Re: [gentoo-alt] [prefix] Different install and build path

[Dirk Heinrichs]

Am Mittwoch, 7. November 2007 schrieb ext Fabian Groffen:
> On 07-11-2007 17:28:04 +0200, Dirk Heinrichs wrote:
> > Hi,
> >
> > I just found out about the prefixed portage project. Looks like it
> > finally implements functionality I requested already two years ago.
> > That's good news.
>
> My memory is bad, what in particular were/are you looking for?

See background below.

> > What I would like to know is the following: Would it be possible to
> > build for one prefix, but install into another?
>
> I'm not sure if I get what exactly it is that you want, and I'm not
> familiar with AFS (sorry Stefaan ;) ), but it looks a bit like
> automounted stuff, and in particular the BSD automounter's scheme.

No, it's far superior than that. It creates a global directory tree 
under /afs. The clients only mount /afs, the tree is assembled on the 
servers. Volumes are created on the servers and mounted into the tree 
somewhere, making them instantly visible on the clients. Volumes can be 
replicated (ro) for higher availability. However, if a ro replica of a 
volume exist, the client always prefers it over the rw replica, unless the 
path to the rw replica is used explicitely.

And that's the problem I want to solve. Install software into a different 
path than it was compiled for, automatically. Plus, after installation of 
each package, release the volume (replicate the changes to all ro 
replicas).

> Anyway.  What you can do these days is:
> a)
>   1. "emerge" a package with "buildpkg" in FEATURES (or use quickpg
>      afterwards)
>   2. make the binpkg (dir, or tbz alone) available through the
>      filesystem, or via PORTAGE_BINHOST (http and ftp I think)
>   3. "emerge" using -k or -K to use the binary and install it on the
>      other system with offset-prefix != build systems's prefix
>      (restriction here is that len(target-prefix) <= len(build-prefix))

There is no "other" system. All systems see the same directory tree 
below /afs. There is also now offset, or prefix. The installation path 
(rw-volume) simply differs from the runtime path (ro-replica).

> b)
>   1. set up portage for offset-prefix A
>   2. env EPREFIX=prefix-B emerge package
>      this would in theory allow to use a prefix installation to "clone"
>      itself, or for a build-host to maintain/compile for a target
>      prefix.
>      I must note that the latter only works on paper (need to iron some
>      issues out here) and the former I never tried.

Can try this.

> > Background: This would be an ideal thing for installing (and
> > distributing) software into the AFS filesystem tree. As you may know,
> > AFS supports read-only replication, were ro replicas of a volume (if
> > existing) are accessed with preference over rw replicas. However, the
> > rw replica can always be accessed through the so called rw path, like
> >
> > /afs/mydomain.com/myvolume  (ro)
> > /afs/.mydomain.com/myvolume (rw)
> >
> > The other thing that would be needed to support this is to be able to
> > run user defined actions at certain states, like in this case run "vos
> > release" after each successful install to synchronize the ro with the
> > rw replica.

Bye...

	Dirk
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