[Users] HOWTO: Propagate VE0 (Host) Hostname into VE's ?

[Michael Stauber]

Hi Robert,

> I'm looking for a way to propagate the hostname of the VE0 a VE is
> running on (aka "The Host") into the VE environments (e.g. VE100).
>
> Is there any "start/stopp" script that I can hook into that is
>
> A) executed on the HOST not within the VE
>  and
> B) knows the "private dir" of the VE that is startet ?
>
> Or is there any other way to propage that hostname into VE's ?

If you have all VE's in /vz/private/, then you can of course "guess" that the 
private directory of the VE is /vz/private/<VPSID>/

The VPSID can be determined from inside a VE by looking at 
/proc/user_beancounters, which shows the VE at the beginning of the line where 
the kmemsize is reported.

I haven't found a way to determine the hostname of the master node from inside 
a VE. But if I had to have that info inside a VE, I'd probably set up a 
cronjob for that - similar to this:

-------------------------------------------------------------------------------------------------
#!/usr/bin/perl

if ( -d "/vz/private") {
    system("/usr/sbin/vzlist --no-header --output veid |  awk '{print \$1}' > 
/tmp/cronve-list");
    open(G, "/tmp/cronve-list");
    while ($line = <G>) {
        chomp($line);
        next if $line =~ /^\s*$/;               # skip blank lines

        if ($line =~ /^([0-9]\w*)/) {
            $VPS_ID = $line;
        }

        if ($VPS_ID != 0) {
                $master = `uname -n`;
                system("/bin/echo $master > /vz/private/$VPS_ID/etc/master");
        }
    }
    close (G);
    system("/bin/rm -f /tmp/cronve-list");
}
-------------------------------------------------------------------------------------------------

It is a bit more complicated than needed as my source for it does other things 
as well. This one here just stores the output of "uname -n" into the 
/etc/master in all VE's.

-- 
With best regards

Michael Stauber