feat(tvix/tracing): gRPC trace context propagation r/8299

This introduces optional helper function in tvix/tracing for trace
propagation and uses these helper in the `tvix-store`.

The GRPCBlobService, GRPCDirectoryService and GRPCPathInfoService now
accept a generic client, meaning the client can be generated with either
`::new` or `::with_interceptor`.

This was tested and validated by starting a `tvix-store daemon` and
`tvix-store import`.

Change-Id: I4b194483bf09266820104b4b56e4a135dca2b77a
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11863
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

1 files changed, 7 insertions, 0 deletions

diff --git a/tvix/tracing/src/lib.rs b/tvix/tracing/src/lib.rs
index 68a417998a24..b965ca4a3dbc 100644
--- a/tvix/tracing/src/lib.rs
+++ b/tvix/tracing/src/lib.rs
@@ -9,6 +9,7 @@ use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt, EnvFilte
 use opentelemetry::{trace::Tracer, KeyValue};
 #[cfg(feature = "otlp")]
 use opentelemetry_sdk::{
+    propagation::TraceContextPropagator,
     resource::{ResourceDetector, SdkProvidedResourceDetector},
     trace::BatchConfigBuilder,
     Resource,
@@ -16,6 +17,9 @@ use opentelemetry_sdk::{
 #[cfg(feature = "tracy")]
 use tracing_tracy::TracyLayer;
 
+#[cfg(feature = "tonic")] // TODO or http
+pub mod propagate;
+
 lazy_static! {
     pub static ref PB_PROGRESS_STYLE: ProgressStyle = ProgressStyle::with_template(
         "{span_child_prefix} {wide_msg} {bar:10} ({elapsed}) {pos:>7}/{len:7}"
@@ -186,6 +190,9 @@ impl TracingBuilder {
         #[cfg(feature = "otlp")]
         {
             if let Some(service_name) = self.service_name {
+                // register a text map propagator for trace propagation
+                opentelemetry::global::set_text_map_propagator(TraceContextPropagator::new());
+
                 let (tracer, tx) = gen_otlp_tracer(service_name.to_string());
                 // Create a tracing layer with the configured tracer
                 let layer = tracing_opentelemetry::layer().with_tracer(tracer);