[Pulp-dev] Namespacing plugins, looking for feedback

Tatiana Tereshchenko ttereshc at redhat.com
Wed Jan 2 17:57:42 UTC 2019 

Thank you all for the discussion so far.
The question - the type field and namespacing in content summary - is
solved with https://pulp.plan.io/issues/4185.

The last remaining question is whether we want to prepend endpoints for
master/detail models with plugin label. If yes, then everything or for
Content only.
See details on the issue https://pulp.plan.io/issues/4279.

Examples of the suggested change:

/api/v3/content/rpm/packages/ --> /api/v3/content/pulp_rpm/packages/
/api/v3/remotes/rpm/ --> /api/v3/content/remotes/pulp_rpm/rpm/
/api/v3/publishers/rpm/ --> /api/v3/content/publishers/pulp_rpm/rpm/

Changes which will be needed in plugins:
  - adjust the value of the `endpoint_name` attribute in the viewsets
we introduce changes to

Please provide feedback, here or on the issue
https://pulp.plan.io/issues/4279.
This is an RC blocker, so it would be great to groom it over the next
couple of days.

Thank you,
Tanya

On Thu, Dec 20, 2018 at 9:41 AM Tatiana Tereshchenko <ttereshc at redhat.com>
wrote:

> Since we are leaning towards prepending types for _all_ master/detail
> models and not only for the content model, that Django fix is no longer
> important for us.
>
> Tanya
>
> On Wed, Dec 19, 2018 at 6:18 PM Daniel Alley <dalley at redhat.com> wrote:
>
>> David, was that a vote to make it explicit?
>>
>> I would regard this as fairly intuitive as far as "magic-ness" goes,
>> acceptable from the user POV in my opinion.  And if Django is explicitly
>> trying to support this functionality and relies on it working properly, and
>> has a unittest for it going forwards, then I'm fairly confident it won't be
>> too fragile.  My vote is +1.
>>
>> My only concern (and it's not a major one) is that a plugin that needed
>> to be renamed might have problems with this.  But I think that would be
>> resolvable with a migration.
>>
>> Tanya, will we need to remove the workaround once Django 2.2 comes out?
>> If so, we should file a Refactor task for it.
>>
>> On Tue, Dec 18, 2018 at 9:39 AM David Davis <daviddavis at redhat.com>
>> wrote:
>>
>>> +1
>>>
>>> David
>>>
>>>
>>> On Tue, Dec 18, 2018 at 9:31 AM Brian Bouterse <bbouters at redhat.com>
>>> wrote:
>>>
>>>> There is also an issue w/ my suggestion in that it's highly magical.
>>>> The class name is likely going to go through a case mutation and if not
>>>> it's going to be finicky in terms of its case. So now I'm thinking the
>>>> plugin writer should have to define it to keep it simple and explicit (not
>>>> implicit and magical).
>>>>
>>>> On Tue, Dec 18, 2018 at 9:27 AM David Davis <daviddavis at redhat.com>
>>>> wrote:
>>>>
>>>>> Would it be possible to default to class name but let plugin writers
>>>>> override this? I would imagine in some cases plugin writers might want to
>>>>> change the name (eg cases where you can't use type as the class name like
>>>>> File).
>>>>>
>>>>> David
>>>>>
>>>>>
>>>>> On Tue, Dec 18, 2018 at 9:23 AM Brian Bouterse <bbouters at redhat.com>
>>>>> wrote:
>>>>>
>>>>>>
>>>>>>
>>>>>> On Tue, Dec 18, 2018 at 9:07 AM Tatiana Tereshchenko <
>>>>>> ttereshc at redhat.com> wrote:
>>>>>>
>>>>>>> Brian,
>>>>>>> the current PR [0] does exactly what you describe, it uses label
>>>>>>> which is taken from the plugin subclass of PulpPluginAppconfig + TYPE
>>>>>>> defined on the detail model.
