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From Noah Slater <>
Subject Re: [DISCUSS] Multiple Repositories for Erlang Apps and Dependencies
Date Fri, 17 Jan 2014 19:09:57 GMT
Good plan. What's your wiki username? I'll add you.

On 17 January 2014 20:01, Mutton, James <> wrote:
> 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.
> :)
> </JamesM>
> 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 use
>>>>>>>> the bigcouch/rcouch merge work? This won't affect master
>>>>>>>> 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
>>>>>>>>>>>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
>>>>>>>>>>> procedure for Erlang is to have a single Erlang
application per
>>>>>>>>>>> repository and then rely on rebar to fetch each
>>>>>>>>>>> Traditionally in CouchDB land we've always just
included the
>>>>>>>>>>>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 BigCouch
>>>>>>>>>>>used an
>>>>>>>>>>> even more federated scheme that had each Erlang
application in
>>>>>>>>>>> external repository (and the core couch Erlang
application was
>>>>>>>>>>>in the
>>>>>>>>>>> root repository). When Bob Newson and I did the
initial hacking
>>>>>>>>>>>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 apparent
>>>>>>>>>>>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 to
>>>>>>>>>>>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 that
>>>>>>>>>>>went and
>>>>>>>>>>> fetched plugins that aren't developed at Apache
(as a
>>>>>>>>>>>./configure time
>>>>>>>>>>> switch type of thing). Having a system like this
would also
>>>>>>>>>>>allow us
>>>>>>>>>>> to have groups focused on particular bits of
development not
>>>>>>>>>>>have to
>>>>>>>>>>> concern themselves with the unrelated parts of
the system.
>>>>>>>>>>> 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 and
>>>>>>>>>>>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 of
>>>>>>>>>>>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 concerned
>>>>>>>>>>> whether the infrastructure team would allow us
to use this sort
>>>>>>>>>>> configuration. I looked yesterday and asked and
apparently its
>>>>>>>>>>> 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
>>>>>>>>>>>names are
>>>>>>>>>>> from. I'd also point out that the documentation
and fauxton
>>>>>>>>>>>things are
>>>>>>>>>>> just on a whim in that we could decouple that
development from
>>>>>>>>>>> erlang development. I can see arguments for an
against those.
>>>>>>>>>>>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 a
>>>>>>>>>>couple of
>>>>>>>>>> comments though.
>>>>>>>>>> Initially I also had everything separated in its
own source
>>>>>>>>>>repository. 1
>>>>>>>>>> year ago I merged back as one core repo the couchdb
>>>>>>>>>>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
>>>>>>>>>>because they
>>>>>>>>>> were a little too much dependant. Especially couch_httpd,
>>>>>>>>>>couch_index and
>>>>>>>>>> couch_mrview. These applications are not yet enough
>>>>>>>>>> Imo if we split everything in  their own apps, then
we should
>>>>>>>>>>make sure
>>>>>>>>>> that couch_httpd can be used without couch_index
>>>>>>>>>>couch_mrview (which
>>>>>>>>>> means that "all_docs" is available in couch_httpd).
Also we
>>>>>>>>>>should be able
>>>>>>>>>> to just launch couch without any of the above. And
>>>>>>>>>>without the
>>>>>>>>>> need of an ini. The couch_query_server module thing
is an
>>>>>>>>>>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 replaced
>>>>>>>>>>by another
>>>>>>>>>> application eventually? Why not having it simply
in the  couch
>>>>>>>>>> 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
>>>>>>>>> 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
>>>>>>>>>thing to me is obviously a different repo precisely so
a user
>>>>>>>>>could import couch (_core?) directly without requiring
the spider
>>>>>>>>>monkey dependency. The monolithic repo doesn't allow this
>>>>>>>>>some very non-standard tooling.
>>>>>>>>> Thirdly, app naming is always a contention. The config
name was
>>>>>>>>>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 at
>>>>>>>>>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. My
>>>>>>>>>list was purely what existed so far without attempting
to carve
>>>>>>>>>things up more. I definitely agree we should carve more
in just
>>>>>>>>>wanted to cover consensus that carving is the right direction.
>>>>>>>>> Fifthly, I'm done typing on my phone. I'll fill in more
>>>> --
>>>> Noah Slater
>>> --
>>> Noah Slater

Noah Slater

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