tech-pkg: atomic pkgsrc

Subject: atomic pkgsrc
To: None <tech-pkg@netbsd.org>
From: James K. Lowden <jklowden@schemamania.org>
List: tech-pkg
Date: 05/12/2004 22:57:45

I spend quite a lot of time thinking about how to make pkgsrc easier to
administer. I've tried the sandbox, and I've read about pkgviews, but I
think I have a truly simple idea. It's so simple it must be wrong, and
I'd very much appreciate it if someone would explain why. 
My main bugaboo with pkgsrc is yours, too, probably: the tearing down of a
working system for the prospect of a better one. I'm still running Moz
1.0 and <blush> Gnome 1.2 because rebuilding is such a pain. I've been
thinking about ways to build packages in a separate location. Then, when
all is ready, swap in the new stuff. 
The installed locations of packages are controlled by:
 X11BASE Where X11 is installed on the system. 
 LOCALBASE Where non-X11 based packages will be installed. 
 PKG_DBDIR Where package installation is recorded. 
We can even ignore X11BASE if xpkgwedge is installed first. 
Suppose on a freshly installed box I set:
	LOCALBASE=/usr/pkg-2003Q4
	PKG_DBDIR=/var/db/pkg-2003Q4
and add two symlinks:
	ln -s $LOCALBASE /usr/pkg
	ln -s $PKG_DBDIR /var/db/pkg
It seems to me I can "make install" merrily with nary a soul minding. 
Suppose later I decide it's time to upgrade. Rather than updating in
place, I adjust:
	LOCALBASE=/usr/pkg-2004Q1
	PKG_DBDIR=/var/db/pkg-2004Q1
and rebuild everything from scratch (starting with xpkgwedge). When I'm
ready, I just update the symlinks and away we go. 
Like I said, this is easy. It's almost atomic. Why won't it work? 
The only thing I can see is that /etc (and maybe /var) might get modified.
 But that's very rare, and I bet there's some magical attribute I could
use to prevent writing to those places, handling them specially. 
Many thanks for your thoughts. 
--jkl