[router] refactor router and worker management 4/n (#10756)

Co-authored-by: Chang Su <chang.s.su@oracle.com>

sgl-router/src/routers/http/pd_router.rs

@@ -41,6 +41,7 @@ pub struct PDRouter {
     pub prefill_client: Client,
     pub retry_config: RetryConfig,
     pub api_key: Option<String>,
+    pub enable_igw: bool,
     prefill_drain_tx: mpsc::Sender<reqwest::Response>,
 }
 
@@ -317,6 +318,7 @@ impl PDRouter {
             prefill_drain_tx,
             retry_config: ctx.router_config.effective_retry_config(),
             api_key: ctx.router_config.api_key.clone(),
+            enable_igw: ctx.router_config.enable_igw,
         })
     }
 
@@ -849,7 +851,14 @@ impl PDRouter {
         request_text: Option<&str>,
         model_id: Option<&str>,
     ) -> Result<(Arc<dyn Worker>, Arc<dyn Worker>), String> {
-        let prefill_workers = if let Some(model) = model_id {
+        let effective_model_id = if !self.enable_igw { None } else { model_id };
+
+        debug!(
+            "Selecting PD pair: enable_igw={}, model_id={:?}, effective_model_id={:?}",
+            self.enable_igw, model_id, effective_model_id
+        );
+
+        let prefill_workers = if let Some(model) = effective_model_id {
             self.worker_registry
                 .get_by_model_fast(model)
                 .into_iter()
@@ -859,7 +868,7 @@ impl PDRouter {
             self.worker_registry.get_prefill_workers()
         };
 
-        let decode_workers = if let Some(model) = model_id {
+        let decode_workers = if let Some(model) = effective_model_id {
             self.worker_registry
                 .get_by_model_fast(model)
                 .into_iter()
@@ -1797,6 +1806,7 @@ mod tests {
             prefill_drain_tx: mpsc::channel(100).0,
             retry_config: RetryConfig::default(),
             api_key: Some("test_api_key".to_string()),
+            enable_igw: false,
         }
     }
 

sgl-router/src/routers/http/router.rs

@@ -35,6 +35,7 @@ pub struct Router {
     policy_registry: Arc<PolicyRegistry>,
     client: Client,
     dp_aware: bool,
+    enable_igw: bool,
     retry_config: RetryConfig,
     _worker_loads: Arc<tokio::sync::watch::Receiver<HashMap<String, isize>>>,
     _load_monitor_handle: Option<Arc<tokio::task::JoinHandle<()>>>,
@@ -93,6 +94,7 @@ impl Router {
             policy_registry: ctx.policy_registry.clone(),
             client: ctx.client.clone(),
             dp_aware: ctx.router_config.dp_aware,
+            enable_igw: ctx.router_config.enable_igw,
             retry_config: ctx.router_config.effective_retry_config(),
             _worker_loads: worker_loads,
             _load_monitor_handle: load_monitor_handle,
@@ -162,9 +164,11 @@ impl Router {
         model_id: Option<&str>,
         text: Option<&str>,
     ) -> Option<Arc<dyn Worker>> {
+        let effective_model_id = if !self.enable_igw { None } else { model_id };
+
         // Get workers for the specified model O(1), filtered by connection mode
         let workers = self.worker_registry.get_workers_filtered(
-            model_id,
+            effective_model_id,
             Some(WorkerType::Regular),
             Some(ConnectionMode::Http),
             false, // get all workers, we'll filter by is_available() next
@@ -1106,6 +1110,7 @@ mod tests {
             retry_config: RetryConfig::default(),
             _worker_loads: Arc::new(rx),
             _load_monitor_handle: None,
+            enable_igw: false,
         }
     }
 

sgl-router/src/routers/router_manager.rs

@@ -4,12 +4,14 @@
 //! - Single Router Mode (enable_igw=false): Router owns workers directly
 //! - Multi-Router Mode (enable_igw=true): RouterManager coordinates everything
 
