feat: add param --instruct-model, allowing specify different model for q&a use cases. (#494)

crates/tabby/src/serve/engine.rs

@@ -18,15 +18,17 @@ fn get_param(params: &Value, key: &str) -> String {
         .to_string()
 }
 
-pub fn create_engine(args: &crate::serve::ServeArgs) -> (Box<dyn TextGeneration>, Option<String>) {
+pub fn create_engine(
+    model: &str,
+    args: &crate::serve::ServeArgs,
+) -> (Box<dyn TextGeneration>, Option<String>) {
     if args.device != super::Device::ExperimentalHttp {
-        let model_dir = get_model_dir(&args.model);
+        let model_dir = get_model_dir(model);
         let metadata = read_metadata(&model_dir);
         let engine = create_local_engine(args, &model_dir, &metadata);
         (engine, metadata.prompt_template)
     } else {
-        let params: Value =
-            serdeconv::from_json_str(&args.model).expect("Failed to parse model string");
+        let params: Value = serdeconv::from_json_str(model).expect("Failed to parse model string");
 
         let kind = get_param(&params, "kind");
 

crates/tabby/src/serve/health.rs

@@ -10,6 +10,8 @@ use utoipa::ToSchema;
 #[derive(Serialize, Deserialize, ToSchema, Clone, Debug)]
 pub struct HealthState {
     model: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    instruct_model: Option<String>,
     device: String,
     compute_type: String,
     arch: String,
@@ -30,6 +32,7 @@ impl HealthState {
 
         Self {
             model: args.model.clone(),
+            instruct_model: args.instruct_model.clone(),
             device: args.device.to_string(),
             compute_type: args.compute_type.to_string(),
             arch: ARCH.to_string(),

crates/tabby/src/serve/mod.rs

@@ -105,10 +105,15 @@ pub enum ComputeType {
 
 #[derive(Args)]
 pub struct ServeArgs {
-    /// Model id for serving.
+    /// Model id for `/completion` API endpoint.
     #[clap(long)]
     model: String,
 
+    /// Model id for `/generate` and `/generate_stream` API endpoints.
+    /// If not set, `model` will be loaded for the purpose.
+    #[clap(long)]
+    instruct_model: Option<String>,
+
     #[clap(long, default_value_t = 8080)]
     port: u16,
 
@@ -142,16 +147,11 @@ fn should_download_ggml_files(device: &Device) -> bool {
 pub async fn main(config: &Config, args: &ServeArgs) {
     valid_args(args);
 
-    let downloader = Downloader::new(&args.model, /* prefer_local_file= */ true);
     if args.device != Device::ExperimentalHttp {
-        let handler = |err| fatal!("Failed to fetch model '{}' due to '{}'", args.model, err,);
-        let download_result = if should_download_ggml_files(&args.device) {
-            downloader.download_ggml_files().await
-        } else {
-            downloader.download_ctranslate2_files().await
-        };
-
-        download_result.unwrap_or_else(handler);
+        download_model(&args.model, &args.device).await;
+        if let Some(instruct_model) = &args.instruct_model {
+            download_model(instruct_model, &args.device).await;
+        }
     } else {
         warn!("HTTP device is unstable and does not comply with semver expectations.")
     }
@@ -177,8 +177,14 @@ pub async fn main(config: &Config, args: &ServeArgs) {
 }
 
 fn api_router(args: &ServeArgs, config: &Config) -> Router {
-    let (engine, prompt_template) = create_engine(args);
+    let (engine, prompt_template) = create_engine(&args.model, args);
     let engine = Arc::new(engine);
+    let instruct_engine = if let Some(instruct_model) = &args.instruct_model {
+        Arc::new(create_engine(instruct_model, args).0)
+    } else {
+        engine.clone()
+    };
+
     Router::new()
         .route("/v1/events", routing::post(events::log_event))
         .route(
@@ -193,13 +199,15 @@ fn api_router(args: &ServeArgs, config: &Config) -> Router {
         )
         .route(
             "/v1beta/generate",
-            routing::post(generate::generate)
-                .with_state(Arc::new(generate::GenerateState::new(engine.clone()))),
+            routing::post(generate::generate).with_state(Arc::new(generate::GenerateState::new(
+                instruct_engine.clone(),
+            ))),
         )
         .route(
             "/v1beta/generate_stream",
-            routing::post(generate::generate_stream)
-                .with_state(Arc::new(generate::GenerateState::new(engine.clone()))),
+            routing::post(generate::generate_stream).with_state(Arc::new(
+                generate::GenerateState::new(instruct_engine.clone()),
+            )),
         )
         .layer(CorsLayer::permissive())
         .layer(opentelemetry_tracing_layer())
@@ -272,3 +280,15 @@ fn add_proxy_server(
 
     doc
 }
+
+async fn download_model(model: &str, device: &Device) {
+    let downloader = Downloader::new(model, /* prefer_local_file= */ true);
+    let handler = |err| fatal!("Failed to fetch model '{}' due to '{}'", model, err,);
+    let download_result = if should_download_ggml_files(device) {
+        downloader.download_ggml_files().await
+    } else {
+        downloader.download_ctranslate2_files().await
+    };
+
+    download_result.unwrap_or_else(handler);
+}