below is the UI draft for the feature proposed in [0]:

We propose a new feature that would allow users to specify "package filter" for
indexes. That way one can narrow down the set of packages that should be
mirrored. See [0] for motivation and some more details.

Setting filter

> devpi index <index_name> filter=<package_filter>

The client parses the <package_filter> file to make sure it comforms with the
specification (See 'Package filter syntax' below). If the syntax is correct, it
pushes it to the devpi server, where it is saved as property of the given index
and, if necessary, packages that are already mirrored but shouldn't be are

The filter keyword option can be used either during creation of an index, or by
itself, to modify an existing index, e.g.

> devpi index -c <index_name> filter=<package_filter>


> devpi index <index_name> filter=<package_filter>

The filtering can be turned off by giving no value to the filter keyword [1], e.g.

> devpi index <index_name> filter=

Viewing filter [2]

> devpi index <user>/<index_name>

Also lists an URL of the package filter file as pushed to the server [3]

Package filter syntax

A file containing on each line a package name (and optionally version
specification compatible with PEP 440) that ARE allowed to be mirrored. If the
version specification part is ommited, all versions of given package are
allowed. Lines begining with Lines begining with # are considered comments and
are not processed. Example package filter file:

# django <1.6 isn't mirrored because foo

[0] https://bitbucket.org/hpk42/devpi/issue/198/whitelisting-packages-that-can-be-mirrored
[1] Alternatively perhpaps by pointing it to an empty file?
[2] I'm quite unsure with this section, would appreciate a comment.
[3] I figured it would be better to give the URL instead of straigth up listing
     the packages, since:
        a) The filter could contain several hundered packages
        b) This way it seems simpler to modify the filter (wget > vim > push)

Let me know if I've missed something. :)