-use crate::core::{Worker, WorkerRegistry, WorkerType};
+use crate::config::{ConnectionMode, RoutingMode};
+use crate::core::{WorkerRegistry, WorkerType};
 use crate::protocols::spec::{
     ChatCompletionRequest, CompletionRequest, EmbeddingRequest, GenerateRequest, RerankRequest,
     ResponsesRequest,
 };
 use crate::routers::RouterTrait;
+use crate::server::{AppContext, ServerConfig};
 use async_trait::async_trait;
 use axum::{
     body::Body,
@@ -19,9 +21,8 @@ use axum::{
 };
 use dashmap::DashMap;
 use std::sync::Arc;
-use tracing::info;
+use tracing::{debug, info, warn};
 
-/// Router identifier
 #[derive(Debug, Clone, Hash, Eq, PartialEq)]
 pub struct RouterId(String);
 
@@ -35,30 +36,120 @@ impl RouterId {
     }
 }
 
-/// Router Manager - Central coordinator for routers and workers
 pub struct RouterManager {
-    /// Worker registry (single source of truth in multi-router mode)
     worker_registry: Arc<WorkerRegistry>,
-
-    /// All routers managed by this manager
-    /// RouterId examples: "http-regular", "http-pd", "grpc-regular", "grpc-pd"
     routers: Arc<DashMap<RouterId, Arc<dyn RouterTrait>>>,
-
-    /// Default router for requests without specific routing
     default_router: Arc<std::sync::RwLock<Option<RouterId>>>,
+    enable_igw: bool,
 }
 
 impl RouterManager {
-    /// Create a new router manager with shared registries
     pub fn new(worker_registry: Arc<WorkerRegistry>) -> Self {
         Self {
             worker_registry,
             routers: Arc::new(DashMap::new()),
             default_router: Arc::new(std::sync::RwLock::new(None)),
+            enable_igw: false, // Will be set properly in from_config
+        }
+    }
+
+    pub async fn from_config(
+        config: &ServerConfig,
+        app_context: &Arc<AppContext>,
+    ) -> Result<Arc<Self>, String> {
+        use crate::routers::RouterFactory;
+
+        let mut manager = Self::new(app_context.worker_registry.clone());
+        manager.enable_igw = config.router_config.enable_igw;
+        let manager = Arc::new(manager);
+
+        if config.router_config.enable_igw {
+            info!("Initializing RouterManager in multi-router mode (IGW)");
+
+            match RouterFactory::create_regular_router(app_context).await {
+                Ok(http_regular) => {
+                    info!("Created HTTP Regular router");
+                    manager.register_router(
+                        RouterId::new("http-regular".to_string()),
+                        Arc::from(http_regular),
+                    );
+                }
+                Err(e) => {
+                    warn!("Failed to create HTTP Regular router: {e}");
+                }
+            }
+
+            match RouterFactory::create_pd_router(
+                None,
+                None,
+                &config.router_config.policy,
+                app_context,
+            )
+            .await
+            {
+                Ok(http_pd) => {
+                    info!("Created HTTP PD router");
+                    manager
+                        .register_router(RouterId::new("http-pd".to_string()), Arc::from(http_pd));
+                }
+                Err(e) => {
+                    warn!("Failed to create HTTP PD router: {e}");
+                }
+            }
+
+            // TODO: Add gRPC routers once we have dynamic tokenizer loading
+
+            info!(
+                "RouterManager initialized with {} routers for multi-router mode",
+                manager.router_count()
+            );
+        } else {
+            info!("Initializing RouterManager in single-router mode");
+
+            let single_router = Arc::from(RouterFactory::create_router(app_context).await?);
+            let router_id = Self::determine_router_id(
+                &config.router_config.mode,
+                &config.router_config.connection_mode,
+            );
+
+            info!("Created single router with ID: {}", router_id.as_str());
+            manager.register_router(router_id.clone(), single_router);
+            manager.set_default_router(router_id);
+        }
+
+        if manager.router_count() == 0 {
+            return Err("No routers could be initialized".to_string());
+        }
+
+        Ok(manager)
+    }
+
+    pub fn determine_router_id(
+        routing_mode: &RoutingMode,
+        connection_mode: &ConnectionMode,
+    ) -> RouterId {
+        match (connection_mode, routing_mode) {
+            (ConnectionMode::Http, RoutingMode::Regular { .. }) => {
+                RouterId::new("http-regular".to_string())
+            }
+            (ConnectionMode::Http, RoutingMode::PrefillDecode { .. }) => {
+                RouterId::new("http-pd".to_string())
+            }
+            (ConnectionMode::Http, RoutingMode::OpenAI { .. }) => {
+                RouterId::new("http-openai".to_string())
+            }
+            (ConnectionMode::Grpc, RoutingMode::Regular { .. }) => {
+                RouterId::new("grpc-regular".to_string())
+            }
+            (ConnectionMode::Grpc, RoutingMode::PrefillDecode { .. }) => {
+                RouterId::new("grpc-pd".to_string())
+            }
+            (ConnectionMode::Grpc, RoutingMode::OpenAI { .. }) => {
+                RouterId::new("grpc-regular".to_string())
+            }
         }
     }
 
