.netrc behaviour is not documented

[tmewett]

The Source subclass DownloadableFileSource reads login credentials from ~/.netrc. This class is used by the included 'tar' source as well as third-party plugins, since it's part of the public API. However, this behaviour is not documented anywhere.

It would be great to have user-facing documentation for this, ideally in its own page such that supporting plugins can link to it.

[juergbi]

Yes, we should have documentation for that. When deciding on documentation structure, we should consider that other credential fetching mechanisms may be added in the future (such as credential helper support suggested in #2148 (comment) / discussed on the mailing list).

[AedanM]

I'll take a look to add this