[Bf-committers] BF coordination meeting notes - 2019.08.12

[Dan McGrath]

Hi,

On Mon, Aug 12, 2019 at 8:00 AM Brecht Van Lommel <brechtvanlommel at gmail.com>
wrote:

> The idea would be to have a flow like this for example. I think it
> would help to get better quality reports, or to help users find
> solutions themselves in some cases.
>
> https://docs.google.com/document/d/1gxuBv6aeZjKgzMQmGYdaERKbd7VnllSa9s_ejl2hMGo/edit#bookmark=id.83ndneimph3m


Regarding the "Buildbot" section from the above Google doc:

> It would be good if a serious bug is introduced, we have an easy way to
> pin the buildbot download page to an earlier version without that bug until
> it is fixed.


Actually, this could potentially be possible using ZFS snapshots. The
directory is already available to the jail itself, so it would be a matter
of just rsync'ing back over the current contents of the download directory
-- which is what the PHP script enumerates, IIRC -- with the contents of
one of the snapshots. This could be done by had, or programatically, as
needed. Of course, the downside to merely rsync'ing back over top of the
current files, is that the next build bot run will replace the files again,
but this could possibly be the easiest to implement a "temp fix" by just
sym linking the broken file(s) to their /.zfs/snapshots/ alternative,
submitting the patch in advance, and then letting the next buildbot run
replace it. Not exactly the best solution, when you don't have strict
control to prevent builds from rolling out, mind you.

I would suggest at least creating a dataset in ZFS for just those files,
and modifying the current site to use symbolic links to point to an
alternate location, for as long as is needed. This might require some
tweaks to the PHP file that we use now (to ensure it follows the sym link),
but I don't see why this couldn't work. It also has the benefit of not
requiring extra permissions to the jail itself, just a one time creation of
a new dataset.

There is also the possibility of allowing for the ZFS dataset to be
manipulated from within the jail itself, thus allowing a script to say,
create or delete snapshots on the download directory, but I would generally
recommend against this, at least with the current design that we have for
jail configuration.


Cheers,

Dan