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From "Mutton, James" <>
Subject Re: [DISCUSS] Multiple Repositories for Erlang Apps and Dependencies
Date Fri, 17 Jan 2014 19:01:32 GMT
Might I suggest that this sounds like good info to document on the wiki
for committers getting started.  I'd add it but I'm not in the allow-list.


On 1/17/14 4:00 AM, "Garren Smith" <> wrote:

>I'm claiming 2nd person added!
>On 17 Jan 2014, at 1:28 PM, Noah Slater <> wrote:
>> Psst. A little birdy tells me that if you ask nicely, the infra folks
>> will add you to the Apache GitHub org too, so you can show off your
>> Apache affiliation. I was the first person added. Because I may have
>> been the first to ask. ;)
>> On 17 January 2014 11:56, Noah Slater <> wrote:
>>> Awesome, thanks Paul.
>>> Note to all devs: if you want your contributions to CouchDB to show up
>>> on your GitHub profile, you have to star each of the repositories.
>>> (That's just how GitHub mechanics work for repo mirrors.)
>>> You can find them all here:
>>> On 17 January 2014 00:00, Paul Davis <>
>>>> New repos are up:
>>>> I'm gonna go through and initialize them with history from master or
>>>> one of the bigcouch and rcouch branches as appropriate.
>>>> On Thu, Jan 16, 2014 at 2:12 PM, Paul Davis
>>>><> wrote:
>>>>> Infrastructure ticket opened:
>>>>> On Thu, Jan 16, 2014 at 1:42 PM, Jan Lehnardt <>
>>>>>> On 16 Jan 2014, at 20:42 , Paul Davis <>
>>>>>>> It doesn't appear that this is objectionable to anyone. Does
>>>>>>> have an objection to us having infra/me create these repos to
>>>>>>> the bigcouch/rcouch merge work? This won't affect master or
>>>>>>> until those merges finish.
>>>>>> no objections.
>>>>>> Jan
>>>>>> --
>>>>>>> On Tue, Jan 14, 2014 at 11:02 PM, Paul J Davis
>>>>>>> <> wrote:
>>>>>>>>> On Jan 14, 2014, at 8:37 PM, Benoit Chesneau
>>>>>>>>><> wrote:
>>>>>>>>> On Wed, Jan 15, 2014 at 12:22 AM, Paul Davis
>>>>>>>>>> I've recently been having discussions about how to
handle the
>>>>>>>>>> repository configuration for various bits of CouchDB
>>>>>>>>>>post-merge. The
>>>>>>>>>> work that Benoit has been doing on the rcouch merge
branch have
>>>>>>>>>> touched on this topic as well.
>>>>>>>>>> The background for those unfamiliar is that the standard
>>>>>>>>>> procedure for Erlang is to have a single Erlang application
>>>>>>>>>> repository and then rely on rebar to fetch each dependency.
>>>>>>>>>> Traditionally in CouchDB land we've always just included
>>>>>>>>>>source to
>>>>>>>>>> all applications in a single monolithic repository
>>>>>>>>>> reimport changes from upstream dependencies.
>>>>>>>>>> Recently rcouch changed from the monolithic repository
to use
>>>>>>>>>> repositories for some dependencies. Originally the
>>>>>>>>>>used an
>>>>>>>>>> even more federated scheme that had each Erlang application
>>>>>>>>>> external repository (and the core couch Erlang application
>>>>>>>>>>in the
>>>>>>>>>> root repository). When Bob Newson and I did the initial
>>>>>>>>>>on the
>>>>>>>>>> BigCouch merge we pulled those external dependencies
into the
>>>>>>>>>> repository reverting back to the large monolithic
>>>>>>>>>> After trying to deal with the merge and contemplating
>>>>>>>>>> Erlang release things might work it's become fairly
>>>>>>>>>>that the
>>>>>>>>>> monolithic approach is a bit constrictive. For instance,
part of
>>>>>>>>>> rebar's versioning abilities lets you tag repositories
>>>>>>>>>> versions rather than manually updating versions in
source files.
>>>>>>>>>> Another thing I've found on other projects is that
having each
>>>>>>>>>> application in a separate repository requires developers
>>>>>>>>>>think a
>>>>>>>>>> bit more detailed about the public internal interfaces
>>>>>>>>>> out the system. We've done some work to this extent
already with
>>>>>>>>>> separating source directories but forcing commits
to multiple
>>>>>>>>>> repositories shoots up a big red flag that maybe
there's a high
>>>>>>>>>> of coupling between two bits of code.
