feat: project skeleton

- infra (k8s, kind, helm, docker) backbone is implemented
- security: implementation + unit tests are done

app/db.py

@@ -0,0 +1,80 @@
+"""Database connection management using asyncpg."""
+
+from collections.abc import AsyncGenerator
+from contextlib import asynccontextmanager
+
+import asyncpg
+import redis.asyncio as redis
+
+
+class Database:
+    """Manages asyncpg connection pool."""
+
+    pool: asyncpg.Pool | None = None
+
+    async def connect(self, dsn: str) -> None:
+        """Create connection pool."""
+        self.pool = await asyncpg.create_pool(
+            dsn,
+            min_size=5,
+            max_size=20,
+            command_timeout=60,
+        )
+
+    async def disconnect(self) -> None:
+        """Close connection pool."""
+        if self.pool:
+            await self.pool.close()
+
+    @asynccontextmanager
+    async def connection(self) -> AsyncGenerator[asyncpg.Connection, None]:
+        """Acquire a connection from the pool."""
+        if not self.pool:
+            raise RuntimeError("Database not connected")
+        async with self.pool.acquire() as conn:
+            yield conn
+
+    @asynccontextmanager
+    async def transaction(self) -> AsyncGenerator[asyncpg.Connection, None]:
+        """Acquire a connection with an active transaction."""
+        if not self.pool:
+            raise RuntimeError("Database not connected")
+        async with self.pool.acquire() as conn:
+            async with conn.transaction():
+                yield conn
+
+
+class RedisClient:
+    """Manages Redis connection."""
+
+    client: redis.Redis | None = None
+
+    async def connect(self, url: str) -> None:
+        """Create Redis connection."""
+        self.client = redis.from_url(url, decode_responses=True)
+
+    async def disconnect(self) -> None:
+        """Close Redis connection."""
+        if self.client:
+            await self.client.aclose()
+
+    async def ping(self) -> bool:
+        """Check if Redis is reachable."""
+        if not self.client:
+            return False
+        try:
+            await self.client.ping()
+            return True
+        except redis.RedisError:
+            return False
+
+
+# Global instances
+db = Database()
+redis_client = RedisClient()
+
+
+async def get_conn() -> AsyncGenerator[asyncpg.Connection, None]:
+    """Dependency for getting a database connection."""
+    async with db.connection() as conn:
+        yield conn