Format¶

global-requirements.txt supports a subset of pip requirement file contents. Distributions may only be referenced by name, not URL. Options (such as -e or -f) may not be used. Version specifiers, environment markers and comments are all permitted. A single distribution may be listed more than once if different specifiers are required with different markers - for instance, if a dependency has dropped Python 2.7 support.

upper-constraints.txt is machine generated and nothing more or less than an exact list of versions.

Enforcement for Test Runs¶

Enforcement in Projects¶

All projects that have accepted the requirements contract (as listed in projects.txt) are expected to run a requirements compatibility job. This job ensures that a project can not change any dependencies to versions not compatible with global-requirements.txt. It also ensures that those projects can not add a requirement that is not already in global-requirements.txt. This check-requirements job should be merged in infra before proposing the change to projects.txt in openstack/requirements.

Automatic Sync of Accepted Requirements¶

If an updated requirement is proposed to OpenStack and accepted to global-requirements.txt, the system then also automatically pushes a review request for the new requirements definition to the projects that include it.

For instance: if a review is accepted to global-requirements.txt that increases the minimum version of python-keystoneclient, the system will submit patches to all the OpenStack projects that list python-keystoneclient as a requirement or test requirement to match this new version definition.

This is intended as a time saving device for projects, as they can fast approve requirements syncs and not have to manually worry about whether or not they are up to date with the global definition.

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"

General Review Criteria¶

• No specifications for library versions should contain version caps

  As a community we value early feedback of broken upstream requirements, so version caps should be avoided except when dealing with exceptionally unstable libraries.

  If a library is exceptionally unstable, we should also be considering whether we want to replace it over time with one that is stable, or to contribute to the upstream community to help stabilize it.

• Libraries should contain a sensible known working minimum version

  Bare library names are bad. If it’s unknown what a working minimum is, look at the output of pip freeze at the end of a successful DevStack/tempest run and use that version. At least that’s known to be working now.

• Commit message should refer to consuming projects(s)

  Preferably, the comments should also identify which feature or blueprint requires the new specification. Ideally, changes should already be proposed, so that its use can be seen.

• The blacklist is for handling dependencies that cannot be constrained. For instance, linters which each project has at a different release level, and which make projects fail on every release (because they add rules) - those cannot be globally constrained unless we coordinate updating all of OpenStack to the new release at the same time - but given the volunteer and loosely coupled nature of the big tent that is infeasible. Dependencies that are only used in unconstrained places should not be blacklisted - they may be constrained in future, and there’s no harm caused by constraining them today. Entries in the blacklist should have a comment explaining the reason for blacklisting.

• Reviews that only update projects.txt should be workflow approved alongside or before other reviews in order to have the OpenStack Proposal Bot propagation be useful as soon as possible for the other projects. For project removal or addition, the +1 from the current PTL (or core if the PTL proposed the change) should be enough.

For new Requirements¶

• Is the library actively maintained?

  We really want some indication that the library is something we can get support on if we or our users find a bug, and that we don’t have to take over and fork the library.

  Pointers to recent activity upstream and a consistent release model are appreciated.

• Is the library good code?

  It’s expected, before just telling everyone to download arbitrary 3rd party code from the internet, that the submitter has taken a deep dive into the code to get a feel on whether this code seems solid enough to depend on. That includes ensuring the upstream code has some reasonable testing baked in.

• Is the library python 3 compatible?

  OpenStack will eventually need to support python 3. At this point adding non python 3 compatible libraries should only be done under extreme need. It should be considered a very big exception.

• Is the library license compatible?

  The library should be licensed as described in Licensing requirements, and the license should be described in a comment on the same line as the added dependency. If you have doubts over licensing compatibility, like for example when adding a GPL test dependency, you can seek advice from Robert Collins (lifeless), Monty Taylor (mordred) or Jim Blair (jeblair).

• Is the library already packaged in the distros we target (Ubuntu latest / Fedora latest)?

  By adding something to OpenStack global-requirements.txt we are basically demanding that Linux Distros package this for the next release of OpenStack. If they already have, great. If not, we should be cautious of adding it. Finding Distro Status

• Is the function of this library already covered by other libraries in global-requirements.txt?

  Everyone has their own pet libraries that they like to use, but we do not need three different request mocking libraries in OpenStack.

  If this new requirement is about replacing an existing library with one that’s better suited for our needs, then we also need the transition plan to drop the old library in a reasonable amount of time.

• Is the library required for OpenStack project or related dev or infrastructure setup? (Answer to this should be Yes, of course) Which?

  Please provide details such as gerrit change request or launchpad bug/blueprint specifying the need for adding this library.

• If the library release is managed by the Openstack release process does it use the cycle-with-intermediary release type?

  This is needed to ensure that updated releases that consume requirements updates are available for integration/coninstallability tests with other projects.

• Do I need to update anything else?

  When new library is added, initial version of release needs to be added to upper-constraints.txt. After that, OpenStack Proposal Bot will propose updates.

For Upgrading Requirements Versions¶

• Why is it impossible to use the current version definition?

  Everyone likes everyone else to use the latest version of their code. However, deployers really don’t like to be constantly updating things. Unless it’s actually impossible to use the minimum version specified in global-requirements.txt, it should not be changed.

  Leave that decision to deployers and distros.

• Changes to update the minimum version of a library developed by the OpenStack community can be approved by one reviewer, as long as the constraints are correct and the tests pass.

Finding Distro Status¶

From the OpenStack distro support policy:

OpenStack will target its development efforts to latest Ubuntu/Fedora, but will not introduce any changes that would make it impossible to run on the latest Ubuntu LTS or latest RHEL.

As such we really need to know what the current state of packaging is on these platforms (and ideally Debian, Gentoo, and SUSE as well).

For people unfamiliar with Linux Distro packaging you can use the following tools to search for packages:

• Ubuntu - http://packages.ubuntu.com/
• Fedora - https://apps.fedoraproject.org/packages/
• Gentoo - https://packages.gentoo.org/
• SUSE - https://build.opensuse.org/project/show/devel:languages:python

For upper-constraints.txt changes¶

If the change was proposed by the OpenStack CI bot, then if the change has passed CI, only one reviewer is needed and they should +2 +A without thinking about things.

If the change was not proposed by the OpenStack CI bot, and only changes the upper-constraints.txt entry for a new library release, then the change should be approved if it passes the tests. See the README.rst in openstack/releases for more details of the release process.

If the change was not proposed by the OpenStack CI bot, and is not related to releasing one of our libraries, and does not include a global-requirements.txt change, then it should be rejected: the CI bot will generate an appropriate change itself. Ask in #openstack-infra if the bot needs to be run more quickly.

Otherwise the change may be the result of recalculating the constraints which changed when a global-requirements.txt change is proposed. In this case, ignore the changes to upper-constraints.txt and review the global-requirements.txt component of the change.

stable-branch maintenance¶