Create a connection using the Cloud SQL Python Connector

Open a connection to Cloud SQL for SQL Server by using the Cloud SQL Python Connector.

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For detailed documentation that includes this code sample, see the following:

Code sample


To authenticate to Cloud SQL for SQL Server, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

import os

from import Connector, IPTypes
import pytds

import sqlalchemy

def connect_with_connector() -> sqlalchemy.engine.base.Engine:
    Initializes a connection pool for a Cloud SQL instance of SQL Server.

    Uses the Cloud SQL Python Connector package.
    # Note: Saving credentials in environment variables is convenient, but not
    # secure - consider a more secure solution such as
    # Cloud Secret Manager ( to help
    # keep secrets safe.

    instance_connection_name = os.environ[
    ]  # e.g. 'project:region:instance'
    db_user = os.environ.get("DB_USER", "")  # e.g. 'my-db-user'
    db_pass = os.environ["DB_PASS"]  # e.g. 'my-db-password'
    db_name = os.environ["DB_NAME"]  # e.g. 'my-database'

    ip_type = IPTypes.PRIVATE if os.environ.get("PRIVATE_IP") else IPTypes.PUBLIC

    connector = Connector(ip_type)

    connect_args = {}
    # If your SQL Server instance requires SSL, you need to download the CA
    # certificate for your instance and include cafile={path to downloaded
    # certificate} and validate_host=False. This is a workaround for a known issue.
    if os.environ.get("DB_ROOT_CERT"):  # e.g. '/path/to/my/server-ca.pem'
        connect_args = {
            "cafile": os.environ["DB_ROOT_CERT"],
            "validate_host": False,

    def getconn() -> pytds.Connection:
        conn = connector.connect(
        return conn

    pool = sqlalchemy.create_engine(
        # ...
    return pool

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