feat(observability): Phase 6 OTLP tracing for gRPC + config helper

- libs/rpc: slog → tracing; 8 gRPC methods instrumented with
  info_span + Instrument for W3C trace propagation
- libs/session_manager: slog → tracing dependency
- libs/config: add redis_url() singleton helper for adminrpc

libs/config/redis.rs

@@ -1,6 +1,14 @@
 use crate::AppConfig;
 
 impl AppConfig {
+    /// Returns a single Redis URL (first from APP_REDIS_URLS or APP_REDIS_URL).
+    pub fn redis_url(&self) -> anyhow::Result<String> {
+        let urls = self.redis_urls()?;
+        urls.into_iter().next().ok_or_else(|| {
+            anyhow::anyhow!("APP_REDIS_URLS or APP_REDIS_URL is empty")
+        })
+    }
+
     pub fn redis_urls(&self) -> anyhow::Result<Vec<String>> {
         if let Some(urls) = self.env.get("APP_REDIS_URLS") {
             return Ok(urls.split(',').map(|s| s.trim().to_string()).collect());

libs/rpc/Cargo.toml

@@ -19,12 +19,13 @@ name = "rpc"
 tonic = { workspace = true }
 prost = { workspace = true }
 prost-types = { workspace = true }
+tonic-prost = "0.14.5"
 
 # Internal
 session_manager = { workspace = true }
 
-# Logging
+# Logging / Tracing
-slog = { workspace = true }
+tracing = { workspace = true }
 
 # Utilities
 anyhow = { workspace = true }

libs/rpc/admin/mod.rs

@@ -0,0 +1,4 @@
+pub mod client;
+pub mod generated;
+pub mod server;
+pub mod types;

libs/rpc/admin/server.rs

@@ -4,6 +4,7 @@ use session_manager::SessionManager;
 use std::net::SocketAddr;
 use tokio::sync::broadcast;
 use tonic::{transport::Server, Request, Response, Status};
+use tracing::{info_span, Instrument};
 
 use super::generated::admin::{
     GetUserInfoRequest, GetUserInfoResponse, GetUserStatusRequest, GetUserStatusResponse,
@@ -37,6 +38,7 @@ impl SessionAdmin for SessionAdminService {
         let workspace_id = parse_uuid(&req.get_ref().workspace_id)
             .ok_or_else(|| Status::invalid_argument("invalid workspace_id"))?;
 
+        async {
             let sessions = self
                 .session_manager
                 .get_workspace_sessions(&workspace_id)
@@ -46,6 +48,9 @@ impl SessionAdmin for SessionAdminService {
             let sessions = sessions.iter().map(to_proto_session).collect();
             Ok(Response::new(ListWorkspaceSessionsResponse { sessions }))
         }
+        .instrument(info_span!("list_workspace_sessions", workspace_id = %workspace_id))
+        .await
+    }
 
     async fn list_user_sessions(
         &self,
@@ -54,6 +59,7 @@ impl SessionAdmin for SessionAdminService {
         let user_id = parse_uuid(&req.get_ref().user_id)
             .ok_or_else(|| Status::invalid_argument("invalid user_id"))?;
 
+        async {
             let sessions = self
                 .session_manager
                 .get_user_sessions(&user_id)
@@ -63,6 +69,9 @@ impl SessionAdmin for SessionAdminService {
             let sessions = sessions.iter().map(to_proto_session).collect();
             Ok(Response::new(ListUserSessionsResponse { sessions }))
         }
+        .instrument(info_span!("list_user_sessions", user_id = %user_id))
+        .await
+    }
 
     async fn kick_user_from_workspace(
         &self,
@@ -74,6 +83,7 @@ impl SessionAdmin for SessionAdminService {
         let workspace_id = parse_uuid(&r.workspace_id)
             .ok_or_else(|| Status::invalid_argument("invalid workspace_id"))?;
 
