[gPXE] Setting delay time to boot

[Jonathan Andrews]

On Sun, 2010-03-28 at 12:31 +0200, Piotr Jaroszyński wrote:
> > Take a cluster booting after a power failure:
> >
> > waitfor DHCP_SERVER_IP  A_LATE_STARTING_SERVICE 0
> > dhcp net0
> > waitfor SAN_SERVER_IP A_LATE_STARTING_SERVICE 0
> > chain <some cryptic SAN rune>
> >
> > My only concern would be it would need to have an ASCII spin thingi or
> > some other indication that its not just locked up :-)
> >
> > Others might not agree that the logic is friendly or even that the idea
> > is good ?
> 
> Perhaps a command like "keeptrying <command> [<interval>]" would be
> more generic? It would just keep retrying <command> unless it succeeds
> every <interval> seconds. OTOH with commands returning whether they
> worked or not and conditionals it could be implemented as a simple
> loop.
> With it, your example could be implemented as:
> 
> keeptrying dhcp net0
> keeptrying chain <some cryptic SAN rune> 15
> 
> I think it more closely reflects what you are after. You don't really
> care whether A_LATE_STARTING_SERVICE is up, you just want to get your
> ip from dhcp and then boot from iscsi or something. (And btw. you
> can't do waitfor ip port w/o an IP address in the first place :)
> 

I was thinking more like a single global timeout variable, default is
zero (forever) but settable at any point and respected by each
operation.

dhcp net0
timeout 30s
chain http://ip:8080/some_boot_file
chain http://anotherip:8080/some_boot_file

But as I said, this adds fallbacks to every operation - could end up
with nobody sure how a box booted, or even worse any number of subtle
gotchas in scripting !


Cheers,
Jon