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, 6 insertions, 2 deletions

diff --git a/tvix/castore/src/directoryservice/from_addr.rs b/tvix/castore/src/directoryservice/from_addr.rs
index ee675ca68a9f..9aa01df171d7 100644
--- a/tvix/castore/src/directoryservice/from_addr.rs
+++ b/tvix/castore/src/directoryservice/from_addr.rs
@@ -63,8 +63,12 @@ pub async fn from_addr(uri: &str) -> Result<Box<dyn DirectoryService>, crate::Er
             // - In the case of unix sockets, there must be a path, but may not be a host.
             // - In the case of non-unix sockets, there must be a host, but no path.
             // Constructing the channel is handled by tvix_castore::channel::from_url.
-            let client = DirectoryServiceClient::new(crate::tonic::channel_from_url(&url).await?);
-            Box::new(GRPCDirectoryService::from_client(client))
+            Box::new(GRPCDirectoryService::from_client(
+                DirectoryServiceClient::with_interceptor(
+                    crate::tonic::channel_from_url(&url).await?,
+                    tvix_tracing::propagate::tonic::send_trace,
+                ),
+            ))
         }
         scheme if scheme.starts_with("objectstore+") => {
             // We need to convert the URL to string, strip the prefix there, and then