♻️ Use of pydantic to manage config+env variables

FastAPI release has been updated allowing to use lifespan parameter
to prepare/shutdown sub components.

backend/backend/db/db.py

@@ -13,7 +13,7 @@ from sqlalchemy.ext.asyncio import (
 )
 
 from .base_class import Base
-
+from ..settings import DatabaseSettings
 
 logger = getLogger(__name__)
 
@@ -33,9 +33,17 @@ class Database:
         return None
 
     # TODO: Preserve UserLastStopSearchResults table from drop.
-    async def connect(self, db_path: str, clear_static_data: bool = False) -> bool:
+    async def connect(
+        self, settings: DatabaseSettings, clear_static_data: bool = False
+    ) -> bool:
+        password = settings.password
+        path = (
+            f"{settings.driver}://{settings.user}:"
+            f"{password.get_secret_value() if password is not None else ''}"
+            f"@{settings.host}:{settings.port}/{settings.name}"
+        )
         self._async_engine = create_async_engine(
-            db_path, pool_pre_ping=True, pool_size=10, max_overflow=20
+            path, pool_pre_ping=True, pool_size=10, max_overflow=20
         )
 
         if self._async_engine is not None:

backend/backend/settings.py

@@ -0,0 +1,26 @@
+from pydantic import BaseModel, BaseSettings, Field, SecretStr
+
+
+class HttpSettings(BaseModel):
+    host: str = "127.0.0.1"
+    port: int = 8080
+    cert: str | None = None
+
+
+class DatabaseSettings(BaseModel):
+    name: str = "carrramba-encore-rate"
+    host: str = "127.0.0.1"
+    port: int = 5432
+    driver: str = "postgresql+psycopg"
+    user: str = "cer"
+    password: SecretStr | None = None
+
+
+class Settings(BaseSettings):
+    app_name: str
+
+    idfm_api_key: SecretStr = Field(..., env="API_KEY")
+    clear_static_data: bool = Field(..., env="CLEAR_STATIC_DATA")
+
+    http: HttpSettings = HttpSettings()
+    db: DatabaseSettings = DatabaseSettings()

backend/config/config.sample.yaml

@@ -0,0 +1,14 @@
+app_name: carrramba-encore-rate
+
+http:
+  host: 0.0.0.0
+  port: 4443
+  cert: ./config/cert.pem
+
+db:
+  name: carrramba-encore-rate
+  host: 127.0.0.1
+  port: 5432
+  driver: postgresql+psycopg
+  user: cer
+  password: cer_password

backend/main.py

@@ -6,21 +6,18 @@ from os import environ, EX_USAGE
 from typing import Sequence
 
 import uvicorn
+from contextlib import asynccontextmanager
 from fastapi import FastAPI, HTTPException
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.staticfiles import StaticFiles
 from opentelemetry import trace
 from opentelemetry.exporter.otlp.proto.http.trace_exporter import OTLPSpanExporter
+from opentelemetry.instrumentation.fastapi import FastAPIInstrumentor
+from opentelemetry.sdk.resources import Resource, SERVICE_NAME
 from opentelemetry.sdk.trace import TracerProvider
 from opentelemetry.sdk.trace.export import BatchSpanProcessor
-
-from opentelemetry.instrumentation.fastapi import FastAPIInstrumentor
-from opentelemetry.instrumentation.logging import LoggingInstrumentor
-from opentelemetry.sdk.resources import Resource as OtResource
-from opentelemetry.sdk.trace import TracerProvider as OtTracerProvider
-from opentelemetry.sdk.trace.export import BatchSpanProcessor
 from rich import print
-from starlette.types import ASGIApp
+from yaml import safe_load
 
 from backend.db import db
 from backend.idfm_interface import Destinations as IdfmDestinations, IdfmInterface
@@ -34,65 +31,54 @@ from backend.schemas import (
     StopArea as StopAreaSchema,
     StopShape as StopShapeSchema,
 )
-
-API_KEY = environ.get("API_KEY")
-if API_KEY is None:
-    print('No "API_KEY" environment variable set... abort.')
-    exit(EX_USAGE)
-
-APP_NAME = environ.get("APP_NAME", "app")
-MODE = environ.get("MODE", "grpc")
-COLLECTOR_ENDPOINT_GRPC_ENDPOINT = environ.get(
-    "COLLECTOR_ENDPOINT_GRPC_ENDPOINT", "127.0.0.1:14250"  # "jaeger-collector:14250"
-)
-
-# CREATE DATABASE "carrramba-encore-rate";
-# CREATE USER cer WITH ENCRYPTED PASSWORD 'cer_password';
-# GRANT ALL PRIVILEGES ON DATABASE "carrramba-encore-rate" TO cer;
-# \c "carrramba-encore-rate";
-# GRANT ALL ON schema public TO cer;
-# CREATE EXTENSION IF NOT EXISTS pg_trgm;
-
-# TODO: Remove postgresql+psycopg from environ variable
-DB_PATH = "postgresql+psycopg://cer:cer_password@127.0.0.1:5432/carrramba-encore-rate"
+from backend.settings import Settings
 