>>>>>>>>>> Other benefits of having the multiple repository
setup is that
>>>>>>>>>> possible that this lends itself to being integrated
with the
>>>>>>>>>> plugin system. It'd be fairly trivial to have a script
>>>>>>>>>>went and
>>>>>>>>>> fetched plugins that aren't developed at Apache (as
>>>>>>>>>>./configure time
>>>>>>>>>> switch type of thing). Having a system like this
would also
>>>>>>>>>>allow us
>>>>>>>>>> to have groups focused on particular bits of development
>>>>>>>>>>have to
>>>>>>>>>> concern themselves with the unrelated parts of the
>>>>>>>>>> Given all that, I'd like to propose that we move
to having a
>>>>>>>>>> repository for each application/dependency that we
use to build
>>>>>>>>>> CouchDB. Each repository would be hosted on ASF infra
>>>>>>>>>>mirrored to
>>>>>>>>>> GitHub as expected. This means that we could have
the root
>>>>>>>>>> be a simple repo that contains packaging/release/build
>>>>>>>>>> would enable lots of the ideas offered on configurable
types of
>>>>>>>>>> release generation. I've included an initial list
>>>>>>>>>>repositories at
>>>>>>>>>> the end of this email. Its basically just the apps
that have
>>>>>>>>>> split out in either rcouch or bigcouch plus a few
other bits
>>>>>>>>>> CouchDB master.
>>>>>>>>>> I would also point out that even though our main
repo would
>>>>>>>>>>need to
>>>>>>>>>> fetch other dependencies from the internet to build
the final
>>>>>>>>>> we fully intend that our release tarballs would *not*
have this
>>>>>>>>>> requirement. Ie, when we go to cut a release part
of the
>>>>>>>>>>process the
>>>>>>>>>> RM would run would be to pull all of those dependencies
>>>>>>>>>> creating a tarball that would be wholly self contained.
Given an
>>>>>>>>>> apache-couchdb-x.y.z.tar.gz release file, there won't
be a
>>>>>>>>>> to have access to the ASF git repos.
>>>>>>>>>> I'm not entirely sure how controversial this is for
anyone. For
>>>>>>>>>> most part the reactions I remember hearing were more
>>>>>>>>>> whether the infrastructure team would allow us to
use this sort
>>>>>>>>>> configuration. I looked yesterday and asked and apparently
>>>>>>>>>> something we can request but as always we'll want
to verify
>>>>>>>>>>again if
>>>>>>>>>> we have consensus to move in this direction.
>>>>>>>>>> Anyone have comments or flames? Right now I'm just
interested in
>>>>>>>>>> feeling out what sort of (lack of?) consensus there
is on such a
>>>>>>>>>> change. If there's general consensus I'd think we'd
do a vote
>>>>>>>>>>in a
>>>>>>>>>> couple weeks and if that passes then start on down
this road
>>>>>>>>>>for the
>>>>>>>>>> two merge projects and then it would become part
of master once
>>>>>>>>>> land (as opposed to doing this to master and then
attempting to
>>>>>>>>>> rcouch/bigcouch onto that somehow).
>>>>>>>>>> This is a quick pass at listing what extra repositories
I'd have
>>>>>>>>>> created. Some of these applications only exist in
the bigcouch
>>>>>>>>>> rcouch branches so that's where the unfamiliar application
>>>>>>>>>>names are
>>>>>>>>>> from. I'd also point out that the documentation and
>>>>>>>>>>things are
>>>>>>>>>> just on a whim in that we could decouple that development
>>>>>>>>>> erlang development. I can see arguments for an against
>>>>>>>>>>I'm much
>>>>>>>>>> less concerned on that aspect than the Erlang parts
that are
>>>>>>>>>> affected by rebar/Erlang conventions.
>>>>>>>>>>  chttpd
>>>>>>>>>>  config
>>>>>>>>>>  couch
>>>>>>>>>>  couch_collate
>>>>>>>>>>  couch_dbupdates
>>>>>>>>>>  couch_httpd
>>>>>>>>>>  couch_index
>>>>>>>>>>  couch_mrview
>>>>>>>>>>  couch_plugins
>>>>>>>>>>  couch_replicator
>>>>>>>>>>  documentation
>>>>>>>>>>  ddoc_cache
>>>>>>>>>>  ets_lru
>>>>>>>>>>  fabric
>>>>>>>>>>  fauxton
>>>>>>>>>>  ibrowse
>>>>>>>>>>  jiffy
>>>>>>>>>>  mem3
>>>>>>>>>>  mochiweb
>>>>>>>>>>  oauth
>>>>>>>>>>  rebar
>>>>>>>>>>  rexi
>>>>>>>>>>  snappy
>>>>>>>>>>  twig
>>>>>>>>> I also contemplated this and and I am generally +1 on
this. And
>>>>>>>>> +1 to mirror them on the apache git if possible.  I have
>>>>>>>>>couple of
>>>>>>>>> comments though.
