[Pulp-dev] creating repository version resources using a single REST endpoint

[Austin Macdonald]

>From a discussion with dkliban I see that this design could work. Plugin
tasks would be imported to pulpcore with a mechanism similar to the named
viewsets and serializers.

Pro: plugins would define tasks that follow a consistent interface (sync,
rich copy, etc)
Con: plugins would be restricted to tasks that are explicitly part of that
interface.

For the docs, I think this puts the endpoint in an awkward position. What
does each action do? Would the actions be generic enough that we could
correctly explain each of them as part of the core REST API docs?

We should also discuss synchronous validation. If a plugin's viewset
dispatches their own tasks, they can also define their own POST body
requirements aperform arbitrary synchronous validation. If the
RepositoryVersionViewset dispatches the task, synchronous validation could
still be done as part of the interface, with plugins also defining
something like "sync_validation" which would be run before the task is
dispatched.

Overall, I am convinced that this is a viable option, noting that this
design favors consistency between plugins over flexibility. If the plugin
viewsets are the ones to dispatch tasks instead, the plugins can do
whatever they need to, at the cost of consistency between plugins.

On Mon, Jan 8, 2018 at 3:15 PM, Dennis Kliban <dkliban at redhat.com> wrote:

> On Mon, Jan 8, 2018 at 2:39 PM, Austin Macdonald <amacdona at redhat.com>
> wrote:
>
>> I like the concept of single REST endpoint that is responsible for all
>> the ways to create a RepositoryVersion, but I don't quite understand how
>> this would work. Since the endpoint is purely pulpcore, how can the
>> RepositoryVersionViewSet import the plugin defined tasks that correspond to
>> the action specified by the user? The only way I see is to force plugin
>> writers to define all their tasks as methods on the Importer or Publisher,
>> which brings us back to the circular import problem.
>> https://pulp.plan.io/issues/3074
>>
>>
> Plugin writers would need to define the tasks inside the tasks module of
> their django app. pulpcore would then be able to discover the tasks defined
> by the plugin at startup. The 'operation' could be name spaced by the
> plugin name. Any tasks discovered in pulpcore would have pulpcore prepended
> to the operation name. e.g.: pulpcore.sync or pulp_rpm.deep_copy
>
> This would also address the circular import problem by moving the code
> that performs a sync outside the Importer. However, this would require the
> plugin writer to instantiate an Importer based on an 'href' passed in as an
> argument. And only then could the importer be used to drive the API.
>
>
>> Also, I think it would be a little unusual that the possible actions
>> specified in the POST body to a pulpcore endpoint would vary depending on
>> the plugin it is being used with. How would we document how to use this
>> endpoint?
>>
>>
> The endpoint would have a limited number of operations listed in our
> hosted docs. However, the rest API docs on each Pulp installation should be
> able to provide the user with a list of all available options.
>
>
>> On Mon, Jan 8, 2018 at 1:45 PM, Dennis Kliban <dkliban at redhat.com> wrote:
>>
>>> Enable users to POST to /api/v3/repositories/123abc456/versions/ with
>>> one required parameter 'operation'. This parameter would be an identifier
>>> for a task Pulp would run to create a new version. Any additional
>>> parameters passed in by the API user would be passed along to the task.
>>>
>>> pulpcore would provide the 'sync' task and the 'add_remove' task. 'sync'
>>> would accept an 'importer'. 'add_remove' would accept 'remove_content' and
>>> 'add_content'.
>>>
>>> Each plugin could provide any number of tasks for creating a repository
>>> version.
>>>
>>> pulpcore would always create the new repository version, hand it to the
>>> plugin code, and then mark it as complete after plugin code runs
>>> successfully. Alleviating the plugin writer of these concern.
>>>
>>> REST API users would always use the same end point to create a
>>> repository version. Plugin writers wouldn't have to worry about creating
>>> repository versions and managing the 'complete' state.
>>>
>>> What do you all think?
>>>
>>>
>>> _______________________________________________
>>> 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/20180108/d0834f11/attachment.htm>