feat: serve all LLMs as OpenAI-compatible API (#431)

1 files changed, 364 insertions, 0 deletions

diff --git a/src/serve.rs b/src/serve.rs
new file mode 100644
index 0000000..2286b61
--- /dev/null
+++ b/src/serve.rs
@@ -0,0 +1,364 @@
+use crate::{
+    client::{init_client, ClientConfig, Message, Model, ReplyEvent, ReplyHandler, SendData},
+    config::{Config, GlobalConfig},
+    utils::create_abort_signal,
+};
+
+use anyhow::{anyhow, bail, Result};
+use bytes::Bytes;
+use chrono::{Timelike, Utc};
+use futures_util::StreamExt;
+use http::{Method, Response, StatusCode};
+use http_body_util::{combinators::BoxBody, BodyExt, Full, StreamBody};
+use hyper::{
+    body::{Frame, Incoming},
+    service::service_fn,
+};
+use hyper_util::rt::{TokioExecutor, TokioIo};
+use parking_lot::RwLock;
+use serde::Deserialize;
+use serde_json::{json, Value};
+use std::{convert::Infallible, sync::Arc};
+use tokio::{
+    net::TcpListener,
+    sync::{
+        mpsc::{unbounded_channel, UnboundedReceiver, UnboundedSender},
+        oneshot,
+    },
+};
+use tokio_graceful::Shutdown;
+use tokio_stream::wrappers::UnboundedReceiverStream;
+
+const DEFAULT_ADDRESS: &str = "0.0.0.0:8080";
+
+type AppResponse = Response<BoxBody<Bytes, Infallible>>;
+
+pub async fn run(config: GlobalConfig, addr: Option<String>) -> Result<()> {
+    let addr = match addr {
+        Some(addr) => {
+            if let Ok(port) = addr.parse::<u16>() {
+                format!("0.0.0.0:{port}")
+            } else {
+                addr
+            }
+        }
+        None => DEFAULT_ADDRESS.to_string(),
+    };
+    let clients = config.read().clients.clone();
+    let model = config.read().model.clone();
+    let listener = TcpListener::bind(&addr).await?;
+    let server = Arc::new(Server { clients, model });
+    let stop_server = server.run(listener).await?;
+    println!("Access the chat completion API at: http://{addr}/v1/chat/completions");
+    shutdown_signal().await;
+    let _ = stop_server.send(());
+    Ok(())
+}
+
+struct Server {
+    clients: Vec<ClientConfig>,
+    model: Model,
+}
+
+impl Server {
+    async fn run(self: Arc<Self>, listener: TcpListener) -> Result<oneshot::Sender<()>> {
+        let (tx, rx) = oneshot::channel();
+        tokio::spawn(async move {
+            let shutdown = Shutdown::new(async { rx.await.unwrap_or_default() });
+            let guard = shutdown.guard_weak();
+
+            loop {
+                tokio::select! {
+                    res = listener.accept() => {
+                        let Ok((cnx, _)) = res else {
+                            continue;
+                        };
+
+                        let stream = TokioIo::new(cnx);
+                        let server = self.clone();
+                        shutdown.spawn_task(async move {
+                            let hyper_service = service_fn(move |request: hyper::Request<Incoming>| {
+                                server.clone().handle(request)
+                            });
+                            let _ = hyper_util::server::conn::auto::Builder::new(TokioExecutor::new())
+                                .serve_connection_with_upgrades(stream, hyper_service)
+                                .await;
+                        });
+                    }
+                    _ = guard.cancelled() => {
+                        break;
+                    }
+                }
+            }
+        });
+        Ok(tx)
+    }
+
+    async fn handle(
+        self: Arc<Self>,
+        req: hyper::Request<Incoming>,
+    ) -> std::result::Result<AppResponse, hyper::Error> {
+        let method = req.method().clone();
+        let uri = req.uri().clone();
+        let mut status = StatusCode::OK;
+        let res = if method == Method::POST && uri == "/v1/chat/completions" {
+            self.chat_completion(req).await
+        } else if method == Method::OPTIONS && uri == "/v1/chat/completions" {
+            status = StatusCode::NO_CONTENT;
+            Ok(Response::default())
+        } else {
+            status = StatusCode::NOT_FOUND;
+            Err(anyhow!("The requested endpoint was not found."))