-    /// Register a router with the manager
     pub fn register_router(&self, id: RouterId, router: Arc<dyn RouterTrait>) {
         self.routers.insert(id.clone(), router);
 
@@ -69,18 +160,15 @@ impl RouterManager {
         }
     }
 
-    /// Set the default router
     pub fn set_default_router(&self, id: RouterId) {
         let mut default_router = self.default_router.write().unwrap();
         *default_router = Some(id);
     }
 
-    /// Get the number of registered routers
     pub fn router_count(&self) -> usize {
         self.routers.len()
     }
 
-    /// Get router for a specific model based on worker types
     pub fn get_router_for_model(&self, model_id: &str) -> Option<Arc<dyn RouterTrait>> {
         let workers = self.worker_registry.get_by_model(model_id);
 
@@ -111,21 +199,25 @@ impl RouterManager {
         }
     }
 
-    /// Get workers for routing decision
-    pub fn get_workers_for_request(&self, model_id: Option<&str>) -> Vec<Arc<dyn Worker>> {
-        if let Some(model) = model_id {
-            self.worker_registry.get_by_model(model)
-        } else {
-            self.worker_registry.get_all()
-        }
-    }
-
-    /// Get the appropriate router for a request based on headers and request content
     pub fn select_router_for_request(
         &self,
         headers: Option<&HeaderMap>,
         model_id: Option<&str>,
     ) -> Option<Arc<dyn RouterTrait>> {
+        // In single-router mode (enable_igw=false), always use the default router
+        if !self.enable_igw {
+            let default_router = self.default_router.read().unwrap();
+            if let Some(ref default_id) = *default_router {
+                debug!(
+                    "Single-router mode: using default router {} for model {:?}",
+                    default_id.as_str(),
+                    model_id
+                );
+                return self.routers.get(default_id).map(|r| r.clone());
+            }
+        }
+
+        // Multi-router mode logic follows
         let _priority_threshold = headers.and_then(|h| {
             h.get("x-worker-priority")
                 .and_then(|v| v.to_str().ok())
@@ -176,10 +268,6 @@ impl RouterManager {
                 score += 1.0;
             }
 
-            // Get workers for this router and evaluate based on priority/cost
-            // Note: This would require routers to expose their workers or stats
-            // For now, we'll use a simple selection based on router type
-
             // TODO: Once routers expose worker stats, we can evaluate:
             // - Average worker priority vs priority_threshold
             // - Average worker cost vs max_cost
@@ -201,16 +289,11 @@ impl RouterTrait for RouterManager {
         self
     }
 
-    /// Health check - return 503 if no routers available
     async fn health(&self, _req: Request<Body>) -> Response {
-        // Health check should succeed if RouterManager exists, even without routers
-        // Individual router health can be checked via specific endpoints
         (StatusCode::OK, "RouterManager is healthy").into_response()
     }
 
-    /// Health generate - check if any router can handle generate requests
     async fn health_generate(&self, _req: Request<Body>) -> Response {
-        // Return 503 since we have no routers with workers
         // TODO: Should check if any router has healthy workers
         (
             StatusCode::SERVICE_UNAVAILABLE,
@@ -219,10 +302,8 @@ impl RouterTrait for RouterManager {
             .into_response()
     }
 
-    /// Get server information - aggregate from all routers
     async fn get_server_info(&self, _req: Request<Body>) -> Response {
         // TODO: Aggregate info from all routers with healthy workers
-        // For now, return basic info about the RouterManager
         (
             StatusCode::OK,
             serde_json::json!({
@@ -235,9 +316,7 @@ impl RouterTrait for RouterManager {
             .into_response()
     }
 
