Hi! We want to support external mirrors other than PyPI. tl;dr The basics are mostly clear. Migration from a mirror could use input. Mirroring of devpi indexes needs more thought. I'd say we only support mirrors that provide a PyPI simple view where each project has one folder. For "findlinks" like private package storages which have all packages in one folder, I recommend to use CheesePrism and mirror that. I don't think we could support that lazily, as each file needs to be inspected for metadata, so we would have to download everything. When creating a mirror index, you provide the root url of the simple view (like https://pypi.python.org/simple/) and you can set the cache expiry time (defaults to 1800 seconds). The index settings are "mirror_url" and "mirror_cache_expiry". Mirrors are lazy, exactly like root/pypi is at the moment. To enable migration, we add support to "push" from a mirror into a regular index (also useful to selectively get pypi packages into an index) and look into "bulk pushing". Any thoughts on this? We should rename "pypi_whitelist" into "mirror_whitelist" or something like that. We will do a 3.0.0 anyway and can switch this during export/import. Should we add a setting that exempts a mirror from the whitelisting, or should we just get people to migrate to a regular index to avoid the need to whitelist packages? What about mirroring a devpi index? I see 3 scenarios: 1. Just mirror +simple of the index. + works now - problem is, that all inherited indexes and pypi would be mirrored as well. 2. Mirror a view which excludes mirrors. 3. Mirror a view that excludes any inherited indexes. I think both 2 and 3 have valid use cases. We need good names for the URL, I didn't come up with good ones yet (is there one word for "not inheriting"). We could later optimize devpi mirroring in various ways. For example with a serial header and with a notification protocol, though I'm not sure more than the serial is really necessary for most use cases. Regards, Florian Schulze