Create a socket connection when using SQLAlchemy

Create a Unix socket connection to Cloud SQL for PostgreSQL by using SQLAlchemy.

Documentation pages that include this code sample

To view the code sample used in context, see the following documentation:

• Connect using the Cloud SQL Auth proxy
• Connecting from App Engine flexible environment to Cloud SQL
• Connecting from App Engine standard environment to Cloud SQL
• Connecting from Cloud Functions to Cloud SQL
• Connecting from Cloud Run to Cloud SQL
• Managing database connections
• Overview to connecting

Code sample

Python

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# Remember - storing secrets in plaintext is potentially unsafe. Consider using
# something like https://cloud.google.com/secret-manager/docs/overview to help keep
# secrets secret.
db_user = os.environ["DB_USER"]
db_pass = os.environ["DB_PASS"]
db_name = os.environ["DB_NAME"]
db_socket_dir = os.environ.get("DB_SOCKET_DIR", "/cloudsql")
instance_connection_name = os.environ["INSTANCE_CONNECTION_NAME"]

pool = sqlalchemy.create_engine(

    # Equivalent URL:
    # postgresql+pg8000://<db_user>:<db_pass>@/<db_name>
    #                         ?unix_sock=<socket_path>/<cloud_sql_instance_name>/.s.PGSQL.5432
    # Note: Some drivers require the `unix_sock` query parameter to use a different key.
    # For example, 'psycopg2' uses the path set to `host` in order to connect successfully.
    sqlalchemy.engine.url.URL.create(
        drivername="postgresql+pg8000",
        username=db_user,  # e.g. "my-database-user"
        password=db_pass,  # e.g. "my-database-password"
        database=db_name,  # e.g. "my-database-name"
        query={
            "unix_sock": "{}/{}/.s.PGSQL.5432".format(
                db_socket_dir,  # e.g. "/cloudsql"
                instance_connection_name)  # i.e "<PROJECT-NAME>:<INSTANCE-REGION>:<INSTANCE-NAME>"
        }
    ),
    **db_config
)

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