Re: redo

[Jonathan de Boyne Pollard <J.deBoynePollard-newsgroups@NTLWorld.com>]

Lee Winter:
> One key component of an  effective startup process is dependency
> handling.  So why not look for one of the best as a model?  I
> suggest DJB's redo system.  It is excruciatingly simple.  But very
> effective. And it is the opposite of monolithic.

Is "practically nonexistent" the opposite of monolithic, now?  (-: He 
never actually published it, you know (although a few of his other 
unfinished works that did get published contain glimpses in their build 
systems).  The task of constructing and publishing working redo toolsets 
was left to Alan Grosskurth, Avery Pennarun, and some other bloke.

redo is a useful tool that can have a use in system initialization. 
Someone asked me an interesting question about /etc/rc.conf.local in 
FreeNAS recently and I came up with an interesting answer that made use 
of redo which I have to write up at some point.  But it's another tool 
in a good toolbox, not the whole of the toolbox.  Nor is it necessarily 
the starting point for everything that has the word "dependency" 
somewhere in its description.  I can think of three things in the 
various implementations of redo that will interact quite poorly with the 
notion of repeatably starting up daemons with controlled initial process 
states and dropped privileges: maintaining database and job control 
access, alternative routes, and what the process tree ends up looking 
like.  And that's skipping over the whole notion of shutdown.  There are 
ways to marry service dependencies with the 
the-filesystem-is-the-database paradigm, but one doesn't really start 
here to reach them.

Maybe Alan Grosskurth, Avery Pennarun, or that other bloke have written 
some tools for system and daemon management.

* 
http://homepage.ntlworld.com./jonathan.deboynepollard/FGA/introduction-to-redo.html
* http://homepage.ntlworld.com./jonathan.deboynepollard/Softwares/nosh.html