-    /// Get available models - query from worker registry
     async fn get_models(&self, _req: Request<Body>) -> Response {
-        // Get models from worker registry
         let models = self.worker_registry.get_models();
 
         if models.is_empty() {
@@ -254,10 +333,8 @@ impl RouterTrait for RouterManager {
         }
     }
 
-    /// Get model information
     async fn get_model_info(&self, _req: Request<Body>) -> Response {
         // TODO: Extract model from request and route to appropriate router
-        // For now, return not implemented
         (
             StatusCode::NOT_IMPLEMENTED,
             "Model info endpoint not yet implemented in RouterManager",
@@ -265,22 +342,17 @@ impl RouterTrait for RouterManager {
             .into_response()
     }
 
-    /// Route a generate request
     async fn route_generate(
         &self,
         headers: Option<&HeaderMap>,
         body: &GenerateRequest,
         _model_id: Option<&str>,
     ) -> Response {
-        // Select router based on headers
-        // GenerateRequest doesn't have a model field
         let router = self.select_router_for_request(headers, None);
 
         if let Some(router) = router {
-            // In multi-model mode, pass None since GenerateRequest doesn't have model field
             router.route_generate(headers, body, None).await
         } else {
-            // Return 404 when no router is available for the request
             (
                 StatusCode::NOT_FOUND,
                 "No router available for this request",
@@ -289,7 +361,6 @@ impl RouterTrait for RouterManager {
         }
     }
 
-    /// Route a chat completion request
     async fn route_chat(
         &self,
         headers: Option<&HeaderMap>,
@@ -299,10 +370,8 @@ impl RouterTrait for RouterManager {
         let router = self.select_router_for_request(headers, Some(&body.model));
 
         if let Some(router) = router {
-            // In multi-model mode, pass the model_id to the router
             router.route_chat(headers, body, Some(&body.model)).await
         } else {
-            // Return 404 when the specified model is not found
             (
                 StatusCode::NOT_FOUND,
                 format!("Model '{}' not found or no router available", body.model),
@@ -311,7 +380,6 @@ impl RouterTrait for RouterManager {
         }
     }
 
-    /// Route a completion request
     async fn route_completion(
         &self,
         headers: Option<&HeaderMap>,
@@ -321,12 +389,10 @@ impl RouterTrait for RouterManager {
         let router = self.select_router_for_request(headers, Some(&body.model));
 
         if let Some(router) = router {
-            // In multi-model mode, pass the model_id to the router
             router
                 .route_completion(headers, body, Some(&body.model))
                 .await
         } else {
-            // Return 404 when the specified model is not found
             (
                 StatusCode::NOT_FOUND,
                 format!("Model '{}' not found or no router available", body.model),
@@ -348,26 +414,6 @@ impl RouterTrait for RouterManager {
             .into_response()
     }
 
-    async fn delete_response(&self, _headers: Option<&HeaderMap>, _response_id: &str) -> Response {
-        (
-            StatusCode::NOT_IMPLEMENTED,
-            "responses api not yet implemented in inference gateway mode",
-        )
-            .into_response()
-    }
-
-    async fn list_response_input_items(
-        &self,
-        _headers: Option<&HeaderMap>,
-        _response_id: &str,
-    ) -> Response {
-        (
-            StatusCode::NOT_IMPLEMENTED,
-            "responses api not yet implemented in inference gateway mode",
-        )
-            .into_response()
-    }
-
     async fn get_response(&self, headers: Option<&HeaderMap>, response_id: &str) -> Response {
         let router = self.select_router_for_request(headers, None);
         if let Some(router) = router {
@@ -394,7 +440,26 @@ impl RouterTrait for RouterManager {
         }
     }
 
