feat(cli): opt-in OTLP/HTTP export for tracing spans

Cargo.toml

@@ -64,6 +64,18 @@ git2 = { version = "0.20", default-features = false, features = ["vendored-libgi
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", features = ["fmt", "env-filter"] }
 tracing-appender = "0.2"
+# Opt-in OTLP/HTTP export of fabro's existing `tracing` spans (see
+# fabro-cli/src/otel.rs). Additive and inert unless an OTLP endpoint env is set.
+# Uses the BLOCKING OTLP client (the crate's own default) so the SDK batch
+# processor's dedicated export thread needs no async runtime. NOTE:
+# opentelemetry-otlp's `http-proto`/`http-json` features enable `metrics`
+# unconditionally, so the trace+metrics SDK is compiled regardless — a trace-only
+# reduction is not achievable while using the HTTP exporter. `opentelemetry-otlp`
+# keeps `default-features = false` only to drop its unused OTLP logs exporter.
+opentelemetry = "0.30"
+opentelemetry_sdk = "0.30"
+opentelemetry-otlp = { version = "0.30", default-features = false, features = ["trace", "http-proto", "http-json", "reqwest-blocking-client"] }
+tracing-opentelemetry = "0.31"
 rmcp = { version = "1.4", default-features = false }
 walkdir = "2"
 regex = "1"

lib/crates/fabro-cli/Cargo.toml

@@ -66,6 +66,10 @@ tokio-tungstenite.workspace = true
 tracing.workspace = true
 tracing-subscriber.workspace = true
 tracing-appender.workspace = true
+opentelemetry.workspace = true
+opentelemetry_sdk.workspace = true
+opentelemetry-otlp.workspace = true
+tracing-opentelemetry.workspace = true
 chrono = { workspace = true, features = ["serde"] }
 dirs.workspace = true
 fs2.workspace = true

lib/crates/fabro-cli/src/logging.rs

@@ -22,6 +22,8 @@ use tracing_subscriber::registry::LookupSpan;
 use tracing_subscriber::util::SubscriberInitExt;
 use tracing_subscriber::{EnvFilter, fmt};
 
+use crate::otel;
+
 const LOG_RETENTION_DAYS: u32 = 7;
 
 #[derive(Clone, Debug, PartialEq, Eq)]
@@ -362,6 +364,8 @@ where
                 .with_target(true)
                 .with_ansi(false),
         )
+        // Additive OTLP export: no-op unless an OTLP endpoint env is set.
+        .with(otel::otel_layer())
         .init();
 }
 
@@ -384,6 +388,8 @@ where
                 .with_ansi(ansi)
                 .event_format(TtyLogFormat::new(ansi)),
         )
+        // Additive OTLP export: no-op unless an OTLP endpoint env is set.
+        .with(otel::otel_layer())
         .init();
 }
 
@@ -409,6 +415,8 @@ fn init_worker_subscriber<ServerWriter, RunWriter>(
                 .with_target(true)
                 .with_ansi(false),
         )
+        // Additive OTLP export: no-op unless an OTLP endpoint env is set.
+        .with(otel::otel_layer())
         .init();
 }
 
@@ -441,6 +449,8 @@ fn init_worker_stdout_subscriber<ServerWriter, RunWriter>(
                 .with_target(true)
                 .with_ansi(false),
         )
+        // Additive OTLP export: no-op unless an OTLP endpoint env is set.
+        .with(otel::otel_layer())
         .init();
 }
 

lib/crates/fabro-cli/src/main.rs

@@ -11,6 +11,7 @@ mod landing;
 mod local_server;
 mod logging;
 mod manifest_args;
+mod otel;
 mod server_client;
 mod server_runs;
 mod shared;
@@ -113,6 +114,9 @@ async fn main() {
         }
     }
     fabro_telemetry::shutdown();
+    // Best-effort final drain of the OTLP span batch on normal exit (no-op when
+    // OTLP is not configured; the batch processor also exports periodically).
+    otel::shutdown();
 
     if let Err(err) = result {
         let json_mode = raw_args.iter().any(|a| a == "--json");