Merge pull request #2 from NicholasGoh/feat/fastapi-boilerplate

Feat/fastapi boilerplate

Author: NicholasGoh

.devcontainer/devcontainer.json

@@ -6,7 +6,7 @@
 	"dockerComposeFile": [
 		"../compose-dev.yaml"
 	],
-	"service": "backend",
+	"service": "api",
 	"workspaceFolder": "/app",
 	"customizations": {
 		"vscode": {
@@ -39,6 +39,7 @@
 				"editor.formatOnSave": true,
 				"files.insertFinalNewline": true,
 				"files.trimFinalNewlines": true,
+				"python.venvPath": "/app/.venv/bin/python",
 				"[python]": {
 					"editor.formatOnSave": true,
 					"editor.codeActionsOnSave": {

backend/Dockerfile

@@ -0,0 +1,19 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "name": "Python Debugger: FastAPI",
+            "type": "debugpy",
+            "request": "launch",
+            "module": "fastapi",
+            "args": [
+                "run",
+                "api/main.py",
+                "--reload"
+            ]
+        }
+    ]
+}

backend/api/.vscode/launch.json

@@ -0,0 +1,11 @@
+FROM ghcr.io/astral-sh/uv:python3.13-bookworm
+
+WORKDIR /app
+COPY ./backend/api/uv.lock ./backend/api/pyproject.toml ./
+RUN uv sync --frozen
+RUN apt-get update && apt-get install -y --no-install-recommends curl
+COPY ./envs/backend.env /opt/.env
+COPY ./backend/api /app/api
+COPY ./backend/shared_mcp /app/shared_mcp
+ENV PYTHONPATH /app:$PYTHONPATH
+ENTRYPOINT ["uv", "run", "fastapi", "run", "api/main.py"]

backend/api/Dockerfile

@@ -0,0 +1,20 @@
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    model_config = SettingsConfigDict(
+        env_file="/opt/.env",
+        env_ignore_empty=True,
+        extra="ignore",
+    )
+
+    model: str = "gpt-4o-mini-2024-07-18"
+    openai_api_key: str = ""
+    mcp_server_port: int = 8050
+
+    pg_url: str = "postgres://postgres"
+    pg_user: str = "postgres"
+    pg_pass: str = "postgres"
+
+
+settings = Settings()

backend/api/config.py

@@ -0,0 +1,23 @@
+from typing import Annotated, Iterable
+
+from config import settings
+from fastapi import Depends
+from langchain_openai import ChatOpenAI
+
+
+def llm_factory() -> ChatOpenAI:
+    llm = ChatOpenAI(
+        streaming=True,
+        model=settings.model,
+        temperature=0,
+        api_key=settings.openai_api_key,
+        stream_usage=True,
+    )
+    return llm
+
+
+def get_llm_session() -> Iterable[ChatOpenAI]:
+    yield llm_factory()
+
+
+LLMDep = Annotated[ChatOpenAI, Depends(get_llm_session)]

backend/api/dependencies.py

@@ -0,0 +1,7 @@
+from fastapi import FastAPI
+
+from api.routers import llms, mcps
+
+app = FastAPI(swagger_ui_parameters={"tryItOutEnabled": True})
+app.include_router(llms.router, prefix="/v1")
+app.include_router(mcps.router, prefix="/v1")

backend/api/main.py

@@ -1,5 +1,5 @@
 [project]
-name = "app"
+name = "api"
 version = "0.1.0"
 description = "Add your description here"
 readme = "README.md"
@@ -14,6 +14,7 @@ dependencies = [
     "langchain-postgres==0.0.12",
     "langfuse==2.60.2",
     "langgraph==0.2.39",
+    "mcp[cli]>=1.6.0",
     "prometheus-client==0.21.1",
     "psycopg[binary]==3.2.3",
     "pydantic-settings==2.6.0",

backend/pyproject.toml renamed to backend/api/pyproject.toml

@@ -0,0 +1,22 @@
+from typing import AsyncGenerator
+
+from fastapi import APIRouter
+from sse_starlette.sse import EventSourceResponse
+from starlette.responses import Response
+
+from api.dependencies import LLMDep
+
+router = APIRouter(tags=["chat"])
+
+
+async def stream(
+    query: str, llm: LLMDep
+) -> AsyncGenerator[dict[str, str], None]:
+    async for chunk in llm.astream_events(query):
+        yield dict(data=chunk)
+
+
+@router.get("/chat/completions")
+async def completions(query: str, llm: LLMDep) -> Response:
+    """Stream completions via Server Sent Events"""
+    return EventSourceResponse(stream(query, llm))

backend/api/routers/llms.py

@@ -0,0 +1,51 @@
+from contextlib import asynccontextmanager
+from typing import Iterable
+
+from config import settings
+from fastapi import APIRouter
+from mcp import ClientSession, types
+from mcp.client.sse import sse_client
+
+from shared_mcp.models import ToolRequest
+
+router = APIRouter(prefix="/mcps", tags=["mcps"])
+
+
+@asynccontextmanager
+async def mcp_sse_client():
+    async with sse_client(f"http://mcp:{settings.mcp_server_port}/sse") as (
+        read_stream,
+        write_stream,
+    ):
+        async with ClientSession(read_stream, write_stream) as session:
+            await session.initialize()
+            yield session
+
+
+@router.get("/list-tools")
+async def list_tools() -> Iterable[types.Tool]:
+    """
+    Lists tools available from MCP server
+
+    This endpoint establishes a Server-Sent Events connection with the client
+    and forwards communication to the Model Context Protocol server.
+    """
+    async with mcp_sse_client() as session:
+        response = await session.list_tools()
+        return response.tools
+
+
+@router.post("/call-tool")
+async def call_tool(request: ToolRequest) -> str:
+    """
+    Calls tool available from MCP server
+
+    This endpoint establishes a Server-Sent Events connection with the client
+    and forwards communication to the Model Context Protocol server.
+    """
+    async with mcp_sse_client() as session:
+        response = await session.call_tool(
+            request.tool_name,
+            arguments=request.model_dump(exclude=["tool_name"]),
+        )
+        return response.content[0].text