[ClusterLabs] Insert delay between the statup of VirtualDomain

[Oscar Segarra]

Hi Dejan,

In my environment, is it possible to launch the check from the hypervisor.
A simple telnet against an specific port may be enough tp check if service
is ready.

In this simple scenario (and check) how can I instruct the second server to
wait the mysql server is up?

Thanks a lot

El 1 mar. 2017 1:08 p. m., "Dejan Muhamedagic" <dejanmm at fastmail.fm>
escribió:

> Hi,
>
> On Sat, Feb 25, 2017 at 09:58:01PM +0100, Oscar Segarra wrote:
> > Hi,
> >
> > Yes,
> >
> > Database server can be considered started up when it accepts mysql client
> > connections
> > Applications server can be considered started as soon as the listening
> port
> > is up al accepting connections
> >
> > ¿Can you provide any example about how to achieve this?
>
> Is it possible to connect to the database from the supervisor?
> Then something like this would do:
>
> mysql -h vm_ip_address ... < /dev/null
>
> If not, then if ssh works:
>
> echo mysql ... | ssh vm_ip_address
>
> I'm afraid I cannot help you more with mysql details and what to
> put in '...' stead above, but it should do whatever is necessary
> to test if the database reached the functional state. You can
> find an example in ocf:heartbeat:mysql: just look for the
> "test_table" parameter. Of course, you'll need to put that in a
> script and test output and so on. I guess that there's enough
> information in internet on how to do that.
>
> Good luck!
>
> Dejan
>
> > Thanks a lot.
> >
> >
> > 2017-02-25 19:35 GMT+01:00 Dejan Muhamedagic <dejanmm at fastmail.fm>:
> >
> > > Hi,
> > >
> > > On Thu, Feb 23, 2017 at 08:51:20PM +0100, Oscar Segarra wrote:
> > > > Hi,
> > > >
> > > > In my environment I have 5 guestes that have to be started up in a
> > > > specified order starting for the MySQL database server.
> > > >
> > > > I have set the order constraints and VirtualDomains start in the
> right
> > > > order but, the problem I have, is that the second host starts up
> faster
> > > > than the database server and therefore applications running on the
> second
> > > > host raise errors due to database connectivity problems.
> > > >
> > > > I'd like to introduce a delay between the startup of the
> VirtualDomain of
> > > > the database server and the startup of the second guest.
> > >
> > > Do you have a way to check if this server is up? If so...
> > > The start action of VirtualDomain won't exit until the monitor
> > > action returns success. And there's a parameter called
> > > monitor_scripts (see the meta-data). Note that these programs
> > > (scripts) are run at the supervisor host and not in the guest.
> > > It's all a bit involved, but should be doable.
> > >
> > > Thanks,
> > >
> > > Dejan
> > >
> > > > ¿Is it any way to get this?
> > > >
> > > > Thanks a lot.
> > >
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