Re: [Xen-users] Monitoring Xen via Nagios

[Adam Goryachev <mailinglists@xxxxxxxxxxxxxxxxxxxxxx>]

On 17/07/2016 14:56, Jason Long wrote:
> I installed NRPE and my problem is that I don't know how can I define my server 
> and... to Nagios.
Please don't top post.

I think your issues at the moment are how to use Nagios, and have 
nothing to do with Xen. It would be best if you review the Nagios 
documentation, and/or discuss any issues with the Nagios mailing 
list/forums/etc.
When you reach the stage where you are having Xen specific monitoring 
requirement to add to Nagios, then you may need to come back here to 
discuss further.
> On Sunday, July 17, 2016 12:15 AM, Simon Hobson <linux@xxxxxxxxxxxxxxxx> wrote:
> JP Pozzi <jpp@xxxxxxxxxxxxxxxxxx> wrote:
>
> > You will have to learn things about Nagios :
> > - Nagios has to know about the hosts you want to monitor
> > - Nagios has to know what services yuo will monitor on every host
> > So you will have to describe all your hosts and services plus the limits
> > (warning or critical) for everything.
> Beat me to it ...
>
> To give the OP a bit of a starter ...
> Typically you will designate one system to do your monitoring - this does not 
> have to be one of your Xen hosts. In my case I run a dedicated machine for 
> this, but you could run it as a Xen guest with the obvious limitation that if 
> the host goes down then so does the monitoring.
>
> The base install of Nagios will probably only be set to monitor the local 
> machine (CPU load, RAM usage, logged in users). You need to define anything you 
> want monitoring - and it's a really good idea to see what templates can do for 
> you. Don't worry too much at the beginning - just experiment a bit, and be 
> prepared to undo stuff and do it a different way as you get the hang of it.
>
> To monitor anything but the local machine, means doing stuff across the network. A simple 
> "is this host there" can be done with ping (as long as ping responses aren't 
> turned off or firewalled). For stuff on the local network, it's also possible to monitor 
> ARP mappings (IIRC I had to write my own plugin for this) - not really useful for most 
> networks, but I do it on our hosting setup so I can detect various things, not least, 
> when someone sets up a device with a duplicate IP address.
>
> You can also monitor services (eg http and smtp) to detect if a remote service 
> is down.
>
> Beyond that, you need to "do stuff" remotely - and there are two main ways to 
> do that.
>
> One is to use SNMP - basically, if the device does SNMP and you know the right 
> OID to use, you can monitor anything covered by the SNMP agent on the device. 
> That could be detecting a link down on a switch, or the operating mode of a 
> UPS, or ...
>
> For "computers", you can also install NRPE - Nagios Remote Plugin Execute. 
> Basically a remote tool which can run Nagios plugins on the target device and return the 
> results. Typically (the safe way) you pre-define everything on the remote device, but 
> it's possible (at the cost of exposing a potential security hole) to pass parameters to 
> the NRPE service - allowing arbitrary plugin execution (the security hole being the 
> possibility of arbitrary remote code execution if you don't secure the communications 
> channel).
>
> So I would start with the basics.
> Get Nagios running and check that the builtin checks are working.
> Add some hosts (your Xen hosts, and some guests), and define some services - 
> ping is a basic one, after that SMTP for mail servers, HTTP for web servers, 
> and so on. It's possible to do a lot of monitoring of your Xen system simply by 
> monitoring the guests as though they were standalone machines - if they are 
> there on the network, then they are running !
> If you wanted more detailed monitoring, then you'd be looking at setting up 
> NRPE or SNMP on the Xen hosts and/or Guests. Eg, if you want to monitor disk 
> space on a guest, use SNMP or NRPE on the guest to do that.
>
> Just don't try and do everything at once. Get some basics working, and go from 
> there.
>
>
>
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