Re: Quick cfengine poll...

[Christopher Browne]

On Mon, 26 Mar 2001 16:51:32 +0200, the world broke into rejoicing as
"Denis GERMA" <denis.germa@cstelecom.com>  said:
> I appreciate cfengine as a tool to distribute files to sets of
> machines.  I presently manage a set of around 80 machines.

Frankly, if the point is of "distributing files," I'd think rsync to
be somewhat preferable.  cfengine becomes useful when you've got more
to do than that...

> There are some concepts I did not understand in your conversation :
> -------------------------------------------------------------------------=

> a- What do you mean exactly with "e.g. by distributing everything as
> master files"

> Do you mean there should not exist one set of "master files" ?  Or
> Do you mean that the distribution should be done from a central
> server, relayed by intermediary servers which get there files from
> the central server ?

> ---In other term are you speaking of performance, or configuration
> files structures ?

The latter (relayed by intermediary servers) seems more sensible; it
doesn't make sense for 5000 machines to all poll one system to get
configuration, potentially overloading the one server, when adding a
bit more configuration complexity allows farming out the work to a set
of "second tier" servers in much the same way that people use FTP
"mirrors" to take the load off the central server.

> b- I do not understand what you mean by "They're still thinking
> shell or perl, and don't understand agent based control systems."
> Could you explain ?  or Is there a document or book explaining the
> good way of thinking with cfengine ?

The world could use disclosure of some reasonably complex cfengine
configurations; there is interesting stuff in the cfengine
documentation, but it's probably not enough to satisfy those that
don't "get it."

The "tutorial" document probably needs to have an extended cfd
example.  

It also might benefit from an example of how to have a 3-tier cfengine
configuration, with a central server and then a set of "assistants"
that the bottom tier servers hit on to get their configuration
updates.
--
(concatenate 'string "cbbrowne" "@acm.org")
http://vip.hex.net/~cbbrowne/resume.html
"For systems, the analogue of a face-lift is to add to the control
graph an edge that creates a cycle, not just an additional node."
-- Alan Perlis