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Hi Jano,
John Lukac wrote:
>
> Robert Nibali wrote:
> > Ok, the second thing you'd like to know is how to check the service
> > running on a realserver (please correct me if I'm wrong): I call this
> > healthchecking (commercial loadbalancer vendors tend to call it alike)
> > What you do here is: The loadbalancer runs a daemon that checks
> periodi-
> > cally all realservers services like for example http, telnet. This
> check
> > can be from poor-man solution (icmp) to highend (connect to webserver,
> > start a request to the database and verify it's content). Your daemon
> > then performes those checks agains all realservers and if a check
> fails
> > the realserver will be taken out. The check goes on and if the server
> > or service comes back, it will be inserted again into the table with
> > ipvsadm. NOTE: This works EXTREMELY well!!! Only negative aspect: You
> > have to write your own daemon.
>
> Several are availble, one in particular which comes to mind is, of
> course, Big Brother (www.bb4.org or .com or something). It even
> supports redundant monitoring, and services beyond the basics (e.g. ftp,
> http) can be monitored with some effort.
It's bb4.com and it's not quite what I tried to explain although you can
do it with this tool. Basically this tool like dozens of others of this
kind check services and /report/ it to one particular server (daemon).
This daemon/server can then, regarding its configuration, decide how to
alarm or show that something is not correct. However if you take f.e the
bigbrother tool you still have to write the hook to the ipvsadm userspace
tool. bigbrother knows absolutely nothing about ipvsadm and is useless.
Unfortunately the bigbrother API is rather complex to extend so this would
probably result in more work than rewriting the own daemon. On the other
hand, if everybody starts writing their own version of os monitoring tool
we end up with a bunch of such tools with minor difference. We also wrote
such a tool based on zope and different scanners for each purpose in a net ;)
Hope this is not too insulting and thank you for the link.
Best regards,
Roberto Nibali, ratz
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