[Pulp-dev] uniqueness constraints within a repository version

Tatiana Tereshchenko ttereshc at redhat.com
Sun Jul 21 10:22:43 UTC 2019 

+1 to the idea of a repo_key.

Should we also add the ability to apply custom validation of the content
being added?
Similar to a repo_key, Content model can optionally provide an additional
validator.
Use cases:
 - for pulp_file to avoid relative path overlap - e.g. 'a/b' and 'a'
 - for pulp_rpm to filter by signature/signing key

Plugins can solve it by defining their own stage but it seems like almost
any plugin needs to ensure absence of collisions specific to it, even the
simple pulp_file.
It means that our default pipeline becomes less useful and will be hardly
ever used by any [currently known] plugins.

Any thoughts?

Tanya


On Mon, Jul 8, 2019 at 9:09 PM Brian Bouterse <bbouters at redhat.com> wrote:

> I want to retell Simon's proposal to have "Content defines a 'repo_key'
> similar to a unit_key. This key must be unique within a repo version (and
> not globally like the unit_key."
>
> We could adopt his proposal to have the repo_key tuple defined on Content
> in pulpcore. If we left the add/remove APIs in core and adopt for both sync
> and add/remove a "keep newest to associate" functionality described earlier
> in the thread. This "keep newest to associate" code would be used by sync
> in the form of a core stage that is a generalized version of the
> RemoveDuplicates stage. This would become part of the default pipeline for
> all users of Stages API. I think this would be better than plugin writers
> implementing it over and over and also less effort for plugin wrtiers. This
> design would meet the current needs of pulp_cookbook, pulp_file, and
> pulp_rpm which are the only 3 places I know we have this problem so far,
> but I believe more content types are susceptible to this.
>
> What do you think we should do?
>
> Thanks!
> Brian
>
>
>
>
>
> On Thu, Jun 27, 2019 at 4:03 AM Tatiana Tereshchenko <ttereshc at redhat.com>
> wrote:
>
>> Sure, the code can be de-duplicated.
>> My main worry is that it's a responsibility of a plugin writer not to
>> forget to ensure uniqueness constraints within a repo version for every
>> workflow (sync, copy, anything else) where a repo version is created.
>> Every time before RepositoryVersion.create() is called, there should be a
>> check that there is no colliding content in a repo version.
>> It would be much more reliable and friendly, in my opinion, if plugin
>> writer could define rules/callbacks/whatever for each content and it would
>> be applied to any repository creation.
>> At the same time this eliminates the flexibility to define different
>> logic for content collision for different workflows, however I'm not sure
>> if such a use case exists or is desired.
>>
>> Tanya
>>
>>
>> On Wed, Jun 26, 2019 at 6:49 PM Austin Macdonald <amacdona at redhat.com>
>> wrote:
>>
>>> @Tanya Tereshchenko <ttereshc at redhat.com>
>>>
>>>> Do I understand correctly that it doesn't cover the sync case and it's
>>>> only about explicit repo version creation?
>>>>
>>>
>>> I don't mean that add/remove could not share code with remove duplicate
>>> stage. I wanted to point out that we have a problem here (how to remove
>>> duplicates) that has similar patterns to other problems with add remove
>>> (recursive, copy, deciding which content to keep with a collision, etc.) I
>>> don't doubt that pulpcore could help solve these problems, but I think that
>>> as we approach our GA, we should consider solving this problem (for now) by
>>> getting out of the way of plugin writers rather than by implementing code
>>> that is supposed to work for all plugins. I suspect that plenty of the
>>> plugins will be implementing their own add/remove anyway.
>>>
>>> On Tue, Jun 25, 2019 at 12:56 PM David Davis <daviddavis at redhat.com>
>>> wrote:
>>>
>>>> I don't think this solution would work in the case of creating a new
>>>> repository version. Suppose for example you had two content units that
>>>> collide, one in a repo version and one older unit that a user explicitly
>>>> wants to add to the repo version. If the latter one is older, then what
>>>> would happen?
>>>>
>>>> David
>>>>
>>>>
>>>> On Tue, Jun 25, 2019 at 12:48 PM Brian Bouterse <bbouters at redhat.com>
>>>> wrote:
>>>>
>>>>> Having a way for units to express their uniqueness per repo sounds
>>>>> good because then more areas of Pulp's code could answer the question:
>>>>> "will I have a duplicate if I add content X to repo_version Y".
>>>>>
>>>>> Let's assume we know that situation is about to occur during sync for
>>>>> example, what do we do about it? In the errata case we know the "new" one
>>>>> should replace the existing one. Maybe we start to 'order' the units with
>>>>> colliding repo keys and keep the newest one always? Would this work for
