SQLAlchemy custom keyword arguments failing with TypeError: 'argument' is is an invalid keyword argument for this function

Question

I need to pass in a custom argument to SQLAlchemy's create_engine function in order to SSL authorize my database connection with AWS RDS. here, here, and here it was recommended that I use SQLAlchemy's connect_args to pass in my custom keyword argument. I tried:

engine = create_engine(os.environ['DB_URI'], connect_args={'ssla':'amazon-rds-ca-cert.pem'})

However, I the following TypeError, which is the same error other posters said connect_args fixed for them:

TypeError: 'ssla' is an invalid keyword argument for this function

It seems like I'm doing this exactly right. I also tried passing the keyword arguments in the connection string:

mysql://name:password@localhost/test?sslca=amazon-rds-ca-cert.pem

And changing the names of the keyword arguments to exactly match the example in the sqlalchemy docs:

db = create_engine('mysql://name:password@localhost/test', connect_args = {'argument2':'bar'})

However, still no luck. It seems that the error is being thrown by MySQLdb in the error message, so perhaps it's an error there?

File "/Users/tobyweed/workspace/ftm/live-event-market/server/serverenv/lib/python2.7/site-packages/sqlalchemy/engine/default.py", line 411, in connect
    return self.dbapi.connect(*cargs, **cparams)
File "/Users/tobyweed/workspace/ftm/live-event-market/server/serverenv/lib/python2.7/site-packages/MySQLdb/__init__.py", line 86, in Connect
    return Connection(*args, **kwargs)
File "/Users/tobyweed/workspace/ftm/live-event-market/server/serverenv/lib/python2.7/site-packages/MySQLdb/connections.py", line 204, in __init__
    super(Connection, self).__init__(*args, **kwargs2)
TypeError: 'ssla' is an invalid keyword argument for this function

However, I don't have MySQLdb installed, so it must be SQLAlchemy which is using it. I have the latest version of SQLAlchemy (1.2.8), so that can't be it.

Please help!

nosklo · Accepted Answer · 2018-06-25 20:12:48Z

3

The argument is being passed upstream, that is, to your mysql dbapi module - All sqlalchemy does is call the connect function from the chosen module.

As you can see here https://dev.mysql.com/doc/connector-python/en/connector-python-connectargs.html sslca is not a valid parameter to the connect function - the correct parameter name would be ssl_ca I think?

In other words, you have to find out how to do what you want with python-mysql directly, without using sqlalchemy at all - sqlalchemy is not the culprit here

Also you say

However, I don't have MySQLdb installed, so it must be SQLAlchemy which is using it.

SQLAlchemy is not a database, it doesn't connect to anything. It is only a layer, you have to provide a database module for it to use to connect to databases.

answered Jun 25, 2018 at 20:12

nosklo

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5 Comments

Toby Weed Over a year ago

Smart, you're right. However, I tried ssl_ca, (and ssl_cert), which are supposedly valid parameters--no change to the error message besides the updated name.

Toby Weed Over a year ago

Also I think SQLAlchemy must automatically handle the connection with MySQLdb (no providing by me necessary), because it all works swimmingly without any database module configuration by me (if I remove the ssl_ca param). Although I do have mysqlclient installed.

nosklo Over a year ago

I assure you that SQLAlchemy CAN'T connect to any database by itself - it will always use some other module.

nosklo Over a year ago

I suggest using the excellent oursql to connect to mysql databases - we use it in production here. The parameter there is named ssl and it works fine.

Toby Weed Over a year ago

SQLAlchemy automatically uses MySQLdb. But anyways, it turns out the documentation for MySQL's connect params is slightly misleading--MySQLdb's connect function actually requires the SSL params to be formatted like: {'ssl':{'ca':'value'}} instead of {'sslca':'value'}

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