [
+  "rt-tokio",
+], optional = true }
+opentelemetry-semantic-conventions = { version = "0.27", optional = true }
+tracing-opentelemetry = { version = "0.28", optional = true }
 
-opentelemetry-semantic-conventions = "0.27"
-tracing-opentelemetry = "0.28"
 tracing-subscriber = { version = "0.3", features = [
   "env-filter",
   "fmt",

README.md

@@ -3,9 +3,9 @@
 a CalDAV/CardDAV server
 
 > [!CAUTION]
-> RustiCal is **not production-ready!**
-> There can be changes to the database without migrations and there's no guarantee that all endpoints are secured yet.
-> If you still want to play around with it in its current state, absolutely feel free to do so but know that not even I use it productively yet.
+> If you're installing RustiCal, you are a very early adopter!
+>
+> - You should be unafraid to inspect the SQLite database yourself if something goes wrong in the future
 
 ## Features
 
@@ -41,8 +41,7 @@ You can generate a default `config.toml` with
 rustical gen-config
 ```
 
-> [!WARNING]
-> `rustical gen-config` generates a random `frontend.secret_key`.
+> [!WARNING] > `rustical gen-config` generates a random `frontend.secret_key`.
 > This secret is used to generate session cookies so if it is leaked an attacker could use it to authenticate to against any endpoint (also when the frontend is disabled).
 
 You'll have to set your database path to something like `/var/lib/rustical/db.sqlite3`.
@@ -82,6 +81,16 @@ Since push messages are currently not encrypted you might potentially want to en
 allowed_push_servers = ["https://your-instance-ntfy.sh"]
 ```
 
+## Debugging
+
+RustiCal supports exporting opentelemetry traces to inspect with tools like [Jaeger](https://www.jaegertracing.io/).
+To enable you need to compile with the `opentelemtry` (or `debug`) feature and enable opentelemetry in the config with
+
+```toml
+[tracing]
+opentelemetry = true
+```
+
 ## Relevant RFCs
 
 - Versioning Extensions to WebDAV: [RFC 3253](https://datatracker.ietf.org/doc/html/rfc3253)

src/setup_tracing.rs

@@ -1,21 +1,28 @@
 use crate::config::TracingConfig;
-use opentelemetry::global;
-use opentelemetry::trace::TracerProvider;
-use opentelemetry::KeyValue;
+#[cfg(feature = "opentelemetry")]
+use opentelemetry::{global, trace::TracerProvider, KeyValue};
+#[cfg(feature = "opentelemetry")]
 use opentelemetry_otlp::WithExportConfig;
-use opentelemetry_sdk::propagation::TraceContextPropagator;
-use opentelemetry_sdk::trace::Tracer;
-use opentelemetry_sdk::Resource;
-use opentelemetry_semantic_conventions::resource::{SERVICE_NAME, SERVICE_VERSION};
-use opentelemetry_semantic_conventions::SCHEMA_URL;
+#[cfg(feature = "opentelemetry")]
+use opentelemetry_sdk::{propagation::TraceContextPropagator, trace::Tracer, Resource};
+#[cfg(feature = "opentelemetry")]
+use opentelemetry_semantic_conventions::{
+    resource::{SERVICE_NAME, SERVICE_VERSION},
+    SCHEMA_URL,
+};
+#[cfg(feature = "opentelemetry")]
 use std::time::Duration;
 use tracing::level_filters::LevelFilter;
+#[cfg(not(feature = "opentelemetry"))]
+use tracing::warn;
+#[cfg(feature = "opentelemetry")]
 use tracing_opentelemetry::OpenTelemetryLayer;
 use tracing_subscriber::layer::SubscriberExt;
 use tracing_subscriber::util::SubscriberInitExt;
 use tracing_subscriber::EnvFilter;
 
-pub fn init_tracer() -> Tracer {
+#[cfg(feature = "opentelemetry")]
+pub fn init_otel() -> Tracer {
     let otel_exporter = opentelemetry_otlp::SpanExporter::builder()
         .with_tonic()
         .with_timeout(Duration::from_secs(1))
@@ -51,8 +58,16 @@ pub fn setup_tracing(config: &TracingConfig) {
         .with(fmt_layer);
 
     if config.opentelemetry {
-        global::set_text_map_propagator(TraceContextPropagator::new());
-        registry.with(OpenTelemetryLayer::new(init_tracer())).init();
+        #[cfg(feature = "opentelemetry")]
+        {
+            global::set_text_map_propagator(TraceContextPropagator::new());
+            registry.with(OpenTelemetryLayer::new(init_otel())).init();
+        }
+        #[cfg(not(feature = "opentelemetry"))]
+        {
+            registry.init();
+            warn!("This version of RustiCal is compiled without the opentelemetry feature. tracing.opentelemtry = true has no effect");
+        }
     } else {
         registry.init();
     }