 
-app = FastAPI()
+CONFIG_PATH = environ.get("CONFIG_PATH", "./config.sample.yaml")
+
+
+def load_settings(path: str) -> Settings:
+    with open(path, "r") as config_file:
+        config = safe_load(config_file)
+
+    return Settings(**config)
+
+
+settings = load_settings(CONFIG_PATH)
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    await db.connect(settings.db, settings.clear_static_data)
+    if settings.clear_static_data:
+        await idfm_interface.startup()
+
+    yield
+
+    await db.disconnect()
+
+
+app = FastAPI(lifespan=lifespan)
+
 app.add_middleware(
     CORSMiddleware,
-    allow_origins=[
-        "https://localhost:4443",
-        "https://localhost:3000",
-    ],
+    allow_origins=["https://localhost:4443", "https://localhost:3000"],
     allow_credentials=True,
     allow_methods=["*"],
     allow_headers=["*"],
 )
 
-trace.set_tracer_provider(TracerProvider())
+app.mount("/widget", StaticFiles(directory="../frontend/", html=True), name="widget")
+
+FastAPIInstrumentor.instrument_app(app)
+
+trace.set_tracer_provider(
+    TracerProvider(resource=Resource.create({SERVICE_NAME: settings.app_name}))
+)
 trace.get_tracer_provider().add_span_processor(BatchSpanProcessor(OTLPSpanExporter()))
-tracer = trace.get_tracer(APP_NAME)
+tracer = trace.get_tracer(settings.app_name)
 
-
-idfm_interface = IdfmInterface(API_KEY, db)
-
-
-# TODO: Add command line argument to force database reset.
-@app.on_event("startup")
-async def startup():
-    await db.connect(DB_PATH, clear_static_data=True)
-    await idfm_interface.startup()
-    # await db.connect(DB_PATH, clear_static_data=False)
-    print("Connected")
-
-
-@app.on_event("shutdown")
-async def shutdown():
-    await db.disconnect()
-
-
-STATIC_ROOT = "../frontend/"
-app.mount("/widget", StaticFiles(directory=STATIC_ROOT, html=True), name="widget")
+idfm_interface = IdfmInterface(settings.idfm_api_key.get_secret_value(), db)
 
 
 def optional_datetime_to_ts(dt: datetime | None) -> int | None:
@@ -281,7 +267,11 @@ async def get_stop_shape(stop_id: int) -> StopShapeSchema | None:
     raise HTTPException(status_code=404, detail=msg)
 
 
-FastAPIInstrumentor.instrument_app(app)
-
 if __name__ == "__main__":
-    uvicorn.run(app, host="0.0.0.0", port=4443, ssl_certfile="./config/cert.pem")
+    http_settings = settings.http
+    uvicorn.run(
+        app,
+        host=http_settings.host,
+        port=http_settings.port,
+        ssl_certfile=http_settings.cert,
+    )

backend/pyproject.toml

@@ -11,7 +11,7 @@ python = "^3.11"
 aiohttp = "^3.8.3"
 rich = "^12.6.0"
 aiofiles = "^22.1.0"
-fastapi = "^0.88.0"
+fastapi = "^0.95.0"
 uvicorn = "^0.20.0"
 msgspec = "^0.12.0"
 pyshp = "^2.3.1"
@@ -25,6 +25,7 @@ opentelemetry-exporter-otlp-proto-http = "^1.17.0"
 opentelemetry-instrumentation-sqlalchemy = "^0.38b0"
 sqlalchemy = "^2.0.12"
 psycopg = "^3.1.9"
+pyyaml = "^6.0"
 
 [build-system]
 requires = ["poetry-core"]
@@ -48,6 +49,7 @@ yapf = "^0.32.0"
 whatthepatch = "^1.0.4"
 mypy = "^1.0.0"
 types-sqlalchemy-utils = "^1.0.1"
+types-pyyaml = "^6.0.12.9"
 
 [tool.mypy]
 plugins = "sqlalchemy.ext.mypy.plugin"