>>>>>>> FWIW, there is an option to use plugin class name and not a plugin
>>>>>>> writer defined TYPE, e.g. pulp_file.filecontent, pulp_rpm.package,
>>>>>>> pulp_rpm.updaterecord, etc.
>>>>>>>
>>>>>> +1 to using the classname. Having the plugin class name used would
>>>>>> allow the user to not repeat themselves as much. I think it's likely the
>>>>>> class name == TYPE in almost all cases. The plugin writer would have 1 less
>>>>>> requirement on them at Content model definition time and that helps achieve
>>>>>> the "less burden on plugin writers" goal for pulp.
>>>>>>
>>>>>>>
>>>>>>> Jeff, to answer your questions:
>>>>>>>
>>>>>>>> 1. why do all the plugins begin with "pulp_"?
>>>>>>>>
>>>>>>> This is how django app label is defined in every plugin so far, see
>>>>>>> pulp_file case [1].
>>>>>>> Whatever is defined there is used as a plugin name.
>>>>>>>
>>>>>>> 2. can the plugin name get pre-pended when it's loaded by core?
>>>>>>>>
>>>>>>>> I lean toward TYPE=<plugin>.<type>
>>>>>>>
>>>>>>> Just to clarify, there is a class arttriburte `TYPE` and there is a
>>>>>>> `type` field on a model. I guess you suggest type = <plugin>.<TYPE>.
>>>>>>>
>>>>>>> We can probably do it on a master model in the save method [2], just
>>>>>>> initially the change was proposed for Content models only.
>>>>>>> If we decide to namespace all master/detail objects, I agree we can
>>>>>>> do it n a more generic way, than just redefine __init__ on a specific
>>>>>>> class.
>>>>>>>
>>>>>>
>>>>>>> Tanya
>>>>>>>
>>>>>>> [0]  https://github.com/pulp/pulp/pull/3801
>>>>>>> [1]
>>>>>>> https://github.com/pulp/pulp_file/blob/24881314372b9c1c505ff687c15238126b261afa/pulp_file/app/__init__.py#L10
>>>>>>> [2]
>>>>>>> https://github.com/pulp/pulp/blob/master/pulpcore/app/models/base.py#L76-L83
>>>>>>>
>>>>>>> On Tue, Dec 18, 2018 at 12:58 PM Ina Panova <ipanova at redhat.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> +1 to namespace master/detail as well.
>>>>>>>> +1 to Brian's suggestion to try.
>>>>>>>>
>>>>>>>> --------
>>>>>>>> Regards,
>>>>>>>>
>>>>>>>> Ina Panova
>>>>>>>> Software Engineer| Pulp| Red Hat Inc.
>>>>>>>>
>>>>>>>> "Do not go where the path may lead,
>>>>>>>>  go instead where there is no path and leave a trail."
>>>>>>>>
>>>>>>>>
>>>>>>>> On Tue, Dec 18, 2018 at 12:15 AM Brian Bouterse <
>>>>>>>> bbouters at redhat.com> wrote:
>>>>>>>>
>>>>>>>>> +1 to namespacing all Master/Detail objects (Remotes, Publishers,
>>>>>>>>> etc). Namespacing will increase consistency w/ the user experience and will
>>>>>>>>> avoid plugin-to-plugin naming collisions. @ttereshc +1 to the url changes
>>>>>>>>> and content summary changes you've described.
>>>>>>>>>
>>>>>>>>> I think it would be ideal if the app specified its 'label'
>>>>>>>>> attribute on the PulpPluginAppconfig subclass, e.g here in pulp_file
>>>>>>>>> https://github.com/pulp/pulp_file/blob/24881314372b9c1c505ff687c15238126b261afa/pulp_file/app/__init__.py#L10
>>>>>>>>> Then the Model for, e.g. the FileContent would have the second portion of
>>>>>>>>> the string 'file' as an example and Master/Detail would assemble them.
>>>>>>>>>
>>>>>>>>> Is this implementation how you imagined it?
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Mon, Dec 17, 2018 at 9:29 AM Tatiana Tereshchenko <
>>>>>>>>> ttereshc at redhat.com> wrote:
>>>>>>>>>
>>>>>>>>>> Just to clarify, the type field is not used in the endpoint
>>>>>>>>>> construction, so two changes described in the original e-mail are
