launchpad-dev team mailing list archive

[Michael Hudson <michael.hudson@xxxxxxxxxxxxx>]

Jonathan Lange wrote:
> On Thu, Sep 24, 2009 at 10:02 AM, Martin Pool <mbp@xxxxxxxxxxxxx> wrote:
>> (Launchpad bounced my mail during the upgrade today)
>>
>>
>> ---------- Forwarded message ----------
>> From: Martin Pool <mbp@xxxxxxxxxxxxx>
>> Date: 2009/9/24
>> Subject: which version of bzr for launchpad?
>> To: Launchpad Community Development Team
>> <launchpad-dev@xxxxxxxxxxxxxxxxxxx>, Robert Collins
>> <robertc@xxxxxxxxxxxxxxxxx>, John Arbash Meinel
>> <john@xxxxxxxxxxxxxxxxx>, Ian Clatworthy
>> <ian.clatworthy@xxxxxxxxxxxxx>, Vincent Ladeuil
>> <v.ladeuil+lp@xxxxxxx>, Andrew Bennetts
>> <andrew.bennetts@xxxxxxxxxxxxx>
>>
>>
>> I had a talk to jml and thumper about this recently, and thought I
>> would send a note here for the larger audience.
>>
>> Bazaar now maintains two branches, a stable/bugfix-only 2.0 branch,
>> and an ongoing development branch 2.1dev.  (See
>> <http://doc.bazaar-vcs.org/developers/cycle.html>).  As much as we
>> can, we will make no changes to 2.0 that will break api compatibility,
>> or any other kind.  They will be able to interoperate on both the
>> network and formats.   The development branch may introduce new data
>> formats, though we don't immediately anticipate doing this.  It likely
>> will add new smartserver verbs, but it will have a fallback for older
>> servers.  2.1 will still be tested and get the same degree of care we
>> always have, but we'll be a bit more free to remove deprecated or
>> non-user-affecting compatibility code.  So the only difference is the
>> rate of change, not the degree of quality.
>>
>> The question then arises which version Launchpad should run for
>> codehosting, and the answer is that it will run the development
>> branch, 2.1b1 etc.  People using old clients should be fine, and
>> people using new features or formats introduced in the development
>> branch will be able to use them against Launchpad.  As we change APIs,
>> Launchpad may need to update their own code, but they do this anyhow
>> as part of their monthly integrations and it is not onerous.
>>
> 
> The subject of your email is phrased as a question, but the content is
> an answer, and I think it's a good one.
> 
>> Launchpad will at some point in the future add an edge codehost, which
>> will run Launchpad's own tip, then be merged to the lpnet (ie stable)
>> servers in monthly releases.  edge will run only slightly ahead with
>> the bzr version, for example being on 2.1b2 when lpnet is on 2.1b1.
>> This gives some opportunity for testing.
>>
> 
> FWIW, the edge codehosting service is waiting on our IS team to do
> some network configuration.
> 
>> The biggest risk seems to be that a change in 2.1.x may introduce
>> bugs, either to do with operation with old clients or otherwise.  The
>> best way to address this is (aside from general quality development)
>> to test each release as it's integrated on the staging and edge
>> codehost.  At least this way we will find any such issues earlier in
>> bzr's cycle rather than at the 2.1rc1 point.
>>
>> It may be interesting in the future to allow the client to specify the
>> remote bzr commandname as eg 'bzr-2.0' and then we could have several
>> available servers on the Launchpad side; this would require including
>> multiple bzr trees in the deployment.
>>
> 
> This would indeed be interesting. It would require a lot of work.

A wrinkle might come with plugin compatiblity.  We currently use bzr-git
and soon will use bzr-svn and hopefully bzr-hg.  /Perhaps/ we should
look at using the stable bzr for code imports -- I don't think this
would actually be particularly hard, technically speaking (you'd just
need to specify a different buildout.cfg for the launchpad trees on the
import slaves, and make sure that the rest of launchpad at least imports
with the stable branch of bzr).

Cheers,
mwh