Ah, and forgot - can you please also add a pytest?

Thanks for the PR! Probably during time of UV integration we missed testing with a external index... thanks for reporting and providing the patch!

I just have two requests - which unfortunately would add a bit of complexity but... (1) When we initially integrated the support for other index URLs we explicitly did not add the index/extra index URLs to the command line but decided to write the pip-conf to ensure that the command line will not spoil/expose secrets in a shared environment because credentials will be in command line. Even though secrets are usually masked in logs still there is a residual risk that other traces in logs would spoil credentials. As it is a bit sad that UV does not pick-up the pip.cinf, the other alternative described is using ENV variables to define indexes and credentials (above the linked chapter in https://docs.astral.sh/uv/concepts/indexes/#defining-an-index e.g. via UV_INDEX). Can you change the PR to use ENV's and prevent adding CLI parameters?

(2) I see with the change the passed index URLs are added as extra-index URLs - but for PIP we made it explicitly that they are not "just extra" but the first one listed is the primary and then further are going to be extra, otherwise maybe private package lookups would be exposed to pypi.org. So I would kindly request making this for UV in the same way, first index_url should be the primary site and the next ones are extra.

Ah and I assume the CI failure is un-related to this PR...

Thanks for the review! 😊
I implemented the following points:

• Passing the index URLs to uv using environment variables now instead of command line arguments
• Changed the implementation so that the first index URL is used as UV_DEFAULT_INDEX and additional index URLs are used as UV_INDEX (this is the same as UV_EXTRA_INDEX_URL, which is deprecated).
• Updated documentation to explain handling of multiple index URLs
• Adapted unit tests

Nice!