wishlist: parseable dependency list

Hi guys!

First of all, thanks so much for working on PBR, which is really a wonderful software for package maintainers. So far, I just love it.

Robert Collins told me that requirements.txt and test-requirements.txt are going away, being integrated in setup.cfg. I don't mind if it does, but what I would need then, would be an easy way to extract the dependencies from setup.cfg. Generating the egg-info is *not* what I want, as I don't want any file to be written when designing a Debian package.

For example, what would be great would be something like:

pbr extract-runtime-depends

and

pbr extract-test-depends

that would just output on stdout a list of package and their required version. Large amount of bonus points if it can only tell me about the lower bound of the dependencies (as this is practically the only information which should be wired in the debian/control file).

My end result would be something like this, which I currently already produce with "pkgos-parse-requirements" (included in the recent versions of openstack-pkg-tools package in both Debian and Ubuntu):

Build-Depends: debhelper (>= 9),
               dh-python,
               dh-systemd,
               openstack-pkg-tools (>= 23~),
               po-debconf,
               python-all,
               python-pbr,
               python-setuptools,
               python-sphinx,
Build-Depends-Indep: python-babel,
                     python-barbicanclient (>= 3.0.1),
                     python-boto,
                     python-cinderclient (>= 1:1.1.0),
                     python-coverage,
                     python-decorator,
                     python-eventlet (>= 0.16.1),
                     python-fixtures,
                     python-glanceclient (>= 1:0.15.0),
                     python-greenlet,
                     python-hacking,
                     python-ironicclient (>= 0.2.1),
                     python-iso8601,
                     python-jinja2,
                     python-jsonschema,
                     python-keystonemiddleware (>= 1.5.0),
                     python-lxml,
                     python-migrate (>= 0.9.5),
                     python-mock,
                     python-mox3,
                     python-mysqldb,
                     python-netaddr,
                     python-neutronclient (>= 2.3.11),
                     python-oslo.concurrency (>= 1.8.0),
                     python-oslo.config (>= 1:1.9.3),
                     python-oslo.context (>= 0.2.0),
                     python-oslo.db (>= 1.7.0),
                     python-oslo.i18n (>= 1.5.0),
                     python-oslo.log (>= 1.0.0),
                     python-oslo.messaging (>= 1.8.0),
                     python-oslo.middleware (>= 1.0.0),
                     python-oslo.rootwrap (>= 1.6.0),
                     python-oslo.serialization (>= 1.4.0),
                     python-oslo.utils (>= 1.4.0),
                     python-oslo.vmware (>= 0.11.1),
                     python-oslosphinx (>= 2.5.0),
                     python-oslotest (>= 1.5.1),
                     python-paramiko,
                     python-paste,
                     python-pastedeploy,
                     python-psutil,
                     python-psycopg2,
                     python-pyasn1,
                     python-requests-mock (>= 0.6.0),
                     python-rfc3986,
                     python-routes,
                     python-six (>= 1.9.0),
                     python-sqlalchemy,
                     python-stevedore (>= 1.3.0),
                     python-suds,
                     python-tempest-lib (>= 0.4.0),
                     python-testtools,
                     python-webob,
                     subunit,
                     testrepository,
                     websockify,
Depends: python-babel,
         python-boto,
         python-cinderclient (>= 1:1.1.0),
         python-decorator,
         python-eventlet (>= 0.16.1),
         python-glanceclient (>= 1:0.15.0),
         python-greenlet,
         python-iso8601,
         python-jinja2,
         python-jsonschema,
         python-keystonemiddleware (>= 1.5.0),
         python-lxml,
         python-migrate (>= 0.9.5),
         python-netaddr,
         python-neutronclient (>= 2.3.11),
         python-oslo.concurrency (>= 1.8.0),
         python-oslo.config (>= 1:1.9.3),
         python-oslo.context (>= 0.2.0),
         python-oslo.db (>= 1.7.0),
         python-oslo.i18n (>= 1.5.0),
         python-oslo.log (>= 1.0.0),
         python-oslo.messaging (>= 1.8.0),
         python-oslo.middleware (>= 1.0.0),
         python-oslo.rootwrap (>= 1.6.0),
         python-oslo.serialization (>= 1.4.0),
         python-oslo.utils (>= 1.4.0),
         python-paramiko,
         python-paste,
         python-pastedeploy,
         python-psutil,
         python-pyasn1,
         python-rfc3986,
         python-routes,
         python-six (>= 1.9.0),
         python-sqlalchemy,
         python-stevedore (>= 1.3.0),
         python-webob,
         websockify,
         ${misc:Depends},
         ${python:Depends},

I can of course parse and rework the output of pbr with such proposed new options instead of the currently existing requirements.txt. Though the thing which I don't want is too much hacking extracting the needed info from setup.cfg so that it produces what I have already right now through the requirements.txt.

Just to make it clear: this currently is only helpers for me, as a package maintainer, and this is not (yet) a fully automated tool. However, I may some day implement this as a lintian check (this is on my todo list), so probably it'd be a good idea to have it written in a not-so-dirty way.