Re: [Q] `git fetch tag NAME' into mirror repo does not update HEAD, what to do?

[Brian Foster <brian.foster@innova-card.com>]

On Thursday 12 August 2010 19:02:49 Brandon Casey wrote:
> Brian Foster wrote:
> >  Bare repository ORIG's master looks like this [ I've updated
> >  all of the diagrams slightly to remove some confusion  -blf]:
> > 
> >    o--o--o--o--v1--o--v2--o--o--o [master &] HEAD
> > 
> >  where v1 and v2 are (annotated) tagged commits.
> > 
> >  Repository SLAVE is a mirror clone of ORIG which
> >  (very deliberately!) lags behind (i.e., [SLAVE's master's head]
> >  is one of the earlier (and usually tagged) commits
> >  on ORIG).  SLAVE's master was like this:
> > 
> >    o--o--o--o--v1 [master &] HEAD
> > 
> >  We wanted to update [SLAVE's master's head] to v2, so did:
> > 
> >    git fetch ORIG tag v2
> > 
> >  This gave us:
> > 
> >    o--o--o--o--v1 [master &] HEAD
> >                  \ 
> >                   o--v2
> > 
> >  It did not update SLAVE's [master's head] to v2, which we wanted[:]

       o--o--o--o--v1--o--v2 [master &] HEAD

> Are you using --mirror only so that the branch pointer in
> the mirror repository will be updated when you fetch?

 Correct.

> If you are not really interested in having a "real" mirror,
> then maybe you should set your mirror up to track a
> specific branch (or branches) in the mirrored repository.

 Now that seems like an excellent idea!

 The embarrassing thing is, we actually do _do_ something
 similar elsewhere in the process.  So we haven't got any
 great excuse for not thinking of it ....  ;-\ 

> You could have a branch named for example "for_mirror/master",
> in the mirrored repository (ORIG) that you would prepare.
> You could update the for_mirror/master branch when you were
> ready using 'git branch' like this:
> 
>    git branch -f for_mirror/master v2
> 
> In the mirror repository (SLAVE), you would update the
> fetchspec so that the mirror mirrored the branches below
> the "for_mirror" namespace in the remote repository
> like this:
> 
>    fetch = +refs/heads/for_mirror/*:refs/heads/*
> 
> Then, a simple 'git fetch' would fetch the updates (including
> tags) and update the branch pointer in the mirror like you want
> it to do.  Tracking multiple branches this way is possible just
> by creating another branch in the ORIG repository with the proper
> name.

 Another nice point about the above is it could deal
 with another procedural issue we have, which is the
 lack of a “staging area” for final test (a “pre-SLAVE”).
 Whilst we haven't (yet) had any (known) screw-ups in
 the final released system (what “mirror” SLAVE contains),
 it can happen.  The known screw-ups were all detected
 before it went to SLAVE, but by accident (IM(H?)O).

 Thanks for the idea/observation.

cheers!
	-blf-