RE: [Xen-API] xapi accepting commands before being fully up

[Dave Scott <Dave.Scott@xxxxxxxxxxxxx>]

Hi George,

...
> But it just seems
> logical to me that if there's a bunch of initialization to do, you
> should refuse / delay certain classes of queries until after it's done.
> 
> Anyway, that's my $0.02, I'll leave it with you guys. :-)

I agree this would be ideal. In fact we already have code to block master 
database lookups until the database state is considered ready -- we could 
probably do something similar for the CLI at least. The XenAPI handling is a 
bit complicated because some limited master <-> slave communication is needed 
in order to 'enable' a host.

Cheers,
Dave


>   -George
> 
> On 12/07/10 15:43, Anil Madhavapeddy wrote:
> > Xapi touches a file when it has finished starting up, based on the -
> writeinitcomplete command line flag passed to it.  In XenServer, that's
> defined in the startup script as /var/run/xapi_init_complete.cookie
> >
> > Might be better to monitor that file, rather than SSH (which is
> pretty unrelated to xapi, but I'm not sure monitoring 443 would work
> better as stunnel might come up quite early).
> >
> > -anil
> >
> > On 12 Jul 2010, at 15:34, George Dunlap wrote:
> >
> >> It seems that xapi is up and accepting commands before everything is
> actually ready yet.  I have a script that will wait for a host to boot
> by pinging and then testing listening on the ssh port; when it succeeds,
> the host should be up and ready.
> >>
> >> However, if I write a command that runs that script, and then
> immediately tries to start a VM on that host, I get this error message:
> >> ---
> >> There are no suitable hosts to start this VM on.
> >> The following table provides per-host reasons for why the VM could
> not be started:
> >>
> >> exile    : Cannot start here [Host disabled (use 'xe host-enable' to
> re-enable)]
> >> --
> >>
> >> Subsequent attempts succeed.
> >>
> >> It seems like xapi should either wait until all local hosts are up
> before accepting vm-start commands, or if they get a command that
> depends on certain hosts, it should wait for them to be enabled.
> >>
> >> I think if that's not easy to do, maybe a "wait-for-host-to-be-
> initialized" command... :-)
> >>
> >> -George
> >>
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> >>
> >
> 
> 
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