Initial commit

This is a FastAPI backend microservice template used with `copier` utility.

Features of applied template are:
- Configuration file processing logic
- Metrics and tracing (both optional) configuration available
- Debug endpoints
- Database migration commands, prepared Alembic environment
- Database usage example in ping_db endpoint
- gitea sanity check pipeline

{{project_slug}}/exceptions/__init__.py.jinja

@@ -0,0 +1,5 @@
+from .base import {{ProjectName}}Error
+
+__all__ = [
+    "{{ProjectName}}Error",
+]

{{project_slug}}/exceptions/base.py.jinja

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+"""Base application exception class is defined here."""
+
+
+class {{ProjectName}}Error(RuntimeError):
+    """
+    Base application exception to inherit from.
+    """
+
+    def __str__(self) -> str:
+        return "Unexpected error happened in {{project_name}}"

{{project_slug}}/exceptions/mapper.py

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+"""Mapper from exceptions to HTTP responses is defined here"""
+
+from typing import Callable, Type
+
+from fastapi import HTTPException
+from fastapi.responses import JSONResponse
+
+
+class ExceptionMapper:
+    def __init__(self):
+        self._known_exceptions: dict[Type, Callable[[Exception], JSONResponse]] = {}
+
+    def register_simple(self, exception_type: Type, status_code: int, detail: str) -> None:
+        self._known_exceptions[exception_type] = lambda _: JSONResponse(
+            {"code": status_code, "detail": detail}, status_code=status_code
+        )
+
+    def register_func(self, exception_type: Type, func: Callable[[Exception], JSONResponse]) -> None:
+        self._known_exceptions[exception_type] = func
+
+    def is_known(self, exc: Exception) -> bool:
+        return type(exc) in self._known_exceptions or isinstance(exc, HTTPException)
+
+    def apply(self, exc: Exception) -> JSONResponse:
+        if (res := self.apply_if_known(exc)) is not None:
+            return res
+        return JSONResponse({"code": 500, "detail": "unhandled exception"}, status_code=500)
+
+    def apply_if_known(self, exc: Exception) -> JSONResponse | None:
+        if isinstance(exc, HTTPException):
+            return JSONResponse({"code": exc.status_code, "detail": exc.detail}, status_code=exc.status_code)
+        if (t := type(exc)) in self._known_exceptions:
+            return self._known_exceptions[t](exc)
+        return None