first working version

utils/db/db.py

@@ -0,0 +1,59 @@
+
+import logging
+from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine, async_sessionmaker
+from sqlalchemy.pool import NullPool
+
+class DbConnector:
+    _instances = {}
+
+    def __new__(cls, db_id="default"):
+        # print("==================")
+        # [print(f"{i} -> {id(cls._instances[i])}") for i in cls._instances]
+        # print("==================")
+        if db_id not in cls._instances:
+            cls._instances[db_id] = super().__new__(cls)
+        return cls._instances[db_id]
+
+    def __init__(self, db_id:str="default"):
+        self.logger = logging.getLogger("spirent_service_db_connector")
+
+    def init(self, db_type:str, host:str, port:int, db_name:str, user:str, password:str):
+        """
+
+        :param db_type: Example: mysql, postgresql, ...
+        :param host:
+        :param port:
+        :param db_name:
+        :param user:
+        :param password:
+        """
+
+        self.db_type = db_type
+        self.host = host
+        self.port = port
+        self.name = db_name
+        self.user = user
+        self.password = password
+
+        protocol = {
+            'mysql': 'mysql+aiomysql',
+            'postgresql': 'postgresql+asyncpg',
+        }
+
+        sqlalchemy_database_url = f"{protocol[self.db_type]}://{user}:{password}@{host}:{port}/{db_name}"
+        # for security reason, password not print in logs.
+        sqlalchemy_database_url_log = f"mysql://{user}:******@{host}:{port}/{db_name}"
+        self.logger.debug(f"Connecting to db {sqlalchemy_database_url_log}")
+
+        self.engine = create_async_engine(sqlalchemy_database_url, poolclass=NullPool)
+        self.async_session_local = async_sessionmaker(bind=self.engine,
+                                                      expire_on_commit=False,
+                                                      class_=AsyncSession,
+                                                      autoflush=False,
+                                                    )
+
+    def get_db(self):
+        return self.async_session_local
+
+
+