Network scripting

Network scripting

[Richard A Downing FBCS]

In <http://smarden.org/pape/djb/daemontools/noinit.html>, Gerrit suggests:

"...why not think about eth0 as a service? Let a supervisor garantee the state
of eth0, take it like any other service."

Having moved everything else over to runit, I want to replace my sysvinit
scripts that bring up the ethn interfaces. But I have to admit that I can't
quite see how to do it.

Does anyone have a solution they could share?

-- 
Richard A Downing FBCS http://www.109bean.org.uk/
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Re: Network scripting

[Scott Gifford]

Richard A Downing FBCS <richard@109bean.org.uk> writes:

> In <http://smarden.org/pape/djb/daemontools/noinit.html>, Gerrit suggests:
> 
> "...why not think about eth0 as a service? Let a supervisor garantee the state
> of eth0, take it like any other service."
> 
> Having moved everything else over to runit, I want to replace my sysvinit
> scripts that bring up the ethn interfaces. But I have to admit that I can't
> quite see how to do it.
> 
> Does anyone have a solution they could share?

I do exactly this for eth1 on my fileserver.  Here's my run file:

    #!/bin/sh
    
    exec 2>&1
    
    HOSTNAME=CC312669-A
    DEVICE=eth1
    
    exec /usr/local/sbin/dhcpcd -h "$HOSTNAME" -d -v -a -m "./conf/rc" "$DEVICE"

It's very simple, and it's intuitive (to me anyways) to say svc -d
/service/eth1 to shut down my network connection, svc -t to restart
the DHCP server, etc.

I'm not sure how much sense it would make to use supervise to manage
a static ethernet connection.  The only way I can think of would be to
use a script that set up the interface, then just slept until it
received a TERM signal, at which point it shut the interface down.
Seems kinda silly, but workable.

----ScottG.

Re: Network scripting

[Charlie Brady]

On Sun, 1 Feb 2004, Scott Gifford wrote:

> Richard A Downing FBCS <richard@109bean.org.uk> writes:
> 
> > In <http://smarden.org/pape/djb/daemontools/noinit.html>, Gerrit suggests:
> > 
> > "...why not think about eth0 as a service? Let a supervisor garantee the state
> > of eth0, take it like any other service."
> > 
> > Having moved everything else over to runit, I want to replace my sysvinit
> > scripts that bring up the ethn interfaces. But I have to admit that I can't
> > quite see how to do it.
> > 
> > Does anyone have a solution they could share?
...
> I'm not sure how much sense it would make to use supervise to manage
> a static ethernet connection.  The only way I can think of would be to
> use a script that set up the interface, then just slept until it
> received a TERM signal, at which point it shut the interface down.

Most easily done with runit rather than daemontools. You'd use 'finish' to 
bring the interface down. For the run script, compile this as "pause":

main()
{
   exit(pause());
}

and have a run script which does:

#! /bin/sh
modprobe eth0
# check preconditions here and wan and exit if not met
ifconfig ...
exec /usr/local/bin/pause

> Seems kinda silly, but workable.

It might make sense if the interface might be DHCP or static configured 
from time to time, and you want a consistent design.

--
Charlie

Re: Network scripting

[Thomas Schwinge]

On Sun, Feb 01, 2004 at 09:15:39PM -0500, Charlie Brady wrote:
> For the run script, compile this as "pause":
> 
> main()
> {
>    exit(pause());
> }

You could also use <URL:http://multivac.cwru.edu./runwhen/rw-sleep/>.

> and have a run script which does:
> 
> #! /bin/sh
> modprobe eth0
> # check preconditions here and wan and exit if not met
> ifconfig ...
> exec /usr/local/bin/pause

[...]
exec rw-sleep -

Regards,
 Thomas