draft advisory about network issues

[Robert Collins]

On Thu, 2009-05-07 at 15:16 +1000, Martin Pool wrote:
> 2009/5/7 Robert Collins <robert.collins at canonical.com>:
> > This is a draft of advise we should send our users about the 1.13/1.14
> > network headaches. We should send this to bazaar-announce, and forward
> > copies to known large users of bzr (including hosting sites such as
> > alioth, sourceforge, launchpad, and so on).
> 
> The noun is spelled 'advice' fwiw.

Indeed; oversight.

> > -----
> >
> > Networking bugs in bzr 1.13/1.14
> > ================================
> >
> > Bzr 1.13 introduced streaming fetch over the bzr:// protocol.
> > Unfortunately due to design oversight dating back to bzr 1.6 this was
> > not able to operate on many stacked branches due to the data in the
> > stacking branch being overly minimal. The server is unable to correctly
> > determine the deltas to send.
> 
> I think here I'd add a bit more about what the impact is and who it affects:
> 
>   If you're not using stacked branches this does not affect you.  [ok
> this should be obvious but in this kind of thing let's overcommunicate
> slighly.]  Bazaar will not create them by default unless you specify
> the --stacked option or set a server-side policy for them.  This
> policy is set on the Launchpad code host.  You can tell if there are
> any stacked branches by the presence of a .bzr/branch/stacked-on file.
> [Correct name?]
> 
>  If you are using stacked branches, then using either bzr 1.13 or 1.14
> to push data into them may create repositories that cannot be read.
> 
>   [What should people do with existing affected branches.]
> 
> Add the bug URLs here too and say updates will be posted there.

I think I've captured your intent; I've modified the prose to be less
colloquial and more specific.

> > There are bug fixes that all users of stacked branches should apply:
> 
> So ahead of this I think we need to say basically what the options
> are; to me they seem to be:

You're right that there are more options. Thats different to whether we
want to advertise them! After all 'stop using bzr' is also a valid
option to avoid the bug, but we don't want to recommend that.

>  * Go back to bzr 1.12 on the server

This would only defer it for people; as we have fixes created I'm not
really happy suggesting this to people.

>  * Don't push new stacked branches.

Also not really a good answer. 'Don't push new stacked branches with
older bzr clients' is perhaps ok.

>  * Run bzr.dev (and point to the nightly PPA)
> 
>  * Manually apply the fixes below.

I think I'll say 'If you are running Ubuntu you can obtain deb packages
of bzr.dev which includes these fixes'.


-----

Networking bugs in bzr 1.13/1.14
================================

Bzr 1.13 introduced streaming fetch over the bzr:// protocol.
Unfortunately due to design oversight dating back to bzr 1.6 this was
not able to operate on many stacked branches due to the data in the
stacking branch being overly minimal. The server is unable to correctly
determine the deltas to send.

If you are not using stacked branches this does not affect you.
Bazaar will not create stacked branches by default unless you specify
the --stacked option to push/branch, or set a server-side policy for
them. Launchpad sets a server-side policy for stacking - users of
launchpad will be using stacked branches. You can tell if a branch is
stacked by running 'bzr info BRANCHURL' and looking for 
     stacked on: URL
in the output.

If you are using stacked branches, then using bzr versions before
1.13.2, 1.14.2 or 1.14 and above may create repositories that cannot be
streamed from.

Resolving this issue
--------------------

Existing branches which are affected require a script run on them to fix
them. The script and instructions are in
https://bugs.launchpad.net/launchpad-code/+bug/354036.

bzr needs to be updated or patched:

On the bzr server:
Apply http://bazaar.launchpad.net/~bzr/bzr/trunk/revision/4307, as per
https://bugs.launchpad.net/launchpad-code/+bug/354036. This will be
included in the upcoming bzr 1.15.
Apply http://bazaar.launchpad.net/~bzr/bzr/trunk/revision/4342, as per
https://bugs.launchpad.net/ubuntu/+source/bzr/+bug/360791. This will
also be included in the upcoming bzr 1.15.

On client machines:
Run bzr 1.13.2 or bzr 1.14.2. Older versions of bzr will continue to
create problematic branches that will require the fixer script in
https://bugs.launchpad.net/launchpad-code/+bug/354036 to be run against
them.

If you are using Ubuntu, packages of bzr.dev are available via the
nightly Personal Package Archive
https://launchpad.net/~bzr-nightly-ppa/+archive/ppa.

There is another potential failure mode that may affect projects using
bzr-svn, or migrating from GNU Arch. If you encounter a 'Revision
REVISIONID not present' error when branching, you may be suffering
https://bugs.launchpad.net/bzr/+bug/368418. A fix for this is currently
in progress and will be included in 1.15.

For further information and support please contact the Bazaar community
via https://answers.launchpad.net/bzr, #bzr on irc.freenode.net, or
bazaar at lists.canonical.com.

-The Bazaar developers.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 197 bytes
Desc: This is a digitally signed message part
Url : https://lists.ubuntu.com/archives/bazaar/attachments/20090507/42816316/attachment.pgp