Version 0.4.0

Changes:
- put ObservabilityMiddleware before ExceptionHandlerMiddleware to avoid repetative code
- add application startup and last metrics update metrics along with CPU usage metric and threads count
- move host and port to new uvicorn section at config along with new reload and forwarded_allow_ips
- add request_id and remove trace_id/span_id generation if tracing is disabled
- move logging logic from utils to observability
- pass trace_id/span_id in HEX form

{{project_slug}}/fastapi_init.py.jinja

@@ -2,8 +2,9 @@
 
 import os
 from contextlib import asynccontextmanager
+from typing import NoReturn
 
-from fastapi import FastAPI
+from fastapi import FastAPI, Request
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.middleware.gzip import GZipMiddleware
 from fastapi.openapi.docs import get_swagger_ui_html
@@ -14,30 +15,17 @@ from {{project_slug}}.db.connection.manager import PostgresConnectionManager
 from {{project_slug}}.dependencies import connection_manager_dep, logger_dep, metrics_dep
 from {{project_slug}}.exceptions.mapper import ExceptionMapper
 from {{project_slug}}.handlers.debug import DebugException, DebugExceptionWithParams
-from {{project_slug}}.middlewares.exception_handler import ExceptionHandlerMiddleware
+from {{project_slug}}.middlewares.exception_handler import ExceptionHandlerMiddleware, HandlerNotFoundError
 from {{project_slug}}.middlewares.observability import ObservabilityMiddleware
-from {{project_slug}}.observability.metrics import init_metrics
+from {{project_slug}}.observability.logging import configure_logging
+from {{project_slug}}.observability.metrics import setup_metrics
 from {{project_slug}}.observability.otel_agent import OpenTelemetryAgent
-from {{project_slug}}.utils.observability import URLsMapper, configure_logging
+from {{project_slug}}.observability.utils import URLsMapper
 
 from .handlers import list_of_routers
 from .version import LAST_UPDATE, VERSION
 
 
-def _get_exception_mapper(debug: bool) -> ExceptionMapper:
-    mapper = ExceptionMapper()
-    if debug:
-        mapper.register_simple(DebugException, 506, "That's how a debug exception look like")
-        mapper.register_func(
-            DebugExceptionWithParams,
-            lambda exc: JSONResponse(
-                {"error": "That's how a debug exception with params look like", "message": exc.message},
-                status_code=exc.status_code,
-            ),
-        )
-    return mapper
-
-
 def bind_routes(application: FastAPI, prefix: str, debug: bool) -> None:
     """Bind all routes to application."""
     for router in list_of_routers:
@@ -84,6 +72,10 @@ def get_app(prefix: str = "/api") -> FastAPI:
             swagger_css_url="https://unpkg.com/swagger-ui-dist@5.11.7/swagger-ui.css",
         )
 
+    @application.exception_handler(404)
+    async def handle_404(request: Request, exc: Exception) -> NoReturn:
+        raise HandlerNotFoundError() from exc
+
     application.add_middleware(
         CORSMiddleware,
         allow_origins=app_config.app.cors.allow_origins,
@@ -99,30 +91,34 @@ def get_app(prefix: str = "/api") -> FastAPI:
         app_config.observability.logging,
         tracing_enabled=app_config.observability.jaeger is not None,
     )
-    metrics = init_metrics()
-    exception_mapper = _get_exception_mapper(app_config.app.debug)
+    metrics = setup_metrics()
+
+    exception_mapper = ExceptionMapper()
+    _register_exceptions(exception_mapper, debug=app_config.app.debug)
     connection_manager = PostgresConnectionManager(
         master=app_config.db.master,
         replicas=app_config.db.replicas,
         logger=logger,
         application_name=f"{{project_slug}}_{VERSION}",
     )
-    urls_mapper = URLsMapper(app_config.observability.prometheus.urls_mapping)
+    urls_mapper = URLsMapper()
+    urls_mapper.add_routes(application.routes)
 
     connection_manager_dep.init_dispencer(application, connection_manager)
     metrics_dep.init_dispencer(application, metrics)
     logger_dep.init_dispencer(application, logger)
 
     application.add_middleware(
-        ObservabilityMiddleware,
+        ExceptionHandlerMiddleware,
+        debug=app_config.app.debug,
         exception_mapper=exception_mapper,
-        metrics=metrics,
         urls_mapper=urls_mapper,
+        errors_metric=metrics.http.errors,
     )
     application.add_middleware(
-        ExceptionHandlerMiddleware,
-        debug=[app_config.app.debug],
-        exception_mapper=exception_mapper,
+        ObservabilityMiddleware,
+        metrics=metrics,
+        urls_mapper=urls_mapper,
     )
 
     return application
@@ -135,13 +131,9 @@ async def lifespan(application: FastAPI):
     Initializes database connection in pass_services_dependencies middleware.
     """
     app_config: {{ProjectName}}Config = application.state.config
-    logger = logger_dep.obtain(application)
+    logger = logger_dep.from_app(application)
 
-    await logger.ainfo("application is being configured", config=app_config.to_order_dict())
-
-    for middleware in application.user_middleware:
-        if middleware.cls == ExceptionHandlerMiddleware:
-            middleware.kwargs["debug"][0] = app_config.app.debug
+    await logger.ainfo("application is starting", config=app_config.to_order_dict())
 
     otel_agent = OpenTelemetryAgent(
         app_config.observability.prometheus,
@@ -153,4 +145,17 @@ async def lifespan(application: FastAPI):
     otel_agent.shutdown()
 
 
+def _register_exceptions(mapper: ExceptionMapper, debug: bool) -> None:
+    if debug:
+        mapper.register_simple(DebugException, 506, "That's how a debug exception look like")
+        mapper.register_func(
+            DebugExceptionWithParams,
+            lambda exc: JSONResponse(
+                {"error": "That's how a debug exception with params look like", "message": exc.message},
+                status_code=exc.status_code,
+            ),
+        )
+    return mapper
+
+
 app = get_app()