-    /// Route embeddings request
+    async fn delete_response(&self, _headers: Option<&HeaderMap>, _response_id: &str) -> Response {
+        (
+            StatusCode::NOT_IMPLEMENTED,
+            "responses api not yet implemented in inference gateway mode",
+        )
+            .into_response()
+    }
+
+    async fn list_response_input_items(
+        &self,
+        _headers: Option<&HeaderMap>,
+        _response_id: &str,
+    ) -> Response {
+        (
+            StatusCode::NOT_IMPLEMENTED,
+            "responses api not yet implemented in inference gateway mode",
+        )
+            .into_response()
+    }
+
     async fn route_embeddings(
         &self,
         headers: Option<&HeaderMap>,
@@ -408,7 +473,6 @@ impl RouterTrait for RouterManager {
                 .route_embeddings(headers, body, Some(&body.model))
                 .await
         } else {
-            // Return 404 when the specified model is not found
             (
                 StatusCode::NOT_FOUND,
                 format!("Model '{}' not found or no router available", body.model),
@@ -417,14 +481,12 @@ impl RouterTrait for RouterManager {
         }
     }
 
-    /// Route rerank request
     async fn route_rerank(
         &self,
         headers: Option<&HeaderMap>,
         body: &RerankRequest,
         model_id: Option<&str>,
     ) -> Response {
-        // Try to select a router based on headers
         let router = self.select_router_for_request(headers, None);
 
         if let Some(router) = router {
@@ -438,10 +500,8 @@ impl RouterTrait for RouterManager {
         }
     }
 
-    /// Flush cache on all routers and workers
     async fn flush_cache(&self) -> Response {
         // TODO: Call flush_cache on all routers that have workers
-        // For now, return success if we have any routers
         if self.routers.is_empty() {
             (StatusCode::SERVICE_UNAVAILABLE, "No routers configured").into_response()
         } else {
@@ -450,9 +510,7 @@ impl RouterTrait for RouterManager {
         }
     }
 
-    /// Get worker loads from all routers
     async fn get_worker_loads(&self) -> Response {
-        // Return worker loads from the registry
         let workers = self.worker_registry.get_all();
         let loads: Vec<serde_json::Value> = workers
             .iter()
@@ -476,12 +534,10 @@ impl RouterTrait for RouterManager {
             .into_response()
     }
 
-    /// Get router type name
     fn router_type(&self) -> &'static str {
         "manager"
     }
 
-    /// Server readiness check - check if any router is ready
     fn readiness(&self) -> Response {
         if self.routers.is_empty() {
             (StatusCode::SERVICE_UNAVAILABLE, "No routers configured").into_response()
@@ -492,9 +548,6 @@ impl RouterTrait for RouterManager {
     }
 }
 
-// Note: get_first_available_router removed - we now properly handle
-// router selection based on model and worker availability
-
 impl std::fmt::Debug for RouterManager {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         f.debug_struct("RouterManager")

sgl-router/src/server.rs

@@ -14,10 +14,7 @@ use crate::{
         worker_spec::{WorkerApiResponse, WorkerConfigRequest, WorkerErrorResponse},
     },
     reasoning_parser::ParserFactory,
-    routers::{
+    routers::{router_manager::RouterManager, RouterTrait},
-        router_manager::{RouterId, RouterManager},
-        RouterFactory, RouterTrait,
-    },
     service_discovery::{start_service_discovery, ServiceDiscoveryConfig},
     tokenizer::{factory as tokenizer_factory, traits::Tokenizer},
     tool_parser::ParserRegistry,
@@ -64,10 +61,8 @@ impl AppContext {
         let rate_limit_tokens = rate_limit_tokens_per_second.unwrap_or(max_concurrent_requests);
         let rate_limiter = Arc::new(TokenBucket::new(max_concurrent_requests, rate_limit_tokens));
 
-        // Initialize gRPC-specific components only when in gRPC mode
         let (tokenizer, reasoning_parser_factory, tool_parser_registry) =
             if router_config.connection_mode == ConnectionMode::Grpc {
-                // Get tokenizer path (required for gRPC mode)
                 let tokenizer_path = router_config
                     .tokenizer_path
                     .clone()
@@ -77,7 +72,6 @@ impl AppContext {
                             .to_string()
                     })?;
 
-                // Initialize all gRPC components
                 let tokenizer = Some(
                     tokenizer_factory::create_tokenizer(&tokenizer_path)
                         .map_err(|e| format!("Failed to create tokenizer: {e}"))?,
@@ -87,7 +81,6 @@ impl AppContext {
 
