server-nagios ansible role

This is an ansible role to set up nagios on a network. The idea is to use ansible inventory and vars to "automatically" set up hosts and services in nagios.

The target network is 10-20 devices and 1-3 admins, not large scale enterprise.

Design decisions

• this is a stand-alone role

  Others part of ansible will have to handle firewalls, package management, users, logging and whatever else you want of a server.

  Currently, apache2 is installed as part of the role. This might change.

• ansible groups becomes nagios hostgroups

  Devices in a group will automatically be in a nagios group of the same name Groups named all and ungrouped are ignored by default.

• provisioning to nagios is independent of fact collection

  All the info that nagios needs are in group_vars and host_vars, so it is sufficient to have the devices in inventory.

• notifications use email

  Proper emailing must be set up on the system, e.g using dpkg-reconfigure exim4-config

• notification is specified per contact

  Default is to use email. A notify list containing X, Y and Z gets converted to notify-host-by-X, notify-host-by-Y and notify-host-by-Z, which must exist, probably defined in custom-objects.

• configurations are split into default, ansible and non-ansible.

  The configuration is default in /usr/local/nagios/etc. Main config file is nagios.cfg (ansible controlled) and the subdirectories contains other config. Path is specified using nagios_base_dir.

  ansible-hosts contains the autogenerated config by ansible.

  custom-objects contains whatever manual stuff the admin want also, like non-default commands and non-ansible hosts.

• role is usable out-of-the-box, ie. no config is need to have an minimal setup.

Setup

See tests directory for details

We download nagios from github and the version specified in nagios_version must match that.

Nagios plugins are also downloaded from github and nagios_plugins_version must match a version there.

Minimal config

The role may be used without setting any host_vars or group_vars. See test-defaults/test.yml for an example

So a playbook like this is minimum

- hosts: all

  roles:
  - {role: server-nagios, become: true }

This assumes that the roles is pulled to the directory roles/server-nagios.

Notifications will be minimal, localhost will have some checks, and every other device in inventory will be a host with no service checks.

Small example

• In the example the nagiosserver is called nagioshost and there is another host called otherhost

inventory

• the two servers are in the servers group and one in the otherservers group

[servers]
nagioshost
otherhostA

[otherservers]
otherhostB

playbook.yml

• in the playbook we define how to provision

- hosts: nagioshost

  roles:
  - { role: server-nagios, become: true }

# provision other hosts if applicable
#- hosts: otherhost?
#
#  roles:
#  - {}

Defining variables for the host groups

• one group called servers and another called otherservers

group_vars/all.yml or group_vars/all/nagios.yml

• define the users that will be referenced in notifications
• define contact info for the default nagiosadmin user
• Both users A and B will be notified by email (since it is default), and userA will also be notified using othermean.
• User A is in the admin group and will receive notification for that group

nagios_contacts:
  - name: userA
    mail: userA@somewhere
    notify:
      - email
      - othermean
  - name: userB
    mail: userB@somewhere

nagios_admin_group_contact: userA

group_vars/servers.yml or group_vars/servers/nagios.yml

• define who should be notified when something happens
• define the tests that are to be used for all groups. The text written will be used directly as check command. See the nagios documentation for details.

nagios_group_contacts:
  - userA
  - userB

nagios_group_tests:
  ping: "check_ping!100.0,20%!500.0,60%"
  ssh: check_ssh

group_vars/otherservers.yml or group_vars/otherservers/nagios.yml

• the group otherservers are not to be included in nagios
• hosts in the groups will, unless something else is defined in hostvars, be excluded from nagios.

nagios_exclude_group: True
nagios_exclude_host: True

Defining for the hosts

• host specific tests are not implemented yet

host_vars/nagioshost.yml or host_vars/nagioshost/nagios.yml

• userA is the owner and will be notified. Default owner is nagiosadmin.

nagios_host_owner: userA

nagios_admin_user: nagiosadmin
nagios_admin_pass: somepass

host_vars/otherhostA.yml or host_vars/otherhostA/nagios.yml

• userB is the owner and will be notified.
• Specific to otherhostA, HTTP will also be checked. Other checks from the group are still included.

nagios_host_owner: userB

nagios_host_checks:
  http: check_http