[Pulp-dev] Consider moving distribution to top level resource.

Jeff Ortel jortel at redhat.com
Wed Nov 1 14:27:26 UTC 2017


On 10/31/2017 03:07 PM, Brian Bouterse wrote:
> What about a use case like this:   "As a user, I want a repo to auto-update two base paths to maintain an old
> base_path for backwards compatibility during a base_path restructuring transition."

Great use case, Brian.  Yes.  I agree this is compelling.

I have updated the issue to reflect that the Distribution.publisher_id will remain to support the one-to-many
relationship and indicate automatic distribution instead of ownership.

[0] https://pulp.plan.io/issues/3102

> 
> While ^ is not an MVP use case (I would argue), if we go forward with the feature to auto-update exactly 1
> Distribution as part of the MVP, we cannot modify it later to handle N Distributions later due to semver. If
> we can't modify it later to be more general, then we can never fulfill a use case like ^ with this same
> feature. So I'm +0 an MVP that can auto-update N Distributions after publish but -1 on having the MVP perform
> exactly 1 Distribution update for the semver concerns above ^.



> 
> What do others think about ^?
> 
> -Brian
> 
> 
> On Fri, Oct 27, 2017 at 10:53 AM, Jeff Ortel <jortel at redhat.com <mailto:jortel at redhat.com>> wrote:
> 
> 
> 
>     On 10/25/2017 12:00 PM, Brian Bouterse wrote:
>     > I'm +1 to this plan. There are several distinct points of value and I agree w/ all of them. I'm -0 to adding
>     > the Publisher.distribution_id field for auto publishing as an MVP feature. It's an important feature, but also
>                                                    ^^ did you mean auto distribution?
>     > if we had feedback from users later maybe we would position it differently. Maybe it should be a list of
>     > distributions 0,1,* instead of 0,1 perhaps? Semantic versioning would constrain our ability to change this
>     > after the 3.0 GA so we want to make sure what we do is right. This sounds right, but I'm not a user so I'm not
>     > totally sure.
>     The known use case for auto distribution comes from pulp2.  That is "As a user, I want my publication
>     automatically available through one distribution."  This is how pulp2 works today.  There may be a use case
>     for new publications to be automatically available through multiple distribution but I can't think of how that
>     would be useful.  Anyone else?  And, no user has yet asked for it.  Anyone asking for it?
> 
>     >
>     > I think this would be good to write up into Redmine and share a link to it.
> 
>     https://pulp.plan.io/issues/3102 <https://pulp.plan.io/issues/3102>
> 
>     >
>     > On Wed, Oct 25, 2017 at 9:15 AM, Jeff Ortel <jortel at redhat.com <mailto:jortel at redhat.com>
>     <mailto:jortel at redhat.com <mailto:jortel at redhat.com>>> wrote:
>     >
>     >
>     >
>     >     On 10/24/2017 09:29 PM, Michael Hrivnak wrote:
>     >     > There is a lot to like about this.
>     >     >
>     >     > Since the publisher is the one that would do the auto-updating of a distribution, it makes sense
>     for it to own
>     >     > a reference to the distribution it should be updating.
>     >     >
>     >     > One question: how might this impact authorization? I know that's not in the MVP, but we'll need to
>     tackle it
>     >     > eventually. It's convenient to say a specific user can do anything within the scope of a repo's
>     path. This may
>     >     > not be worth worrying too much about, but it is something to factor in.
>     >     >
>     >     > Beyond what you identified, the first thing I thought of is that it solves a hotfix use case for
>     which we've
>     >     > never offered a good solution. It goes like this:
>     >     >
>     >     > - user has a repo that changes over time
>     >     > - user makes a recent content set available to testing infrastructure, and eventually promotes that to
>     >     > production infrastructure. (in pulp 2 this was a copy between repos, and in pulp 3 of course it is
>     multiple
>     >     > distributions aiming at different publications)
>     >     > - user has a testing cycle of days, weeks or perhaps months (common in certain industries) before
>     a content
>     >     > set gets promoted
>     >     > - one day, the next heartbleed happens. User wants to forget all about the content set being
>     tested and needs
>     >     > to just deploy the heartbleed fix on top of the content set currently in production.
>     >
>     >     Exactly.  I was imagining the hotfix, Y stream, Z stream repositories/publications promoted through
>     the same
>     >     set of distributions.
>     >
>     >
>     >     >
>     >     > So how does the user bypass the normal flow and hotfix the production content set? If Distribution
>     was a
>     >     > top-level resource, it becomes simple. The user would create a new repo that is a clone of the