                 (tokenizer, reasoning_parser_factory, tool_parser_registry)
             } else {
-                // HTTP mode doesn't need these components
                 (None, None, None)
             };
 
@@ -96,7 +89,6 @@ impl AppContext {
 
         let router_manager = None;
 
-        // Initialize response storage based on configuration
         let response_storage: SharedResponseStorage = match router_config.history_backend {
             HistoryBackend::Memory => Arc::new(MemoryResponseStorage::new()),
             HistoryBackend::None => Arc::new(NoOpResponseStorage::new()),
@@ -125,12 +117,10 @@ pub struct AppState {
     pub router_manager: Option<Arc<RouterManager>>,
 }
 
-// Fallback handler for unmatched routes
 async fn sink_handler() -> Response {
     StatusCode::NOT_FOUND.into_response()
 }
 
-// Health check endpoints
 async fn liveness(State(state): State<Arc<AppState>>) -> Response {
     state.router.liveness()
 }
@@ -257,7 +247,6 @@ async fn v1_responses_delete(
     Path(response_id): Path<String>,
     headers: http::HeaderMap,
 ) -> Response {
-    // Python server does not support this yet
     state
         .router
         .delete_response(Some(&headers), &response_id)
@@ -269,15 +258,12 @@ async fn v1_responses_list_input_items(
     Path(response_id): Path<String>,
     headers: http::HeaderMap,
 ) -> Response {
-    // Python server does not support this yet
     state
         .router
         .list_response_input_items(Some(&headers), &response_id)
         .await
 }
 
-// ---------- Worker management endpoints (Legacy) ----------
-
 #[derive(Deserialize)]
 struct AddWorkerQuery {
     url: String,
@@ -288,7 +274,6 @@ async fn add_worker(
     State(state): State<Arc<AppState>>,
     Query(AddWorkerQuery { url, api_key }): Query<AddWorkerQuery>,
 ) -> Response {
-    // Use centralized WorkerManager with full context
     let result = WorkerManager::add_worker(&url, &api_key, &state.context).await;
 
     match result {
@@ -298,7 +283,6 @@ async fn add_worker(
 }
 
 async fn list_workers(State(state): State<Arc<AppState>>) -> Response {
-    // Use centralized WorkerManager instead of router's get_worker_urls
     let worker_list = WorkerManager::get_worker_urls(&state.context.worker_registry);
     Json(json!({ "urls": worker_list })).into_response()
 }
@@ -307,7 +291,6 @@ async fn remove_worker(
     State(state): State<Arc<AppState>>,
     Query(AddWorkerQuery { url, .. }): Query<AddWorkerQuery>,
 ) -> Response {
-    // Use centralized WorkerManager with full context
     let result = WorkerManager::remove_worker(&url, &state.context);
 
     match result {
@@ -324,14 +307,10 @@ async fn get_loads(State(state): State<Arc<AppState>>, _req: Request) -> Respons
     state.router.get_worker_loads().await
 }
 
-// ---------- Worker management endpoints (RESTful) ----------
-
-/// POST /workers - Add a new worker with full configuration
 async fn create_worker(
     State(state): State<Arc<AppState>>,
     Json(config): Json<WorkerConfigRequest>,
 ) -> Response {
-    // In single router mode, use centralized WorkerManager with full context
     let result = WorkerManager::add_worker_from_config(&config, &state.context).await;
 
     match result {
@@ -353,9 +332,7 @@ async fn create_worker(
     }
 }
 
-/// GET /workers - List all workers with details
 async fn list_workers_rest(State(state): State<Arc<AppState>>) -> Response {
-    // In single router mode, get detailed worker info from registry
     let workers = state.context.worker_registry.get_all();
     let response = serde_json::json!({
         "workers": workers.iter().map(|worker| {
@@ -374,7 +351,6 @@ async fn list_workers_rest(State(state): State<Arc<AppState>>) -> Response {
                 "cost": worker.cost(),
             });
 
-            // Add bootstrap_port for Prefill workers
             if let WorkerType::Prefill { bootstrap_port } = worker.worker_type() {
                 worker_info["bootstrap_port"] = serde_json::json!(bootstrap_port);
             }
@@ -391,7 +367,6 @@ async fn list_workers_rest(State(state): State<Arc<AppState>>) -> Response {
     Json(response).into_response()
 }
 
