Class: NagiosHerald::Helpers::GangliaGraph

Inherits:
Object
  • Object
show all
Includes:
Logging
Defined in:
lib/nagios-herald/helpers/ganglia_graph.rb

Instance Method Summary collapse

Methods included from Logging

#configure_logger_for, #logger, #logger_for

Constructor Details

#initialize ⇒ GangliaGraph

Public: Initialize a GangliaGraph helper object.

Returns GangliaGraph helper object.



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# File 'lib/nagios-herald/helpers/ganglia_graph.rb', line 11

def initialize
  @ganglia_base_uri = Config.config['servers']['ganglia']
end

Instance Method Details

#get_cluster_name_for_host(host) ⇒ Object

Public: Get the Ganglia cluster name for a given host. So, if you’re still reading this and you use Chef, I recognize that you may not store the Ganglia cluster name as a node attribute. If you do, it’s probably not called ‘cluster_name’…

host - The name of the host whose Ganglia cluster name we need to look up.

Returns the Ganglia cluster name for the host.



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# File 'lib/nagios-herald/helpers/ganglia_graph.rb', line 43

def get_cluster_name_for_host(host)
  return nil unless load_knife_config
  query = Chef::Search::Query.new
  # we're only expecting a single node to be returned --> make sure it's the case!
  chef_node = query.search('node', "fqdn:#{host}").first.first
  chef_node.ganglia.cluster_name
end

#get_ganglia_url(cluster_name, host, metric, range) ⇒ Object

Public: Generate the URL required to download a graph of the require metric

cluster_name - The Ganglia cluster this node belongs to. host - The hostname of the node we need a metric for. metric - The name of the Ganglia metric we need. range - The time period we expect the metric to cover.

Example

get_ganglia_url("Web", "web0001.example.com", "part_max_used", "1day")

Returns a full Ganglia URL defining the metric graph to download



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# File 'lib/nagios-herald/helpers/ganglia_graph.rb', line 63

def get_ganglia_url(cluster_name, host, metric, range)
  return "http://#{@ganglia_base_uri}/graph.php?&c=#{cluster_name}&h=#{host}&m=#{metric}&r=#{range}&z=medium"
end

#get_graphs(hosts, metric, path, range) ⇒ Object

Public: Retrieve the Ganglia graphs we desire

hosts - An array of hosts for which to retrieve metrics. metric - The name of the Ganglia metric we need. path - The local path on the host running nagios-herald under which image

files will be temporarily generated.

range - The time period we expect the metric to cover.

Example

get_graphs([web0001.example.com], "part_max_used", "/tmp/img1234", "1day")

Returns the local paths of all downloaded images to be attached/inlined with a message.



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# File 'lib/nagios-herald/helpers/ganglia_graph.rb', line 80

def get_graphs( hosts, metric, path, range )
  # strip the trailing slash (if it exists) so the components of image_name are clear
  path = path.sub(/\/$/, "")
  image_paths = []
  hosts.each do |host|
    cluster_name = get_cluster_name_for_host(host)
    url = get_ganglia_url(cluster_name, host, metric, range)
    image_path = "#{path}/#{host}-#{metric}.png"
    success = NagiosHerald::Helpers::UrlImage.download_image(url, image_path)
    if success
      image_paths.push( image_path )
    else
      logger.warn("No Ganglia graph found for '#{host}' (cluster: '#{cluster_name}') - '#{metric}' in '#{range}'")
    end
  end
  return image_paths
end

#load_knife_config ⇒ Object

Public: Loads a Chef knife config. I recognize not everyone uses Chef, or any CM for that matter. Still, I like having this example here.

Returns true/false depending on whether a Chef knife config was loaded.



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# File 'lib/nagios-herald/helpers/ganglia_graph.rb', line 20

def load_knife_config
  return @knife_config_loaded unless @knife_config_loaded.nil?

  knife_config_file = Config.config['knife_config'] ? Config.config['knife_config'] : '~/.chef/knife.rb'
  knife_config_file = File.expand_path(knife_config_file)
  if !File.exist?(knife_config_file)
    logger.warn("Knife config file not found (#{knife_config_file})")
    @knife_config_loaded = false
  else
    Chef::Config.from_file(knife_config_file)
    @knife_config_loaded = true
  end
  @knife_config_loaded
end