Alternative modules/blacklist/config check arguments syntax

[MarioSteinitz]

This is a suggestion to improve usability of the check_php's plugin for Icinga2 users:

Whereas the startup and update checks work as expected and can be configured easily as custom check command, it proves almost impossible to creating a working CheckCommand definition for module, blacklist and config checks without loads of custom programming and workarounds. An argument can easily be created with multiple occurrences, but then it can only have one value, not two or three.

Therefore, it is desirable to having an option telling the script, that the multi-argument options are concatenated using a divider char (e.g. |) .

Then the command

$ ./check_php -m "mysql" "e" -m "intl" "w"

could be aliased by

$ ./check_php -d -m "mysql|e" -m "intl|w"

Or setting checks like

$ ./check_php -c "memory_limit" "256M" "w" -c "opcache.enable" "1" "w"

could be aliased by

$ ./check_php -d -c "memory_limit|256M|w" -c "opcache.enable|1|w"

Which is far easier to achieve using default commands / arguments in Icinga2.

[cytopia]

I didn't really understand the current problem without the delimiter.
What in this line is causing a problem for Icinga2?

$ ./check_php -c "memory_limit" "256M" "w" -c "opcache.enable" "1" "w"

[MarioSteinitz]

The issue is, that with Icinga2 there is kind of a default check plugin wrapper with standardized (named or unnamed) configurable arguments that can be used to integrate custom check plugins. Composing the plugin call in the old-fashioned way (simply concatenating the command call manually) is possible, but highly discouraged.

The arguments of the check command can be named or unnamed, repeating, or single, and support one value each. But they do not support repeating named arguments with two or three associated values. So we could either make the e.g. three values of a config check one value by concatenating them, or we'd have to create a dirty workaround (custom functions/macros/manually creating the check call/...).

The suggested delimiter option avoids this. You can now just use the default check command wrapper of Icinga2 (or by omitting the delimiter argument, older Icinga/Nagios implementations).

Some more reading:
https://www.icinga.com/2015/10/28/understanding-commands-in-icinga-2/
https://www.icinga.com/docs/icinga2/latest/doc/09-object-types/#objecttype-checkcommand
The interesting part is the 'arguments'. Which - in case of module and config checks - are repeatable. You may also compare with our example Icinga2 config added to the README.md in our commit(s) for Issue #2. The service template of HOSTED-POWER will not work in any way for modules/blacklist/config checks without the delimiter. It only works for update and startup checks.