check_many plugin

Overview

This proposal is for a simple plugin wrapper allowing aggregation and serialisation of multiple checks.

Problem

There is no easy way to configure a single nagios service that aggregates multiple results together. Taking for example a standard "check_nagios" between servers, how can such checks be extended to cover additional components? Usually it involves writing a custom shell wrapper around them, of configuring all the checks separately and using check_cluster to aggregate them. There ought to be a better way...

Proposal

Written in C, check_many would be a fairly simple and fast solution for this issue. The idea is a plugin that takes checks commands from STDIN; one command per line. It would run them and aggregate them according to processing preferences as configures in the plugin arguments.

Check Options

The following options can be used to control plugin processing (grouped by category):

Command Parsing


-s, --shell=<always|never|auto>
Specify when a shell should be invoked for executing commands. "always" invokes the shell for every command, "never" forces commands to to executed directly, and "auto" (default) invokes the shell only is shell meta-characters are present in the check command.
Unless -d (--delimiter) is specified, any whitespace is used for separating arguments.

-d, --delimiter=CHARACTER
Delimiter to use for separating command arguments when shell is not used. Implies --shell=never and is mutually exclusive with any other shell option. Standard backslash escapes are allowed, except "\n".


Note: Should we allow strings as delimiters?

Processing Option


-P, --process=<all|first-fail|first-ok>
By default, all command are processed and the worst state is returned ("all"). "first-fail" stops at the first non-ok check and return it, while first-ok stops at the first successful check and return it. The latter two overrides --status and --output option and return the plugins's instead.

-f, --file=FILE
Read checks form FILE instead of STDIN


Output Options


--output=<normal|oneline|status&gt
"normal" outputs Nangios v3+ multi-line result, first line being a summary of the checks performed, "oneline" squeezes everything in a single line, and "status" returns only a status line". This option has no effect with --process=first-fail|first-ok


Note: How about allowing Nth result?

Examples

Aggregate multiple checks together:


echo -e "/path/check_http -H www.example.com\n/path/check_http -H www.example.com -p 443" | /path/check_many


Get list of checks from a file:

/path/check_many <~nagios/multiple_checks.txt
/path/check_many -f /home/nagios/multiple_checks.txt


Using a delimiter:

echo -e '/path/check_foo:-H:example.com\n/path/check_bar:-H:example.com:-s:$some string with "shell-intrepretable" characters;' | /path/check_many -d: