On Wed, Oct 25, 2017 at 11:24 AM, David Davis <[email protected]> wrote:
> I don’t know that the ambiguity around whether a task has a publication or > not is a big deal. If I call the publication endpoint, I’d expect a > publication task which either has 1 publication or 0 (if the publication > failed) attached to it. > > In terms of ambiguity, I see a worse problem around adding a task_id field > to publications. As a user, I don’t know if a publication failed or not > when I get back a publication object. Instead, I have to look up the task > to see if it is a real (or successful) publication. Moreover, since we > allow users to remove/clean up tasks, that task may not even exist anymore. > > I agree that the ephemeral nature of tasks makes the originally proposed solution non-deterministic. I am open to associating 'resources created' with a task instead. However, I still think there is value in changing the rest API endpoint for starting a publish task to POST /api/v3/repositories/<repo-id>/publishers/<type>/<name>/publications/. However, I will start a separate thread for that discussion. - Dennis > > David > > On Wed, Oct 25, 2017 at 11:03 AM, Brian Bouterse <[email protected]> > wrote: > >> >> >> On Tue, Oct 24, 2017 at 10:00 PM, Michael Hrivnak <[email protected]> >> wrote: >> >>> >>> >>> On Tue, Oct 24, 2017 at 2:11 PM, Brian Bouterse <[email protected]> >>> wrote: >>> >>>> Thanks everyone for all the discussion! I'll try to recap the problem >>>> and some of the solutions I've heard. I'll also share some of my >>>> perspective on them too. >>>> >>>> What problem are we solving? >>>> When a user calls "publish" (the action API endpoint) they get a 202 w/ >>>> a link to the task. That task will produce a publication. How can the user >>>> find the publication that was produced by the task? How can the user be >>>> sure the publication is fully complete? >>>> >>>> >>>> What are our options? >>>> 1) Start linking to created objects from task status. I believe its >>>> been clearly stated about why we can't do this. If it's not clear, or if >>>> there are other things we should consider, let's talk about it. >>>> Acknowledging or establishing agreement on this is crucial because a change >>>> like this would bring back a lot of the user pain from pulp2. I believe the >>>> HAL suggestion falls into this area. >>>> >>> >>> I may have missed something, but I do not think this is clear. I know >>> that Pulp 2's API included a lot of unstructured data, but that is not at >>> all what I'm suggesting here. >>> >>> It is standard and recommended practice for REST API responses to >>> include links to resources along with information about what type of >>> resource each link references. We could include a reference to the created >>> resource and an identifier for what type of resource it is, and that would >>> be well within the bounds of good REST API design. HAL is just one of >>> several ways to accomplish that, and I'm not pitching any particular >>> solution there. In any case, I'm not sure what the problem would be with >>> this approach. >>> >> >> I agree it is a standard practice for a resource to include links to >> other resources, but the proposal is to include "generic" links is >> different and creates a different user experience. I believe referencing >> the task from the publication will be easier for users and clients. When a >> user looks up a publication, they will always know they'll get between 0 >> and 1 links to a task. You can use that to check the state of the >> publication. If we link to "generic" resources (like a publication) from a >> task, then if I ask a user "do you expect task >> ede3af3e-d5cf-4e18-8c57-69ac4d4e4de6 to contain a link to a publication >> or not?" you can't know until you query it. I think that ambiguity was a >> pain point in Pulp2. I don't totally reject this solution, but this is an >> undesirable property (I think). >> >> >>> >>>> >>>> 2) Have the user find the publication via query that sorts on time and >>>> filters only for a specific publisher. This could be fragile because with a >>>> multi-user system and no hard references between publications and tasks, >>>> answering the question "which is the publication for me" is hard because >>>> another user could have submitted a publish too. While not totally perfect, >>>> this could work. >>>> >>> >>> In theory if a user queried for a publication from a specific publisher >>> that was created between the start and end times of the task, that should >>> unambiguously identify the correct publication. But depending on timestamps >>> is not a particularly robust nor confidence-inspiring way to reference a >>> resource. >>> >> Agreed and Agreed >> >> >>> >>>> >>>> 3) Have the user create a publication directly like any other REST >>>> resource, and help the user understand the state of that resource over >>>> time. I believe the proposal at the start of this thread is recommending >>>> this solution. I'm also +1 on this solution. >>>> >>> >>> I think the problem with this is that a user cannot create a >>> publication. A user can only ask a plugin to create a publication. Until >>> the plugin creates the publication, there is no publication. >>> >> >> Note a publication is an object, but really we mean a publication and >> it's related PublishedArtifact, PublishedMetadat, etc objects. It would be >> straightforward for a user to create a publication using the viewset and >> have the task associated with it call the publisher to build out the >> associated PublishedArtifact, PublishedContent, PublishedMetadata, etc. We >> should explore if this is good or not, but it is possible. >> >> As an aside, this is related to a problem everyone should be aware of: >> the existence of a publication does not guarantee that publication is >> finished publishing. Even with option 1, where the task creates the >> publisher and links to it in the task status, while the publisher is >> running it must save the Publication so that the PublishedArtifact, etc can >> link to it. So for any given publication, in order to know if it's "fully >> finished and consistent" you must be able to check the status of the >> associated task that produced it. >> >> >>> >>>> As an aside, I don't think considering versioned repos as a possible >>>> solution is helping us with this problem. The scope of the current problem >>>> is relatively small and the scope of planning for versioned repos is large. >>>> >>>> >>> Versioned repos is a potential solution. In that scenario, a user would >>> request publication of a specific repo version (perhaps defaulting to the >>> latest), the publication would be linked to that version, and that is an >>> easy mechanism for the user to find the publication they want. Ultimately >>> the user is interested in working with a specific content set anyway. They >>> get a repo to a state where it has the content they want, and then they >>> publish that content set. No matter what we do with publications, users >>> will think of them in terms of related content sets. A repo version is that >>> immutable content set they can work with confidently. >>> >> >> It's neat to me that that versions are snapshots of content and >> publications are snapshots of content. Publications already create much of >> the value propostion of versioned repos with publications. They allow you >> to work with specific content sets like you describe. Also they allow for >> rollback. So that is all great for our users. For this thread, I want to >> bring the conversation back to where it started, solving a small problem >> about linking two resources that already exist. >> >> >>> It helps the rollback scenario a lot as well. Versioning repos allows a >>> user to see what the differences are between two content sets, and thus two >>> different publications, which informs them about when and how far back they >>> should roll back a distribution. >>> >> >>> - user discovers a horrible flaw in a piece of content >>> - user queries for which version of the repo introduced that piece of >>> content >>> - user updates the distribution to serve the publication that came >>> before the one which introduced the piece of content, optionally >>> re-publishing that version in case its publication was deleted or had never >>> been made in the first place. >>> >>> -- >>> >>> Michael Hrivnak >>> >>> Principal Software Engineer, RHCE >>> >>> Red Hat >>> >> >> >> _______________________________________________ >> Pulp-dev mailing list >> [email protected] >> https://www.redhat.com/mailman/listinfo/pulp-dev >> >> > > _______________________________________________ > Pulp-dev mailing list > [email protected] > https://www.redhat.com/mailman/listinfo/pulp-dev > >
_______________________________________________ Pulp-dev mailing list [email protected] https://www.redhat.com/mailman/listinfo/pulp-dev
