Nagira configuration

Run-time configuration

Nagira run-time environment configured by adjusting settings in config/defaults.rb and config/environment.rb files. In most cases defaults.rb file should not be changed, usually only editing environment.rb file is enough or even this in not required. Most defaults provided in defaults.rb and environment.rb will work for majority of users and don't need change. Anyway, recommendations below are for configuring Nagira.

File config/defaults.rb defines configuration hash DEFAULT, it sets attributes settings for Sinatra. Files defaults.rb and environment.rb use different syntax for configuration: former one uses hash assignment, while latter one uses Sinatra 'set <variable>' syntax.

Environment variables

See comments in config/nagira.defaults file for environment variables that Nagira understands. This file is copied to system defaults area during installation. Bu adjusting values in this file you can change Nagira installation.

The same variables can be set in the shell if you are using Nagira on command line.

Some of the configuration examples given below can be changed either in source of Nagira or by environment variable.

Per-environment configuration

All settings can be configured either globally or for specific environment (development, production). If configuration block does not have environment name, it is applied for the whole application, otherwise it is only for specific environment.

  configure do 
    set :format, :json
  end


  configure :development, :test do 
    set :nagios_cfg, "#{dir}/nagios.cfg"
  end

For more details please see Sinatra configuration documentation.

Nagios files location

Location of all Nagios files and data files are automatically detected by parsing nagios.cfg file on start. Therefore you only need to point Nagira to this file location. Value for the search directories is set in ruby-nagios module defaults (starting from Nagira version > 0.2.1) and it is:

    :nagios_cfg_glob => ENV['NAGIOS_CFG_FILE'] || 
    [
     "/etc/nagios*/nagios.cfg", 
     "/usr/local/nagios/etc/nagios.cfg"
    ]

If you are using some standard distribution of Nagios -- for example RedHat/CentOS RPM or Debian/Ubuntu dpkg -- chances are your nagios.cfg file is in /etc/nagios3 or /etc/nagios directory. In this case Nagira will be OK with default configuration.

However, if this is not the case, please set file location as in the example below or override by setting variable NAGIOS_CFG_FILE in the shell.

Example configuration

Configure location of main configuration file for production:

    configure :production do
       set :nagios_cfg, "/usr/local/nagios/etc/nagios.cfg"
    end

Default HTTP output format

Nagira supports multiple output formats: XML, JSON, YAML. Default output format is defined by settings.format Sinatra attribute. It is configured in config/defaults.rb as

    set :format, :json

File parsing time interval

By default Nagios data files are not parsed on each HTTP request, instead they are parsed only if file was modified more than N seconds ago. This is configured by Sinatra's setting ttl.

    DEFAULT = {
        ...
        :ttl => 60
        }

Note :ttl value can only be set in config/defaults.rb but not in config/environment.rb

Background parsing

When on user request Nagira needs to parse status.dat file (when :ttl time passed) for large files there could be significant delay in sending data back to user. On average these delays will happen every :min_parse_interval seconds.

If you want to prevent such delays responding to user requests, it is possible to start background loading and parsing status.dat file on regular intervals in separate thread.

For this set value of :start_background_parser to true and :ttl to at least 1 sec (or more).

    DEFAULT = {
        ...
        :ttl => 60
        :start_background_parser => true
        }

Note Same as :ttl above value of :start_background_parser can only be set in config/defaults.rb but not in config/environment.rb

Verifying your configuration

There is a RSpec file that allows to check your current configuration. It checks whether your Nagios files exist and can be parses by the Nagira.

Configuration checker is environment dependent. To check files for particular environment run check as:

    RACK_ENV=<environment> rspec -fd spec/00_configuration_spec.rb

In development and test (by default) it will check presence of files under ./test/data sub-directory. In production it checks actual Nagios files and validity of files in your Nagios installation.

With no errors check should produce output as following: