On 18-03-15 07:03:11, Doug Hellmann wrote: > What I Want to Do > ----------------- > > 1. Update the requirements-check test job to change the check for > an exact match to be a check for compatibility with the > upper-constraints.txt value. > > We would check the value for the dependency from upper-constraints.txt > against the range of allowed values in the project. If the > constraint version is compatible, the dependency range is OK. > > This rule means that in order to change the dependency settings > for a project in a way that are incompatible with the constraint, > the constraint (and probably the global requirements list) would > have to be changed first in openstack/requirements. However, if > the change to the dependency is still compatible with the > constraint, no change would be needed in openstack/requirements. > For example, if the global list constraints a library to X.Y.Z > and a project lists X.Y.Z-2 as the minimum version but then needs > to raise that because it needs a feature in X.Y.Z-1, it can do > that with a single patch in-tree. >
I think what may be better is for global-requirements to become a gathering place for projects that requirements watches to have their smallest constrainted installable set defined in. Upper-constraints has a req of foo===2.0.3 Project A has a req of foo>=1.0.0,!=1.6.0 Project B has a req of foo>=1.4.0 Global reqs would be updated with foo>=1.4.0,!=1.6.0 Project C comes along and sets foo>=2.0.0 Global reqs would be updated with foo>=2.0.0 This would make global-reqs descriptive rather than prescriptive for versioning and would represent the 'true' version constraints of openstack. > We also need to change requirements-check to look at the exclusions > to ensure they all appear in the global-requirements.txt list > (the local list needs to be a subset of the global list, but > does not have to match it exactly). We can't have one project > excluding a version that others do not, because we could then > end up with a conflict with the upper constraints list that could > wedge the gate as we had happen in the past. > How would this happen when using constraints? A project is not allowed to have a requirement that masks a constriant (and would be verified via the requirements-check job). There's a failure mode not covered, a project could add a mask (!=) to their requirements before we update constraints. The project that was passing the requirements-check job would then become incompatable. This means that the requirements-check would need to be run for each changeset to catch this as soon as it happens, instead of running only on requirements changes. > We also need to verify that projects do not cap dependencies for > the same reason. Caps prevent us from advancing to versions of > dependencies that are "too new" and possibly incompatible. We > can manage caps in the global requirements list, which would > cause that list to calculate the constraints correctly. > > This change would immediately allow all projects currently > following the global requirements lists to specify different > lower bounds from that global list, as long as those lower bounds > still allow the dependencies to be co-installable. (The upper > bounds, managed through the upper-constraints.txt list, would > still be built by selecting the newest compatible version because > that is how pip's dependency resolver works.) > > 2. We should stop syncing dependencies by turning off the > propose-update-requirements job entirely. > > Turning off the job will stop the bot from proposing more > dependency updates to projects. > > As part of deleting the job we can also remove the "requirements" > case from playbooks/proposal/propose_update.sh, since it won't > need that logic any more. We can also remove the update-requirements > command from the openstack/requirements repository, since that > is the tool that generates the updated list and it won't be > needed if we aren't proposing updates any more. > > 3. Remove the minimum specifications from the global requirements > list to make clear that the global list is no longer expressing > minimums. > > This clean-up step has been a bit more controversial among the > requirements team, but I think it is a key piece. As the minimum > versions of dependencies diverge within projects, there will no > longer *be* a real global set of minimum values. Tracking a list of > "highest minimums", would either require rebuilding the list from the > settings in all projects, or requiring two patches to change the > minimum version of a dependency within a project. > > Maintaining a global list of minimums also implies that we > consider it OK to run OpenStack as a whole with that list. This > message conflicts with the message we've been sending about the > upper constraints list since that was established, which is that > we have a known good list of versions and deploying all of > OpenStack with different versions of those dependencies is > untested. > As noted above I think that gathering the min versions/maskings from openstack projects to be valuable (especially to packagers who already use our likely invalid values already). > After these 3 steps are done, the requirements team will continue > to maintain the global-requirements.txt and upper-constraints.txt > files, as before. Adding a new dependency to a project will still > involve a review step to add it to the global list so we can monitor > licensing, duplication, python 3 support, etc. But adjusting the > version numbers once that dependency is in the global list will be > easier. > Thanks for writing this up, I think it looks good in general, but like you mentioned before, there is some discussion to be had about gathering and creating a versionspec from all of openstack for requirements. -- Matthew Thode (prometheanfire)
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