-/// GET /workers/{url} - Get specific worker info
 async fn get_worker(State(state): State<Arc<AppState>>, Path(url): Path<String>) -> Response {
     let workers = WorkerManager::get_worker_urls(&state.context.worker_registry);
     if workers.contains(&url) {
@@ -410,9 +385,7 @@ async fn get_worker(State(state): State<Arc<AppState>>, Path(url): Path<String>)
     }
 }
 
-/// DELETE /workers/{url} - Remove a worker
 async fn delete_worker(State(state): State<Arc<AppState>>, Path(url): Path<String>) -> Response {
-    // In single router mode, use centralized WorkerManager with full context
     let result = WorkerManager::remove_worker(&url, &state.context);
 
     match result {
@@ -447,14 +420,12 @@ pub struct ServerConfig {
     pub request_id_headers: Option<Vec<String>>,
 }
 
-/// Build the Axum application with all routes and middleware
 pub fn build_app(
     app_state: Arc<AppState>,
     max_payload_size: usize,
     request_id_headers: Vec<String>,
     cors_allowed_origins: Vec<String>,
 ) -> Router {
-    // Create routes
     let protected_routes = Router::new()
         .route("/generate", post(generate))
         .route("/v1/chat/completions", post(v1_chat_completions))
@@ -494,20 +465,17 @@ pub fn build_app(
         .route("/flush_cache", post(flush_cache))
         .route("/get_loads", get(get_loads));
 
-    // Worker management routes
     let worker_routes = Router::new()
         .route("/workers", post(create_worker))
         .route("/workers", get(list_workers_rest))
         .route("/workers/{url}", get(get_worker))
         .route("/workers/{url}", delete(delete_worker));
 
-    // Build app with all routes and middleware
     Router::new()
         .merge(protected_routes)
         .merge(public_routes)
         .merge(admin_routes)
         .merge(worker_routes)
-        // Request body size limiting
         .layer(tower_http::limit::RequestBodyLimitLayer::new(
             max_payload_size,
         ))
@@ -519,7 +487,6 @@ pub fn build_app(
 }
 
 pub async fn startup(config: ServerConfig) -> Result<(), Box<dyn std::error::Error>> {
-    // Only initialize logging if not already done (for Python bindings support)
     static LOGGING_INITIALIZED: AtomicBool = AtomicBool::new(false);
 
     let _log_guard = if !LOGGING_INITIALIZED.swap(true, Ordering::SeqCst) {
@@ -545,9 +512,8 @@ pub async fn startup(config: ServerConfig) -> Result<(), Box<dyn std::error::Err
         None
     };
 
-    // Initialize prometheus metrics exporter
+    if let Some(prometheus_config) = &config.prometheus_config {
-    if let Some(prometheus_config) = config.prometheus_config {
+        metrics::start_prometheus(prometheus_config.clone());
-        metrics::start_prometheus(prometheus_config);
     }
 
     info!(
@@ -569,7 +535,6 @@ pub async fn startup(config: ServerConfig) -> Result<(), Box<dyn std::error::Err
         .build()
         .expect("Failed to create HTTP client");
 
-    // Create the application context with all dependencies
     let app_context = AppContext::new(
         config.router_config.clone(),
         client.clone(),
@@ -597,67 +562,9 @@ pub async fn startup(config: ServerConfig) -> Result<(), Box<dyn std::error::Err
         worker_stats.total_workers, worker_stats.healthy_workers
     );
 
-    // Create the appropriate router based on enable_igw flag
+    let router_manager = RouterManager::from_config(&config, &app_context).await?;
-    let (router, router_manager): (Arc<dyn RouterTrait>, Option<Arc<RouterManager>>) =
+    let router: Arc<dyn RouterTrait> = router_manager.clone();
-        if config.router_config.enable_igw {
-            info!("Multi-router mode enabled (enable_igw=true)");
 