+        };
+        let mut res = match res {
+            Ok(res) => {
+                info!("{method} {uri} {}", status.as_u16());
+                res
+            }
+            Err(err) => {
+                error!("{method} {uri} {} {err}", status.as_u16());
+                ret_err(err)
+            }
+        };
+        *res.status_mut() = status;
+        set_cors_header(&mut res);
+        Ok(res)
+    }
+
+    async fn chat_completion(&self, req: hyper::Request<Incoming>) -> Result<AppResponse> {
+        let req_body = req.collect().await?.to_bytes();
+        let req_body: ChatCompletionReqBody = serde_json::from_slice(&req_body)
+            .map_err(|err| anyhow!("Invalid request body, {err}"))?;
+
+        let ChatCompletionReqBody {
+            model,
+            messages,
+            temperature,
+            max_tokens,
+            stream,
+        } = req_body;
+
+        let config = Config {
+            clients: self.clients.to_vec(),
+            model: self.model.clone(),
+            ..Default::default()
+        };
+        let config = Arc::new(RwLock::new(config));
+        if model != "default" && model != self.model.id() {
+            config.write().set_model(&model)?;
+        }
+
+        let mut client = init_client(&config)?;
+        if max_tokens.is_some() {
+            client.set_model(client.model().clone().set_max_output_tokens(max_tokens));
+        }
+        let abort = create_abort_signal();
+        let http_client = client.build_client()?;
+
+        let completion_id = generate_completion_id();
+        let created = Utc::now().timestamp();
+
+        let send_data: SendData = SendData {
+            messages,
+            temperature,
+            stream,
+        };
+
+        if stream {
+            let (tx, mut rx) = unbounded_channel();
+            tokio::spawn(async move {
+                let mut is_first = true;
+                let (tx2, rx2) = unbounded_channel();
+                let mut handler = ReplyHandler::new(tx2, abort);
+                async fn map_event(
+                    mut rx: UnboundedReceiver<ReplyEvent>,
+                    tx: &UnboundedSender<ResEvent>,
+                    is_first: &mut bool,
+                ) {
+                    while let Some(reply_event) = rx.recv().await {
+                        if *is_first {
+                            let _ = tx.send(ResEvent::First(None));
+                            *is_first = false;
+                        }
+                        match reply_event {
+                            ReplyEvent::Text(text) => {
+                                let _ = tx.send(ResEvent::Text(text));
+                            }
+                            ReplyEvent::Done => {
+                                let _ = tx.send(ResEvent::Done);
+                            }
+                        }
+                    }
+                }
+                tokio::select! {
+                    _ = map_event(rx2, &tx, &mut is_first) => {}
+                    ret = client.send_message_streaming_inner(&http_client, &mut handler, send_data) => {
+                        if let Err(err) = ret {
+                            send_first_event(&tx, Some(format!("{err:?}")), &mut is_first)
+                        }
+                    }
+                }
+            });
+
+            let first_event = rx.recv().await;
+
+            if let Some(ResEvent::First(Some(err))) = first_event {
+                bail!("{err}");
+            }
+
+            let shared: Arc<(String, i64)> = Arc::new((completion_id, created));
+            let stream = UnboundedReceiverStream::new(rx);
+            let stream = stream.filter_map(move |res_event| {
+                let shared = shared.clone();
+                async move {
+                    match res_event {
+                        ResEvent::Text(text) => {
+                            Some(Ok(create_frame(&shared.0, shared.1, &text, false)))
+                        }
+                        ResEvent::Done => Some(Ok(create_frame(&shared.0, shared.1, "", true))),
+                        _ => None,
+                    }
+                }
+            });
