[mrtg] Centralize data

[Niall O'Reilly]

On 2 Mar 2012, at 19:46, Steve Shipway wrote:

> Yes, it is possible, and we do it here.  
> 
> The problem is that you need to use the absolute latest MRTG, and the Trunk version of RRDTool 1.4 in order to have the required functionality.  

	If you actually need centralized display, rather than centralized data,
	there are other ways to do it, which avoid these requirements.

	Both for historical reasons, and because some of the instrumentation
	we need is troublesome to implement centrally, we use a "portal"
	which presents MRTG data on several systems as a single web site.  
	This depends on a carefully-considered URL naming scheme and
	the use of ProxyPass and ProxyPassReverse directives in configuring
	the Apache HTTP server on the portal system.

	Some of our display pages juxtapose data which reside on more than
	one system.

	Here's a fragment from the httpd.conf on the portal system.
	As it happens, the target system mentioned is no longer in service.

<Location /mrtg/ch/servers/slievemann/>
    ProxyPass http://slievemann-ch-eth0.ucd.ie/mrtg/ch/servers/slievemann/
    ProxyPassReverse http://slievemann-ch-eth0.ucd.ie/mrtg/ch/servers/slievemann/
</Location>

	I hope this helps.

	Niall O'Reilly