Open Stack

Two things I forgot to mention:

Currently there is another break point in the diagram of releases when X1
is released. Currently Horizon does not use upper-constraints and thus will
immediately pick up the new xstatic release file, potentially breaking
things. This is easy to fix - I will be proposing a patch soon.

SOLUTION 6 - make zuul capable of performing atomic cross-repository
commits.

    Richard

Sent from my portable device, please excuse the brevity.
On 8 Mar 2016 15:52, "Richard Jones" <r1chardj0n3s at gmail.com> wrote:

> We've solved *most* of the issues around releasing new xstatic packages,
> documented here[1] (and related documentation).
>
> We have one final issue that's blocking us, which is that during the
> xstatic release there will be a point at which Horizon may be broken from
> an integrated point of view - some of the interfaces may not work and fail
> tests. The process goes something like this:
>
> ​Note: this assumes that depends-on can reliably bring in patches from all
> over the place into a gate environment, which is technically possible, but
> not necessarily correct today.
>
> The problem is that because we can't atomically update both
> upper-constraints *and* Horizon at the same time (or upper-constraints
> *and* xstatic-angular, or Horizon *and* xstatic-angular) we run into a
> situation where Horizon will be running against the wrong version of
> xstatic-angular.
>
> So we break one of the basic assumptions of the OpenStack world: that
> every single commit in every repository for the integrated environment will
> pass tests.
>
> In the Python world, we code around this by making Horizon compatible with
> both the X and X1 versions of xstatic-angular (if it was a Python library).
> In Javascript land this is much more difficult - Javascript libraries tend
> to break compatibility in far more interesting ways. Maintaining
> compatibility across CSS and font releases is also a difficult problem,
> though changes here are unlikely to break Horizon enough that gate tests
> would fail. So, solution 1 to the problem is:
>
> SOLUTION 1: always maintain Horizon compatibility across xstatic library
> releases.
>
> This is potentially very difficult to guarantee. So, a second solution has
> been proposed:
>
> SOLUTION 2: move the upper-constraints information for *the xstatic
> libraries only* from the global upper-constraints file into Horizon's
> repository.
>
> This allows us to atomically update both Horizon and the xstatic library
> version, removing the potential to break because of the version mismatch.
> Unfortunately it means that we have version compatibility issues with
> anything else that wants to install alongside Horizon that also uses
> xstatic packages. For example, Horizon plugins. We could move Horizon
> plugins into the Horizon repository to solve this. /ducks
>
> A variation on this solution is:
>
> SOLUTION 3: allow Horizon to locally override upper-constraints for the
> time needed to merge a patch in devstack.
>
> This solution allows Horizon to atomically update itself and the xstatic
> library, but it also means installing Horizon in a CI/CD environment
> becomes more difficult due to the need to always pull down the
> upper-constraints file and edit it. We could code this in to tox, but that
> doesn't help eg. devstack which needs to also do this thing.
>
> SOLUTION 4: vendor the javascript
>
> Heh.
>
> SOLUTION 5: have dependencies on xstatic move from global requirements to
> Horizon
>
> This is similar to 2 & 3 with some of the same drawbacks (multiple users
> of xstatic) but also we'd need a change to global-requirements handling to
> ignore some entries in Horizon's requirements.
>
> Your thoughts on any and all of the above are requested.
>
>
>     Richard
>
> [1] https://review.openstack.org/#/c/289142/
>
>
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