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RE: Setting up service dependencies: msg#00402
network.nagios.user
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Subject: |
RE: Setting up service dependencies |
yeah,
I'm willing to deal with the fact that the host may not be really down if I'm
checking HTTP.
Your
example is similar to what I tried. But almost all my services use
hostgroup_name rather than host_name to keep things manageable. Otherwise I
would have over 500 service objects to manage. servicedependency doesn't seem to
work right when you substitute hostgroup_name for host_name like it works for
all other object definitions. I would have to create thousands of service
dependecies if I were to do everything on a host basis rather than hostgroup. Oh
well, but here's a vote for XML config files which would make automatic
generation of these files easier.
Jeff
It's not A Bad Thing per se; given the example of a host behind a
firewall with a hole at port 80 poked through it, it would certainly have
merit. But in the case where your webserver fails but, say, sshd is
still up, can the host be said to be down?
Just to say that I gave you a servicedependency example, here it
is:
define service{
host_name
itdmll01
use
icmp
service_description
NRPE check
contact_groups
linux-admins
check_command
check_nrpe!check_nrpe_status
}
define service{
host_name
itdmll01
use
icmp
service_description
Total Users
contact_groups
linux-admins
check_command
check_nrpe!check_users
}
define servicedependency{
dependent_host_name
itdmll01
dependent_service_description Total
Users
host_name
itdmll01
service_description
NRPE check
execution_failure_criteria
w,u,c
notification_failure_criteria
w,u,c
}
Explanation: "NRPE check" is the basic 'is NRPE up' check.
"Total Users" actually kicks off a plugin on the remote host. "Total
Users" is dependent on "NRPE check". If "Total Users" fails, it checks
to make sure that "NRPE check" is up/down. If the latter is down, that's
all I get alerted on. If it's still up, then I get alerted on the
former.
Does this help?
jc
I
think I found a workaround for this. For some servers, like webservers most
of the services are some form of HTTP request, so I changed the
check_command on the host to do a simple http request. If that fails, then
the host is considered 'down' rather than just using the standard ping
check. If this is 'bad' for some reason, please let me
know.
second question: is it possible to pass arbitrary ssh parameters
to check_ssh, like "-1" for ssh v1? Doesn't appear so, but maybe there's a
trick?
Jeff
I've looked at the examples that come with nagios and they don't
seem to address the problem of using hostgroups versus hosts. I'm not
using NPRE, but if you have examples using hostgroups, I'd love to see
them.
Jeff
That's different. You'll want to set up a
service dependency, of course.
Er... do you absolutely need to check for static
HTML? I mean, if the PHP fails because the webserver is
down.... Oh, unless you just want to be informed that there's a
PHP problem but that the server itself it still up. Okay, I can
see that.
I've set up various NRPE dependencies at our site,
so if you need a trivial example, I can post one to the list. Let
me know.
jc
That's good to know. I still have this issue though because I
have some tests that aren't going work if simpler tests fail. For
example, a simple test to see if a webserver can serve a static HTML
can fail, and if that's the case then checking to see if the webserver
will return a PHP page is obviously not going to work.
Jeff
I'm not sure why you're taking this
approach. Out of the box, Nagios will behave as you wish it
to.
If a service check fails, then a host check is
made. If the host check fails, it's flagged as down and,
depending on your particular configuration, you'll receive the
notification for the host being down, not for the N services you're
monitoring on that host. If the host check passes, then you'll
get an alert on the service.
jc
Hello all,
I'm trying to set up service
dependencies in Nagios. For example, I don't want alerts about an
HTTP service being down on a host if the host isn't
pingable.
So far, the only way I've found to do
this is to set it up for each host individually. That would be
difficult with the hundreds of hosts that my nagios is currently
monitoring.
I tried creating a servicedependency
object with a hostgroup_name and a dependent_hostgroup_name. This
seems to make each host in hostgroup_name dependent on EVERY host
in dependent_hostgroup_name. For example, if my hostgroup has 7
hosts in it, it seems it's making each of those 7 hosts dependent
on each other, making 7x7=49 dependencies. (Stragely, Nagios
reports 98 dependencies. Why 2x?)
Any suggestions on how to make a
service dependencies local to each host and not a group of hosts
without lots and lots of dependency objects?
Jeff
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