>>>>> pulp_cookbook and pulp_rpm? Would it generalize? Is this what you imagined?
>>>>>
>>>>> On Tue, Jun 25, 2019 at 5:30 AM Tatiana Tereshchenko <
>>>>> ttereshc at redhat.com> wrote:
>>>>>
>>>>>> Do I understand correctly that it doesn't cover the sync case and
>>>>>> it's only about explicit repo version creation?
>>>>>> So the suggestion is to implement the same logic twice: for sync case
>>>>>> - RemoveDuplicates stage and/or maybe some custom stage (e.g. to disallow
>>>>>> overlapping paths), and for direct repo version creation - your proposal.
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Mon, Jun 24, 2019 at 3:13 PM Austin Macdonald <amacdona at redhat.com>
>>>>>> wrote:
>>>>>>
>>>>>>> I have a design in mind for solving this problem:
>>>>>>>
>>>>>>> 1. Remove POST to RepositoryVersion (no general add/remove endpoint).
>>>>>>> 2. Add an endpoint to kick off an add/remove task, namespaced by
>>>>>>> plugin. ie `POST pulp/api/v3/docker/add-remove/`
>>>>>>>    This view can be provided to all plugins by the plugin template,
>>>>>>> and will be based on the current RepositoryVersionCreate:
>>>>>>>
>>>>>>> https://github.com/pulp/pulpcore/blob/master/pulpcore/app/viewsets/repository.py#L221-L258
>>>>>>>    Note: the main purpose of this view is to kick off the general
>>>>>>> add/remove task, which will be unchanged:
>>>>>>>
>>>>>>> https://github.com/pulp/pulpcore/blob/master/pulpcore/app/tasks/repository.py#L70
>>>>>>> 3. Add an add/remove serializer to the plugin API.
>>>>>>> 3. Plugins needing further customization can provide their own task
>>>>>>> and subclassed serializer.
>>>>>>>
>>>>>>> This gives the plugin writer full control over the endpoint
>>>>>>> (customizable arguments and validation), and full control over the flow
>>>>>>> (extra logic, depsolving, enforced uniqueness). It only uses the existing
>>>>>>> patterns (and existing required knowledge), but requires no work (other
>>>>>>> than using the template) for the simple case.
>>>>>>>
>>>>>>> On Mon, Jun 3, 2019 at 2:56 PM Simon Baatz <gmbnomis at gmail.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> On Mon, Jun 03, 2019 at 09:11:07AM -0400, David Davis wrote:
>>>>>>>> >    @Simon I like the idea behind the repo_key solution you came
>>>>>>>> up with.
>>>>>>>> >    Can you be more specific around cases you think that it
>>>>>>>> couldn't
>>>>>>>> >    handle? I imagine that plugin writers could use properties or
>>>>>>>> >    denormailzation (ie additional database columns) to solve
>>>>>>>> cases where
>>>>>>>> >    they need uniqueness across data that isn't in the database.
>>>>>>>> In a worst
>>>>>>>> >    case scenario, they can't use the pulpcore solution and just
>>>>>>>> have to
>>>>>>>> >    roll their own.
>>>>>>>>
>>>>>>>>
>>>>>>>> What I wrote probably sounded too pessimistic. You are right, in
>>>>>>>> most cases that should be doable.
>>>>>>>>
>>>>>>>> I agree that we could have a simple default solution that just
>>>>>>>> requires to specify a couple of field names in the easiest case.
>>>>>>>> As you
>>>>>>>> say, it should be possible use custom logic in a plugin if required.
>>>>>>>>
>>>>>>>> Here is the case I was thinking of that it can't handle:
>>>>>>>>
>>>>>>>> In pulp_file, a uniqueness constraint on "relative_path" would allow
>>>>>>>> content units "a" and "a/b" to be in a repo version.
>>>>>>>>
>>>>>>>> However, we may want file repos to be representable on an actual
>>>>>>>> file
>>>>>>>> system (e.g. when exporting them as tar files).  For the repo above,
>>>>>>>> this does not work, as "a" can't be a file and a directory at the
>>>>>>>> same time on a standard Unix file system.
>>>>>>>>
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> Pulp-dev mailing list
>>>>>>>> Pulp-dev at redhat.com
>>>>>>>> https://www.redhat.com/mailman/listinfo/pulp-dev
>>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Pulp-dev mailing list
>>>>>>> Pulp-dev at redhat.com
>>>>>>> https://www.redhat.com/mailman/listinfo/pulp-dev
>>>>>>>
>>>>>> _______________________________________________
>>>>>> Pulp-dev mailing list
>>>>>> Pulp-dev at redhat.com
>>>>>> https://www.redhat.com/mailman/listinfo/pulp-dev
>>>>>>
>>>>> _______________________________________________
>>>>> Pulp-dev mailing list
>>>>> Pulp-dev at redhat.com
>>>>> https://www.redhat.com/mailman/listinfo/pulp-dev
>>>>>
>>>> _______________________________________________
>>>> Pulp-dev mailing list
>>>> Pulp-dev at redhat.com
>>>> https://www.redhat.com/mailman/listinfo/pulp-dev
>>>>
>>> _______________________________________________
>> Pulp-dev mailing list
>> Pulp-dev at redhat.com
>> https://www.redhat.com/mailman/listinfo/pulp-dev
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listman.redhat.com/archives/pulp-dev/attachments/20190721/e86bb5b7/attachment.htm>

More information about the Pulp-dev mailing list