How to set connection timeout in SQLAlchemy

The right way is this one (connect_timeout instead of connection_timeout):

create_engine(db_url, connect_args={'connect_timeout': 10})

...and it works with both Postgres and MySQL

docs sqlalchemy connect-args

ps: (the timeout is defined in seconds)

For whoever is using Flask-SQLAlchemy instead of plain SQLAlchemy, you can choose between two ways for passing values to SQLAlchemy's create_engine:

1. Use SQLALCHEMY_ENGINE_OPTIONS configuration key (Flask-SQLAlchemy>=2.4 required)

SQLALCHEMY_ENGINE_OPTIONS = {
    'connect_args': {
        'connect_timeout': 5
    }
}

2. Or, in alternative, use engine_option when instantiating flask_sqlalchemy.SQLAlchemy

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
db = SQLAlchemy(
    engine_options={ 'connect_args': { 'connect_timeout': 5 }}
)

db.init_app(app)

EDIT: The examples are using the connect_timeout argument that works (at least) for MySQL and PostgreSQL (value represent seconds), other DBMS may require different argument name to be passed to affect the connection timeout. I suggest to check your DBMS manual to check for such option.