>>>>>>>>> Initially I also had everything separated in its own
>>>>>>>>>repository. 1
>>>>>>>>> year ago I merged back as one core repo the couchdb erlang
>>>>>>>>>applications and
>>>>>>>>> put all the dependencies in the refuge repository or
in the
>>>>>>>>>refuge CDN for
>>>>>>>>> the spidermonkey and ICU sources.
>>>>>>>>> I merged back as one core repo the couchdb erlang applications
>>>>>>>>>because they
>>>>>>>>> were a little too much dependant. Especially couch_httpd,
>>>>>>>>>couch_index and
>>>>>>>>> couch_mrview. These applications are not yet enough by
>>>>>>>>> Imo if we split everything in  their own apps, then we
>>>>>>>>>make sure
>>>>>>>>> that couch_httpd can be used without couch_index and
>>>>>>>>>couch_mrview (which
>>>>>>>>> means that "all_docs" is available in couch_httpd). Also
>>>>>>>>>should be able
>>>>>>>>> to just launch couch without any of the above. And probably
>>>>>>>>>without the
>>>>>>>>> need of an ini. The couch_query_server module thing is
>>>>>>>>>interesting case.
>>>>>>>>> bigcouch is also introducing `ddoc_cache` which I am
not sure
>>>>>>>>>why it is
>>>>>>>>> provided as a standalone app. Does it means it can be
>>>>>>>>>by another
>>>>>>>>> application eventually? Why not having it simply in the
>>>>>>>>> Does it needs to be updated separately?
>>>>>>>>> Also  all our base applications should also be named
>>>>>>>>>correctly so
>>>>>>>>> they will be strictly identified as erlang modules: 
"config" is
>>>>>>>>> generic, "ddoc_cache" too. Others are probably OK.
>>>>>>>>> There are probably other things that we could provide
as apps:
>>>>>>>>> - couch_daemon,
>>>>>>>>> - couch_js
>>>>>>>>> - couch_external
>>>>>>>>> - couch_stats
>>>>>>>>> - couch_compaction_daemon
>>>>>>>>> - couch_httpd_proxy
>>>>>>>>> Anyway again i'm +1 for this move, I really think it's
a good
>>>>>>>>> - benoit
>>>>>>>> I agree on most of this. Roughly I see three general points.
>>>>>>>> First, deciding on whether some things are external deps
>>>>>>>>definitely up for discussion. Whether couch_mrview is a different
>>>>>>>>app/repo is not necessarily clear cut. Personally I think
I over
>>>>>>>>engineered couch_index which blurs the lines a bit. If I could
>>>>>>>>wave a wand I'd have just couch_mrview and it'd be separate.
>>>>>>>>importantly I think the separate repos makes these things
>>>>>>>>apparent. The fact were discussing this sort of architecture
>>>>>>>>is suggestive that it's forcing us to think a bit harder.
>>>>>>>> Second is the aspect of composability. For instance the mrview
>>>>>>>>thing to me is obviously a different repo precisely so a user
>>>>>>>>could import couch (_core?) directly without requiring the
>>>>>>>>monkey dependency. The monolithic repo doesn't allow this
>>>>>>>>some very non-standard tooling.
>>>>>>>> Thirdly, app naming is always a contention. The config name
>>>>>>>>actually a hot code upgrade concern. We couldn't reuse
>>>>>>>>couch_config directly at the time. And Adam was also hopeful
>>>>>>>>could the it into a useful non-specific config app.
>>>>>>>> Fourthly, and related to secondly, we'll also want to look
>>>>>>>>splitting other apps out as necessary. The ones you listed
I think
>>>>>>>>aren't controversial it's just that no one has done it yet.
>>>>>>>>list was purely what existed so far without attempting to
>>>>>>>>things up more. I definitely agree we should carve more in
>>>>>>>>wanted to cover consensus that carving is the right direction.
>>>>>>>> Fifthly, I'm done typing on my phone. I'll fill in more thoughts
>>> --
>>> Noah Slater
>> --
>> Noah Slater

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