-            // Create RouterManager with shared registries from AppContext
-            let router_manager = Arc::new(RouterManager::new(app_context.worker_registry.clone()));
-
-            // 1. HTTP Regular Router
-            match RouterFactory::create_regular_router(&app_context).await {
-                Ok(http_regular) => {
-                    info!("Created HTTP Regular router");
-                    router_manager.register_router(
-                        RouterId::new("http-regular".to_string()),
-                        Arc::from(http_regular),
-                    );
-                }
-                Err(e) => {
-                    warn!("Failed to create HTTP Regular router: {e}");
-                }
-            }
-
-            // 2. HTTP PD Router
-            match RouterFactory::create_pd_router(
-                None,
-                None,
-                &config.router_config.policy,
-                &app_context,
-            )
-            .await
-            {
-                Ok(http_pd) => {
-                    info!("Created HTTP PD router");
-                    router_manager
-                        .register_router(RouterId::new("http-pd".to_string()), Arc::from(http_pd));
-                }
-                Err(e) => {
-                    warn!("Failed to create HTTP PD router: {e}");
-                }
-            }
-
-            // TODO: Add gRPC routers once we have dynamic tokenizer loading
-
-            info!(
-                "RouterManager initialized with {} routers",
-                router_manager.router_count()
-            );
-            (
-                router_manager.clone() as Arc<dyn RouterTrait>,
-                Some(router_manager),
-            )
-        } else {
-            info!("Single router mode (enable_igw=false)");
-            // Create single router with the context
-            (
-                Arc::from(RouterFactory::create_router(&app_context).await?),
-                None,
-            )
-        };
-
-    // Start health checker for all workers in the registry
     let _health_checker = app_context
         .worker_registry
         .start_health_checker(config.router_config.health_check.check_interval_secs);
@@ -666,14 +573,12 @@ pub async fn startup(config: ServerConfig) -> Result<(), Box<dyn std::error::Err
         config.router_config.health_check.check_interval_secs
     );
 
-    // Set up concurrency limiter with queue if configured
     let (limiter, processor) = middleware::ConcurrencyLimiter::new(
         app_context.rate_limiter.clone(),
         config.router_config.queue_size,
         Duration::from_secs(config.router_config.queue_timeout_secs),
     );
 
-    // Start queue processor if enabled
     if let Some(processor) = processor {
         spawn(processor.run());
         info!(
@@ -682,21 +587,18 @@ pub async fn startup(config: ServerConfig) -> Result<(), Box<dyn std::error::Err
         );
     }
 
-    // Create app state with router and context
     let app_state = Arc::new(AppState {
         router,
         context: app_context.clone(),
         concurrency_queue_tx: limiter.queue_tx.clone(),
-        router_manager,
+        router_manager: Some(router_manager),
     });
-    // Start the service discovery if enabled
     if let Some(service_discovery_config) = config.service_discovery_config {
         if service_discovery_config.enabled {
             let app_context_arc = Arc::clone(&app_state.context);
             match start_service_discovery(service_discovery_config, app_context_arc).await {
                 Ok(handle) => {
                     info!("Service discovery started");
-                    // Spawn a task to handle the service discovery thread
                     spawn(async move {
                         if let Err(e) = handle.await {
                             error!("Service discovery task failed: {:?}", e);
@@ -725,7 +627,6 @@ pub async fn startup(config: ServerConfig) -> Result<(), Box<dyn std::error::Err
         ]
     });
 
-    // Build the application
     let app = build_app(
         app_state,
         config.max_payload_size,
@@ -744,7 +645,6 @@ pub async fn startup(config: ServerConfig) -> Result<(), Box<dyn std::error::Err
     Ok(())
 }
 
-// Graceful shutdown handler
 async fn shutdown_signal() {
     let ctrl_c = async {
         signal::ctrl_c()
@@ -773,19 +673,16 @@ async fn shutdown_signal() {
     }
 }
 
-// CORS Layer Creation
 fn create_cors_layer(allowed_origins: Vec<String>) -> tower_http::cors::CorsLayer {
     use tower_http::cors::Any;
 
     let cors = if allowed_origins.is_empty() {
-        // Allow all origins if none specified
         tower_http::cors::CorsLayer::new()
             .allow_origin(Any)
             .allow_methods(Any)
             .allow_headers(Any)
             .expose_headers(Any)
     } else {
-        // Restrict to specific origins
         let origins: Vec<http::HeaderValue> = allowed_origins
             .into_iter()
             .filter_map(|origin| origin.parse().ok())