Ansible Role: Nagios

Installs Nagios, NRPE (both client and server), and configures Nagios automatically based on Ansible's existing inventory of hosts. The goal is to have a complete Nagios monitoring system in a single Ansible role, and without too much manual configuration required.

Prerequisites

Make sure that DNS or /etc/hosts name resolution is working. For example that you can ping web3 at web3.example.com. Email is a recommended prerequisite, with choices of Exim, Postfix, and others.

Role Variables

All the variables in the defaults/ directory may be overridden or changed.

Contacts/Users:

Add users who should be allowed to login to the Nagios web GUI in the nagios_users variable:

nagios_users:  
  - user: nagiosadmin  
    pass: Password1change  
    email: nagiosadmin@example.com

Another and better way to add both nagios contacts and nagios admins is the users variable, compatible with https://github.com/mivok/ansible-users

This playbook will look for users in the sysadmin group and those will become nagios admins.

Create the users var, a good place is group_vars/all. Here is an example.

users:  
  - username: foo  
    name: Foo Barrington  
    groups: ['sysadmin']  
    uid: 1001  
    ssh_key:  
      - "ssh-rsa AAAAA.... foo@machine"  
      - "ssh-rsa AAAAB.... foo2@machine"  
    htpasswd: $apr1$SheSL4Et$xry6RljdWWvUVrh42s7OA0  
    nagios:  
      pager: "nagiosadmin_pager@example.com"  
      email: "nagiosadmin@example.com"  

Where did that htpasswd value come from? Generate the htpasswds manually, and then paste them into users.

$ htpasswd -n mario  
mario:$apr1$SheSL4Et$xry6RljdWWvUVrh42s7OA0  

You must configure at minimum one sysadmin user, as just explained, or nagios contacts won't work.

Nagios Commands:

The nagios commands are in the nagios_commands variable, see defaults/main.yml. You can add more commands by adding to, or overriding, the variable.

Nagios Services:

The nagios services are currently in the "checks" per hostgroup in nagios_host_groups, see defaults/main.yml. You can add more services by adding to, or overriding, the variable.

Service checks per host are handled similarly in the nagios_hosts variable in defaults/main.yml.

Nagios Hosts:

Ansible hosts in the all group are converted to nagios monitored hosts. No configuration required.

Nagios Hostgroups:

Ansible groups are converted to nagios hostgroups. No configuration required.

Skipping Hosts and Hostgroups

The following values are set in defaults/main.yml :

nagios_hosts_ignore: ""
nagios_groups_ignore: ""

They can be overridden to include Hosts or Hostgroups that should be skipped entirely. Examples:

nagios_hosts_ignore:
  - host1_skip_this_host
nagios_groups_ignore:
  - hostgroup_dev_to_skip
  - and_this_one

This determines which hosts the nagios server will ignore/skip, because these hosts will be excluded from the configs.

Another consideration is whether the ansible playbook should run on all servers. The example playbook default.yml has - hosts: all, which installs the nagios client on all known servers. You could adjust your top-level playbook and set a different hosts: directive. However it's probably fine to install the monitoring client on all servers.

Example Playbook

Refer to default.yml in the root of this role.

To install the client:

  roles:   
    - { role: 'sdarwin.nagios', run_nagios_client: true }  

To install the server:

   roles:  
    - { role: 'sdarwin.nagios', run_nagios_server: true }   

Add nagios servers to the monitoring-servers group in the Ansible inventory. Example:

[monitoring-servers]  
monitor.example.com  

The nagios URL will have this format: http://monitor.example.com/nagios/

License

BSD

Author Information

By Sam Darwin, 2016. Based on pre-existing roles, see ACKNOWLEDGEMENTS.md file. Feedback and bug reports welcome.