+            let res = Response::builder()
+                .status(StatusCode::OK)
+                .header("Content-Type", "text/event-stream")
+                .header("Cache-Control", "no-cache")
+                .header("Connection", "keep-alive")
+                .body(BodyExt::boxed(StreamBody::new(stream)))?;
+            Ok(res)
+        } else {
+            let content = client.send_message_inner(&http_client, send_data).await?;
+            let res = Response::builder()
+                .header("Content-Type", "application/json")
+                .body(Full::new(ret_non_stream(&completion_id, created, &content)).boxed())?;
+            Ok(res)
+        }
+    }
+}
+
+#[derive(Debug, Deserialize)]
+struct ChatCompletionReqBody {
+    model: String,
+    messages: Vec<Message>,
+    temperature: Option<f64>,
+    max_tokens: Option<isize>,
+    #[serde(default)]
+    stream: bool,
+}
+
+#[derive(Debug)]
+enum ResEvent {
+    First(Option<String>),
+    Text(String),
+    Done,
+}
+
+fn send_first_event(tx: &UnboundedSender<ResEvent>, data: Option<String>, is_first: &mut bool) {
+    if *is_first {
+        let _ = tx.send(ResEvent::First(data));
+        *is_first = false;
+    }
+}
+
+async fn shutdown_signal() {
+    tokio::signal::ctrl_c()
+        .await
+        .expect("Failed to install CTRL+C signal handler")
+}
+
+fn generate_completion_id() -> String {
+    let random_id = chrono::Utc::now().nanosecond();
+    format!("chatcmpl-{}", random_id)
+}
+
+fn set_cors_header(res: &mut AppResponse) {
+    res.headers_mut().insert(
+        hyper::header::ACCESS_CONTROL_ALLOW_ORIGIN,
+        hyper::header::HeaderValue::from_static("*"),
+    );
+    res.headers_mut().insert(
+        hyper::header::ACCESS_CONTROL_ALLOW_METHODS,
+        hyper::header::HeaderValue::from_static("GET,POST,PUT,PATCH,DELETE"),
+    );
+    res.headers_mut().insert(
+        hyper::header::ACCESS_CONTROL_ALLOW_HEADERS,
+        hyper::header::HeaderValue::from_static("Content-Type,Authorization"),
+    );
+}
+
+fn create_frame(id: &str, created: i64, content: &str, done: bool) -> Frame<Bytes> {
+    let (delta, finish_reason) = if done {
+        (json!({}), "stop".into())
+    } else {
+        let delta = if content.is_empty() {
+            json!({ "role": "assistant", "content": content })
+        } else {
+            json!({ "content": content })
+        };
+        (delta, Value::Null)
+    };
+    let mut value = json!({
+        "id": id,
+        "object": "chat.completion.chunk",
+        "created": created,
+        "model": "gpt-3.5-turbo",
+        "choices": [
+            {
+                "index": 0,
+                "delta": delta,
+                "finish_reason": finish_reason,
+            },
+        ],
+    });
+    let output = if done {
+        value["usage"] = json!({
+            "prompt_tokens": 0,
+            "completion_tokens": 0,
+            "total_tokens": 0,
+        });
+        format!("data: {value}\n\ndata: [DONE]\n\n")
+    } else {
+        format!("data: {value}\n\n")
+    };
+    Frame::data(Bytes::from(output))
+}
+
+fn ret_non_stream(id: &str, created: i64, content: &str) -> Bytes {
+    let res_body = json!({
+        "id": id,
+        "object": "chat.completion",
+        "created": created,
+        "model": "gpt-3.5-turbo",
+        "choices": [
+            {
+                "index": 0,
+                "message": {
+                    "role": "assistant",
+                    "content": content,
+                },
+                "finish_reason": "stop",
+            },
+        ],
+        "usage": {
+            "prompt_tokens": 0,
+            "completion_tokens": 0,
+            "total_tokens": 0,
+        },
+    });
+    Bytes::from(res_body.to_string())
+}
+
+fn ret_err<T: std::fmt::Display>(err: T) -> AppResponse {
+    let data = json!({
+        "error": {
+            "message": err.to_string(),
+            "type": "invalid_request_error",
+        },
+    });
+    Response::builder()
+        .status(StatusCode::OK)
+        .header("Content-Type", "application/json")
+        .body(Full::new(Bytes::from(data.to_string())).boxed())
+        .unwrap()
+}