Add custom variables to perfdata

[adrianlzt]

With these changes custom variables are now added to the perfdata.

Could be useful to other metric consumers to handle the data according to these variables.

Example ouput for a service with a custom variable owned by a host with two custom variables:

DATATYPE::SERVICEPERFDATA    TIMET::1486054220       HOSTNAME::webserver-1        SERVICEDESC::cpu    SERVICEPERFDATA::cpu_user=0%;70;90      SERVICECHECKCOMMAND::check_nrpe!cpu  SERVICESTATE::0 SERVICESTATETYPE::1
SERVICEINTERVAL::1.000000
_SERVICECHECK_NAME::check_cpu.sh
_HOSTPROJECT::camaleon
_HOSTDATABASE::atdb1

[sni]

This sounds like a good idea. However, i am a bit concerned about the change in format. Before this change, the perfomance data was a single line of tab separated text. Custom Variables are now added with newlines. This might break current performance data consumers. Also this patch potentially increases the payload a lot when having huge custom variables. So i think it would be good to make it optional. Or it would be nice to define a few custom variables which should be exported. Finally, if we could add a custom prefix to the export, ex. Nagflux could directly add custom variables as tags or values into the influxdb (https://github.com/Griesbacher/nagflux/commit/7c28bcf6a1df7ee38fb6042ddd06ce8fff80540e#diff-4ac32a78649ca5bdd8e0ba38b7006a1eR3)

Thinking about it, adding a "perfdata template" setting would solve all those issues with a single setting.

[adrianlzt]

I have used newlines because I saw it was already used:

"HOSTSTATETYPE::%d\n"
"HOSTINTERVAL::%f\n\n",

Thanks for the pointer to nagflux, I was starting to develop something similar. But it doesn't solve my problem neither. I want to send each metric to a different influxdb database selected by a host custom variable (_HOSTPROJECT).

What's the idea with "perfdata template"?

[sni]

What's the idea with "perfdata template"?

Something like the service_perfdata_file_template and host_perfdata_file_template option in Nagios/Icinga. Should be even possible to reuse the parse/expand functions from nagios/icinga for that since mod-gearman runs in the same memory.

[sni]

please reopen if its still relevant.