Dataikuapi is not correctly honoring "DKU_NO_CHECK_CERTIFICATE" in requests

In theory, Dataiku supports using self-signed certificates by setting e.g. using an environmental variable DKU_NO_CHECK_CERTIFICATE or by setting no_check_certificate=True in the set_remote function call of the non-open source dataiku package.

However, this parameter is not passed to the api_client(), which causes requests to fail which are made to Dataiku instances using self-signed certificates. It is possible to mitigate this by setting the verify value of the internal Session object to false:

client = dataiku.api_client()
client._session.verify = False

Which is not obvious and requires looking through the internals of the package.

A fix at the central call site of the dataikuapi package, _perform_http:
https://github.com/dataiku/dataiku-api-client-python/blob/fc51e29a12a1f50717771522e1b450ae91ff4d87/dataikuapi/dssclient.py#L1228-L1233
would only be possible in parts by duplicating the logic to check the "DKU_NO_CHECK_CERTIFICATE" variable or config files, but would still fail for Dataiku session set up by using the set_remote_dss function call.

The best option would be to add a "no_check_certificate" parameter to the DSSClient class that can be set when creating an instance of the class. But as the DSSClient is also used by the closed-source dataiku package, it seems to me that this can't be solved by contributing to the open source dataikuapi package.

Start by reading DSSClient and _perform_http in dataikuapi/dssclient.py, then trace how sessions are created through api_client() and set_remote_dss(). Determine whether certificate verification settings can be propagated without relying on the closed-source dataiku package. Done means requests honor DKU_NO_CHECK_CERTIFICATE and the configured no_check_certificate value when using self-signed certificates.