+        async {
             let kicked_count = self
                 .session_manager
                 .kick_user_from_workspace(&user_id, &workspace_id)
@@ -84,6 +94,9 @@ impl SessionAdmin for SessionAdminService {
                 kicked_count: kicked_count as u32,
             }))
         }
+        .instrument(info_span!("kick_user_from_workspace", user_id = %user_id, workspace_id = %workspace_id))
+        .await
+    }
 
     async fn kick_user(
         &self,
@@ -92,6 +105,7 @@ impl SessionAdmin for SessionAdminService {
         let user_id = parse_uuid(&req.get_ref().user_id)
             .ok_or_else(|| Status::invalid_argument("invalid user_id"))?;
 
+        async {
             let kicked_count = self
                 .session_manager
                 .kick_user(&user_id)
@@ -102,6 +116,9 @@ impl SessionAdmin for SessionAdminService {
                 kicked_count: kicked_count as u32,
             }))
         }
+        .instrument(info_span!("kick_user", user_id = %user_id))
+        .await
+    }
 
     async fn get_user_status(
         &self,
@@ -110,6 +127,7 @@ impl SessionAdmin for SessionAdminService {
         let user_id = parse_uuid(&req.get_ref().user_id)
             .ok_or_else(|| Status::invalid_argument("invalid user_id"))?;
 
+        async {
             let status = self
                 .session_manager
                 .get_user_status(&user_id)
@@ -120,6 +138,9 @@ impl SessionAdmin for SessionAdminService {
                 status: to_proto_status(status) as i32,
             }))
         }
+        .instrument(info_span!("get_user_status", user_id = %user_id))
+        .await
+    }
 
     async fn get_user_info(
         &self,
@@ -128,6 +149,7 @@ impl SessionAdmin for SessionAdminService {
         let user_id = parse_uuid(&req.get_ref().user_id)
             .ok_or_else(|| Status::invalid_argument("invalid user_id"))?;
 
+        async {
             let info = self
                 .session_manager
                 .get_user_info(&user_id)
@@ -138,6 +160,9 @@ impl SessionAdmin for SessionAdminService {
                 info: info.as_ref().map(to_proto_info),
             }))
         }
+        .instrument(info_span!("get_user_info", user_id = %user_id))
+        .await
+    }
 
     async fn get_workspace_online_users(
         &self,
@@ -146,6 +171,7 @@ impl SessionAdmin for SessionAdminService {
         let workspace_id = parse_uuid(&req.get_ref().workspace_id)
             .ok_or_else(|| Status::invalid_argument("invalid workspace_id"))?;
 
+        async {
             let user_ids = self
                 .session_manager
                 .get_workspace_online_users(&workspace_id)
@@ -155,6 +181,9 @@ impl SessionAdmin for SessionAdminService {
             let user_ids = user_ids.iter().map(|u| u.to_string()).collect();
             Ok(Response::new(GetWorkspaceOnlineUsersResponse { user_ids }))
         }
+        .instrument(info_span!("get_workspace_online_users", workspace_id = %workspace_id))
+        .await
+    }
 
     async fn is_user_online(
         &self,
@@ -163,6 +192,7 @@ impl SessionAdmin for SessionAdminService {
         let user_id = parse_uuid(&req.get_ref().user_id)
             .ok_or_else(|| Status::invalid_argument("invalid user_id"))?;
 
+        async {
             let online = self
                 .session_manager
                 .is_user_online(&user_id)
@@ -171,6 +201,9 @@ impl SessionAdmin for SessionAdminService {
 
             Ok(Response::new(IsUserOnlineResponse { online }))
         }
+        .instrument(info_span!("is_user_online", user_id = %user_id))
+        .await
+    }
 }
 
 /// Default gRPC admin port.

libs/session_manager/Cargo.toml

@@ -26,7 +26,7 @@ serde_json = { workspace = true }
 thiserror = { workspace = true }
 tokio = { workspace = true, features = ["rt-multi-thread", "sync"] }
 uuid = { workspace = true, features = ["serde", "v4"] }
-slog = { workspace = true }
+tracing = { workspace = true }
 
 [lints]
 workspace = true