>     content set
>     >     > currently in production, then add just the heartbleed fix. They could update their testing
>     distribution to
>     >     > serve that publication for a brief period if they want, and then update the production
>     distribution to serve
>     >     > it. After the dust settles, they can go back to the normal repository and its flow of changing
>     content sets.
>     >     >
>     >     > What other factors can you folks think of?
>     >     >
>     >     >
>     >     > On Tue, Oct 24, 2017 at 4:24 PM, Jeff Ortel <jortel at redhat.com <mailto:jortel at redhat.com>
>     <mailto:jortel at redhat.com <mailto:jortel at redhat.com>>
>     >     <mailto:jortel at redhat.com <mailto:jortel at redhat.com> <mailto:jortel at redhat.com
>     <mailto:jortel at redhat.com>>>> wrote:
>     >     >
>     >     >     During a discussion with Austin to resolve a problem implementing #3033, an interested
>     question was
>     >     raised -
>     >     >     "Why do Distributions needs to be owned by Publishers?"  This question came up when considering a
>     >     solution to
>     >     >     a DRF difficulty related to both Publications and Distributions being nested under publisher/ AND
>     >     related to
>     >     >     each other.  The idea being considered was to move Distributions to a top level resource. 
>     Here are the
>     >     >     benefits:
>     >     >
>     >     >     1. Resolves current DRF nesting issue w/ #3033.  (This is minor).
>     >     >     2. A distribution could be updated to reference any publication.  This is more flexible.
>     >     >     3. Since Distribution.base_path is unique across all repositories/publishers, it might be more
>     >     intuitive to be
>     >     >     a top level resource?
>     >     >
>     >     >     Currently, the Distribution.publisher_id represents a parent-child relationship the mainly
>     exists to
>     >     support
>     >     >     automatic distribution.  When the publisher creates a new publication, it is automatically
>     >     associated to any
>     >     >     of the publisher's distributions marked as auto_updated=True.
>     >     >
>     >     >     There are two challenges to moving the Distribution to a top-level resources.
>     >     >
>     >     >     1. The distribution name is currently unique by (publisher_id, name).
>     >     >     2. This would break automatic distribution as currently implemented.
>     >     >
>     >     >     Here are a few options to resolving these challenges:
>     >     >
>     >     >     1. The name could be unique across all distributions.  This seems reasonable.
>     >     >     2. Redesign automatic distribution.  (see proposal below).
>     >     >     3. Reconsider automatic distribution.
>     >     >
>     >     >     ---
>     >     >
>     >     >     Proposal to redesign automatic distribution.
>     >     >
>     >     >     The use case for automatic distribution is similar to automatic publishing.  The user has
>     updated a
>     >     >     repository; has published it; and now wants to consume content.  This could be done by making
>     3 API
>     >     calls: 1
>     >     >     sync; 2 publish; 3 update-a-distribution.  But, based on pulp2, users want to do this with 1
>     API call.
>     >     >
>     >     >     So, here is the proposal.
>     >     >
>     >     >     1. Move distributions to the top level resource (no longer owned by a publisher).
>     >     >     2. Remove Distribution.publisher_id and Distribution.auto_updated.
>     >     >     3. Add (optional) Publisher.distribution_id.  When set, the referenced distribution will be
>     updated
>     >     with newly
>     >     >     created publications.
>     >     >
>     >     >
>     >     >     Publisher <---* Publication
>     >     >        |                ^ (0,1)
>     >     >        |                |
>     >     >        |                |
>     >     >        v (0,1)          |
>     >     >     Distribution --------
>     >     >
>     >     >     ---
>     >     >
>     >     >     I'm not convinced about all this but think we should consider.
>     >     >
>     >     >     Thoughts?
>     >     >
>     >     >
>     >     >     https://pulp.plan.io/issues/3033 <https://pulp.plan.io/issues/3033>
>     <https://pulp.plan.io/issues/3033 <https://pulp.plan.io/issues/3033>>
>     >     <https://pulp.plan.io/issues/3033 <https://pulp.plan.io/issues/3033>
>     <https://pulp.plan.io/issues/3033 <https://pulp.plan.io/issues/3033>>>
>     >     >
>     >     >
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>     >     >
>     >     >
>     >     >
>     >     >
>     >     > --
>     >     >
>     >     > Michael Hrivnak
>     >     >
>     >     > Principal Software Engineer, RHCE
>     >     >
>     >     > Red Hat
>     >     >
>     >
>     >
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