[collectd] collection4 nitpicking

[Trent W. Buck]

Trent W. Buck wrote:
> When I edit collection.conf, how do I tell c4 to reread it?
>
> I suppose it happens automatically after enough requests when apache
> kills the old c4 process and starts a new one, but I've simply been
> doing "pkill collection.fcgi", which is... suboptimal.

OK, I finally realized that as well as restarting the fcgi, I have to
delete the collection.json cache file.  No wonder I was getting so
confused -- during testing, I was (presumably) only getting the new
collection.conf once each time the .json expired (presumably at
Interval 60 or so).

Obvious in hindsight :-(

So I added these two.  The first works fine, the second gives strange
results because each line should pick up $TypeInstance, which will be
"error", "loop", or an IP address I don't know in advance.  I haven't
worked out how to add a "dynamic" set of <DEF>s, i.e. have it
automatically label the lines like "128.16.0.1" instead of "value3".

    <Graph>
      Host "/any/"
      Plugin "conntrack"
      PluginInstance ""
      Type "conntrack"
      TypeInstance ""

      Title "Connections (internet layer)"
      VerticalLabel "Connections"
    </Graph>

    <Graph>
      Host "/any/"
      Plugin "ntpd"
      PluginInstance ""
      Type "/any/"
      TypeInstance "/all/"

      Title "NTPd"
    </Graph>

While reading the rrdgraph manpage, I also realized that <DEF> stands
for "definition", in rrdgraph style.

The other plugins I'm collecting, that don't have pre-defined <Graph>
stanzas yet, appear to be:

    vmem
    thermal
    protocols
    cpufreq
    nfs
    irq
    uptime
    solos (in-house Exec graph of Solos ADSL card's SNR margins via /sys/)
    entropy
    mysql
    processes-foo (monitoring specific processes)
    network

I'll probably have a crack at defining useful graphs for these later
this week, although really I am supposed to be writing Threshold
configurations to replace our old nagios2 infrastructure (more on that
tomorrow, I hope).