requirements/README.rst
Doug Hellmann 3cdb85d35f remove readme content that moved to project-team-guide
This information is in the project-team-guide repository.

Change-Id: Ic72e0ca7bb07ada8698fd4919aa4e3906f4a96f0
Depends-On: https://review.openstack.org/561055
Signed-off-by: Doug Hellmann <doug@doughellmann.com>
2018-04-12 17:41:00 -04:00

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============================================
Global Requirements for OpenStack Projects
============================================
.. image:: https://governance.openstack.org/tc/badges/requirements.svg
:target: https://governance.openstack.org/tc/reference/tags/index.html
Why Global Requirements?
========================
Refer to the `Dependency Management`_ section of the *Project Team
Guide* for information about the history of the project and the files
involved.
.. _Dependency Management: https://docs.openstack.org/project-team-guide/dependency-management.html
Tools
=====
All the tools require openstack_requirements to be installed (e.g. in a Python
virtualenv). They all have help, which is the authoritative documentation.
update-requirements
-------------------
This will update the requirements in a project from the global requirements
file found in ``.``. Alternatively, pass ``--source`` to use a different
global requirements file::
update-requirements --source /opt/stack/requirements /opt/stack/nova
Entries in all requirements files will have their versions updated to match
the entries listed in the global requirements. Excess entries will cause
errors in hard mode (the default) or be ignored in soft mode.
generate-constraints
--------------------
Compile a constraints file showing the versions resulting from installing all
of ``global-requirements.txt``::
generate-constraints -p /usr/bin/python2.7 -p /usr/bin/python3 \
-b blacklist.txt -r global-requirements.txt > new-constraints.txt
edit-constraints
----------------
Replace all references to a package in a constraints file with a new
specification. Used by DevStack to enable git installations of libraries that
are normally constrained::
edit-constraints oslo.db "-e file://opt/stack/oslo.db#egg=oslo.db"
Proposing changes
=================
Look at the `Review Guidelines` and make sure your change meets them.
All changes to ``global-requirements.txt`` may dramatically alter the contents
of ``upper-constraints.txt`` due to adding or removing transitive
dependencies. As such you should always generate a diff against the current
merged constraints, otherwise your change may fail if it is incompatible with
the current tested constraints.
A change to the minimum specified vesion of a library in ``global-requirements.txt``
currenty requires adjusting the ``lower-constraints.txt`` file alongside with the
new constrainted coinstallable version of minimums.
Regenerating involves five steps.
1) Install the dependencies needed to compile various Python packages::
sudo apt-get install $(bindep -b)
2) Create a reference file (do this without your patch applied)::
generate-constraints -p /usr/bin/python2.7 -p /usr/bin/python3 \
-b blacklist.txt -r global-requirements.txt > baseline
3) Apply your patch and generate a new reference file::
generate-constraints -p /usr/bin/python2.7 -p /usr/bin/python3 \
-b blacklist.txt -r global-requirements.txt > updated
4) Diff them::
diff -p baseline updated
5) Apply the patch to ``upper-constraints.txt``. This may require some
fiddling. ``edit-constraint`` can do this for you **when the change
does not involve multiple lines for one package**.
Resources
=========
- Documentation: https://docs.openstack.org/requirements/latest/
- Wiki: https://wiki.openstack.org/wiki/Requirements
- Bugs: https://launchpad.net/openstack-requirements