This subordinate charm is used to configure nrpe (Nagios Remote Plugin Executor). It can be related to the nagios charm via the monitors relation and will pass a monitors yaml to nagios informing it of what checks to monitor.
This charm can be attached to any principal charm (via the juju-info relation) regardless of whether it has implemented the local-monitors or nrpe-external-master relations. For example:
juju deploy ubuntu
juju deploy nrpe
juju deploy nagios
juju add-relation ubuntu nrpe
juju add-relation nrpe:monitors nagios:monitors
If joined via the juju-info relation the default checks are configured and additional checks can be added via the monitors config option (see below).
The local-monitors relations allows the principal to request checks to be setup by passing a monitors yaml and listing them in the 'local' section. It can also list checks that is has configured by listing them in the remote nrpe section and finally it can request external monitors are setup by using one of the other remote types. See "Monitors yaml" below.
If another subordinate charm deployed to the same principal has a local-monitors or nrpe-external-master relation then it can also be related to the local nrpe charm. For example:
echo -e "glance:\n vip: 10.5.106.1" > glance.yaml
juju deploy -n3 --config glance.yaml glance
juju deploy hacluster glance-hacluster
juju deploy nrpe glance-nrpe
juju deploy nagios
juju add-relation glance glance-hacluster
juju add-relation glance-nrpe:monitors nagios:monitors
juju add-relation glance glance-nrpe
juju add-relation glance-hacluster glance-nrpe
The glance-hacluster charm will pass monitoring information to glance-nrpe which will amalgamate all monitor definitions before passing them to nagios.
Check definitions can come from three places:
This charm creates a base set of checks in /etc/nagios/nrpe.d, including check_load, check_users, check_disk_root. All of the options for these are configurable but sensible defaults have been set in config.yaml. For example to increase the alert threshold for number of processes:
juju config nrpe load="-w 10,10,10 -c 25,25,25"
Default checks maybe disabled by setting them to the empty string.
In addition, if this charm detects the existence of cos integration, it will automatically disable all default checks.
Monitors passed to this charm by the principal charm via the local-monitors or nrpe-external-master relation. The principal charm can write its own check definition into /etc/nagios/nrpe.d and then inform this charm via the monitors setting. It can also request a direct external check of a service without using nrpe. See "Monitors yaml" below for examples.
This works in the same way as the Principal requested except the monitors yaml is set by the user via the monitors config option. For example to add a monitor for the rsyslog process:
juju config nrpe monitors="
monitors:
local:
procrunning:
rsyslogd:
min: 1
max: 1
executable: rsyslogd
"
If the nagios server is not deployed in the juju environment then the charm can be configured, via the export_nagios_definitions, to write out nagios config fragments to /var/lib/nagios/export. Rsync is then configured to allow a host (specified by nagios_master) to collect the fragments. An rsync stanza is created allowing the Nagios server to pick up configs from /var/lib/nagios/export (as a target called "external-nagios"), which will also be configured to allow connections from the hostname or IP address as specified for the "nagios_master" variable.
It is up to you to configure the Nagios master to pull the configs needed, which will then cause it to connect back to the instances in question to run the nrpe checks you have defined.
The list of monitors past down the monitors relation is an amalgamation of the lists provided via the principal, the user and the default checks.
The monitors yaml is of the following form:
# Version of the spec, mostly ignored but 0.3 is the current one
version: '0.3'
# Dict with just 'local' and 'remote' as parts
monitors:
# local monitors need an agent to be handled. See nrpe charm for
# some example implementations
local:
# procrunning checks for a running process named X (no path)
procrunning:
# Multiple procrunning can be defined, this is the "name" of it
nagios3:
min: 1
max: 1
executable: nagios3
# Remote monitors can be polled directly by a remote system
remote:
# do a request on the HTTP protocol
http:
nagios:
port: 80
path: /nagios3/
# expected status response (otherwise just look for 200)
status: 'HTTP/1.1 401'
# Use as the Host: header (the server address will still be used to connect() to)
host: www.fewbar.com
mysql:
# Named basic check
basic:
username: monitors
password: abcdefg123456
nrpe:
apache2:
command: check_apache2
Before a monitor is added it is checked to see if it is in the 'local' section. If it is this charm needs to convert it into an nrpe checks. Only a small number of check types are currently supported (see below) .These checks can then be called by the nagios charm via the nrpe service. So for each check listed in the local section:
- The definition is read and a check definition it written /etc/nagios/nrpe.d
- The check is defined as a remote nrpe check in the yaml passed to nagios
In the example above a check_proc_nagios3_user.cfg file would be written out which contains:
# Check process nagios3 is running (user)
command[check_proc_nagios3_user]=/usr/lib/nagios/plugins/check_procs -w 1 -c 1 -C nagios3
And the monitors yaml passed to nagios would include:
monitors:
nrpe:
check_proc_nagios3_user:
command: check_proc_nagios3_user
The principal charm, or the user via the monitors config option, can request an external check by adding it to the remote section of the monitors yaml. In the example above direct checks of a webserver and of mysql are being requested. This charm passes those on to nagios unaltered.
Supported nrpe checks are:
procrunning:
min: Minimum number of 'executable' processes
max: Maximum number of 'executable' processes
executable: Name of executable to look for in process list
processcount:
min: Minimum total number processes
max: Maximum total number processes
executable: Name of executable to look for in process list
disk:
path: Directory to monitor space usage of
custom:
check: the name of the check to execute
plugin_path: (optional) Absolute path to the directory containing the
custom plugin. Default value is /var/lib/nagios/plugins
description: (optional) Description of the check
params: (optional) Parameters to pass to the check on invocation
Supported remote types: http, mysql, nrpe, tcp, rpc, pgsql (See Nagios charm for up-to-date list and options)
By defining 'monitors' binding, you can influence which nrpe's IP will be reported back to Nagios. This can be very handy if nrpe is placed on machines with multiple IPs/networks.
The charm defines following actions:
list-nrpe-checks: gives a list of all the nrpe checks defined for this unit and what commands they use.run-nrpe-check: allows you to run a specified nrpe check and get the output. This is useful to confirm if an alert is actually resolved.ack-reboot: allows you to acknowledge a reboot alert. If you need to acknowledage all units, e.g.: in a power outage, you can disable and re-enable the reboot check instead.