>>>>>>>>>> independent.
>>>>>>>>>>
>>>>>>>>>> In my opinion:
>>>>>>>>>>  - it is possible to have type collisions.
>>>>>>>>>>  - it is possible to have the same endpoints (endpoint_name in a
>>>>>>>>>> viewset).
>>>>>>>>>>
>>>>>>>>>> FWIW, the endpoint collision is not unique to the master/detail
>>>>>>>>>> models' endpoints. A plugin, in theory, can define any endpoint they want.
>>>>>>>>>> Though not preventing collisions it for endpoints related to
>>>>>>>>>> master/detail models makes it easier to create such collision accidentally.
>>>>>>>>>>
>>>>>>>>>> Tanya
>>>>>>>>>>
>>>>>>>>>> On Mon, Dec 17, 2018 at 2:27 PM David Davis <
>>>>>>>>>> daviddavis at redhat.com> wrote:
>>>>>>>>>>
>>>>>>>>>>> Is it possible (under the current model, without namespacing) to
>>>>>>>>>>> have type collisions in the database for master/detail models? Like what if
>>>>>>>>>>> two plugins define two Contents with the same type or two Remotes with the
>>>>>>>>>>> same type? This kind of leads me to believe we should namespace everything.
>>>>>>>>>>> On the Ansible plugin for example, I started working on a git Remote[0].
>>>>>>>>>>> Luckily I chose "ansible_git" as the type but I could see plugin writers
>>>>>>>>>>> running into problems if they are not so careful.
>>>>>>>>>>>
>>>>>>>>>>> [0]
>>>>>>>>>>> https://github.com/pulp/pulp_ansible/pull/38/files#diff-debb42c875c19140793de39be3696ee3
>>>>>>>>>>>
>>>>>>>>>>> David
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On Sun, Dec 16, 2018 at 4:41 PM Tatiana Tereshchenko <
>>>>>>>>>>> ttereshc at redhat.com> wrote:
>>>>>>>>>>>
>>>>>>>>>>>> There is an issue [0] of colliding type names in the content
>>>>>>>>>>>> summary which evolved into more general namespacing problem for plugins.
>>>>>>>>>>>>
>>>>>>>>>>>> The suggested changes [1] are:
>>>>>>>>>>>>  1. include plugin name into the content summary
>>>>>>>>>>>>
>>>>>>>>>>>> "content_summary": {
>>>>>>>>>>>>     "pulp_rpm.package": 50,
>>>>>>>>>>>>     "pulp_rpm.errata": 2,
>>>>>>>>>>>>     "pulp_file.file": 5
>>>>>>>>>>>> }
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> 2. include plugin name into content endpoints
>>>>>>>>>>>> /api/v3/content/file/files/ --> /api/v3/content/pulp_file/files/
>>>>>>>>>>>> /api/v3/content/rpm/packages/ -->
>>>>>>>>>>>> /api/v3/content/pulp_rpm/packages/
>>>>>>>>>>>> /api/v3/content/rpm/errata/ --> /api/v3/content/pulp_rpm/errata/
>>>>>>>>>>>> ...
>>>>>>>>>>>>
>>>>>>>>>>>> For the change #1, not only content summary output is changed
>>>>>>>>>>>> but the type itself in the database. If the content type is used somewhere
>>>>>>>>>>>> in the filters, it should be specified in that format:
>>>>>>>>>>>> "plugin_name.plugin_type". Does it makes sense to extend the master model
>>>>>>>>>>>> and have a plugin name field and a type field, instead of putting
>>>>>>>>>>>> preformatted string into the type field?
>>>>>>>>>>>>
>>>>>>>>>>>> For the change #2, endpoints are namespaced only for the
>>>>>>>>>>>> content endpoint and not for other endpoints related to master/detail
>>>>>>>>>>>> models, like remotes, publishers, etc. It's inconsistent, however it makes
>>>>>>>>>>>> the most sense to have it for content endpoints.
>>>>>>>>>>>>
>>>>>>>>>>>> Any concerns or thoughts?
>>>>>>>>>>>>
>>>>>>>>>>>> Thank you,
>>>>>>>>>>>> Tanya
>>>>>>>>>>>>
>>>>>>>>>>>> [0] https://pulp.plan.io/issues/4185#note-8
>>>>>>>>>>>> [1] https://github.com/pulp/pulp/pull/3801
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