[Pulp-dev] Proposal: merge the content-app & streamer

[Dana Walker]

In light of the efficiency gains and lack of significant drawbacks, I'm +1
on this proposal.

--Dana


Dana Walker

Associate Software Engineer

Red Hat

<https://www.redhat.com>
<https://red.ht/sig>


On Mon, Dec 3, 2018 at 2:40 PM Dennis Kliban <dkliban at redhat.com> wrote:

> I like the idea of combining the two applications for all the reasons
> already outlined on this thread. The user experience is going to be
> simplified by this change. However, I want to point out that it will also
> alter the plugin writer experience. Plugin writers that want to have their
> own content app will now need to provide it as a plugin for the content app
> (which is not a Django project). We should be able to clearly document this
> for plugin writers. pulp_docker plugin will need to adopt this change. For
> that reason I'd like us to make a decision on this soon.
>
> On Fri, Nov 30, 2018 at 4:59 PM Jeff Ortel <jortel at redhat.com> wrote:
>
>> *BACKGROUND*
>>
>> The pulp3 content app and the streamer (in-progress) currently have a lot
>> of duplicate code and functionality.  At the very least, I think there is a
>> opportunity to refactor both and share code.  But, this would leave us with
>> two components with significant overlap in functionality.
>>
>> The functionality exclusive to the content-app:
>>   - Optionally delegate file serving to a web server. (Eg: mod_xsendfile).
>>   - Optional redirect to the streamer.
>>
>> The functionality exclusive to the streamer:
>>   - Using the Remote & RemoteArtifact to download the file and stream on
>> demand.
>>
>> Not much difference which raises the question: "Why do we have both?"  I
>> think the answer may be that we don't.
>>
>> *PROPOSAL*
>>
>> Let's pull the content-app out and merge it with the streamer.  The new
>> content (app) would have *streamer* architecture & functionality.  When
>> a requested artifact has not been downloaded, it would download/streamed
>> instead of REDIRECT.  This does mean that deployments and development
>> environments would need to run an additional service to serve content.  The
>> /pulp/content endpoint would be on a different port than the API.  I see
>> this separation as a healthy thing.  There is significant efficiency to be
>> gained as well.  Let's start with eliminating the REDIRECTs.  Cutting the
>> GET requests in half is a win for both the client, the network and the Pulp
>> web stack.  Next is database queries.  Since both applications needed to
>> perform many of the same queries, combining the applications will roughly
>> cut them in half as well.  Since the streamer is based on asyncio and so
>> would the merged app.
>>
>> There are probably lots of other pros/cons I have not considered but it
>> seems relatively straight forward.
>>
>> I'm thinking the new content app/service would be named: *pulp-content*.
>>
>> Thoughts?
>>
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