Install the check_mk Agent

Check_MK is an extension to the Nagios monitoring system that
allows creating rule-based configuration using Python and
offloading work from the Nagios core to make it scale better,
allowing more systems to be monitored from a single Nagios server.

This patch provides an element to install the agent along with the
logwatch plugin to alert on logging events.  Port 6556 is also
opened in the firewall to allow an icinga server running check_mk
to connect.

More information on check_mk can be found at
http://mathias-kettner.com/check_mk.html

Change-Id: Ibc93bbb1f99efdde2792ece63f5cf332a2edddb7

elements/check_mk-agent/README.md

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+Install the check_mk monitoring client from the distribution's repositories.
+
+http://mathias-kettner.com/check_mk.html
+
+This element only installs the client and configures IPTables to allow traffic to it.
+
+If you wish to configure the server, please include the check_mk-server element on your
+icinga server.

elements/check_mk-agent/element-deps

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+iptables
+os-refresh-config
+os-svc-install

elements/check_mk-agent/install.d/05-check_mk-agent

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+#!/bin/sh
+
+# install check-mk-agent and the logwatch plugin
+
+set -eu
+set -o xtrace
+
+install-packages xinetd check-mk-agent check-mk-agent-logwatch
+# check_mk is disabled by default so we need to enable it here
+sed -i "s/\tdisable        = yes/\tdisable        = no/g" /etc/xinetd.d/check_mk
+
+os-svc-enable -n xinetd

elements/check_mk-agent/os-refresh-config/pre-configure.d/97-check-mk-agent-iptables

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+#!/bin/sh
+
+# configure the IPTables rules required for check_mk
+
+set -eu
+
+add-rule INPUT -p tcp --dport 6556 -j ACCEPT