add option in datadog_agent to extract hostnames

Fixes #160.

This option is a string regex which can be enabled and used to extract
the hostname from puppet hostname strings with a capture group.
It is useful for people that have specific puppet hostnames and that
would like to sanitize them before reporting those in Datadog.

lib/puppet/reports/datadog_reports.rb

@@ -14,6 +14,14 @@
   config = YAML.load_file(configfile)
   API_KEY = config[:datadog_api_key]
 
+  # if need be initialize the regex
+  HOSTNAME_EXTRACTION_REGEX = config[:hostname_extraction_regex]
+  begin
+    HOSTNAME_EXTRACTION_REGEX = Regexp.new HOSTNAME_EXTRACTION_REGEX unless HOSTNAME_EXTRACTION_REGEX.nil?
+  rescue
+    raise(Puppet::ParseError, "Invalid hostname_extraction_regex #{HOSTNAME_EXTRACTION_REGEX}")
+  end
+
   desc <<-DESC
   Send notification of metrics to Datadog
   DESC
@@ -38,6 +46,12 @@ def pluralize(number, noun)
   def process
     @summary = self.summary
     @msg_host = self.host
+    unless HOSTNAME_EXTRACTION_REGEX.nil?
+      m = @msg_host.match(HOSTNAME_EXTRACTION_REGEX)
+      unless m[:hostname].nil?
+        @msg_host = m[:hostname]
+      end
+    end
 
     event_title = ''
     alert_type = ''

manifests/init.pp

@@ -34,6 +34,11 @@
 #   $log_level
 #       Set value of 'log_level' variable. Default is 'info' as in dd-agent.
 #       Valid values here are: critical, debug, error, fatal, info, warn and warning.
+#   $hostname_extraction_regex
+#       Completely optional.
+#       Instead of reporting the puppet nodename, use this regex to extract the named
+#       'hostname' captured group to report the run in Datadog.
+#       ex.: '^(?<hostname>.*\.datadoghq\.com)(\.i-\w{8}\..*)?$'
 #   $log_to_syslog
 #       Set value of 'log_to_syslog' variable. Default is true -> yes as in dd-agent.
 #       Valid values here are: true or false.
@@ -103,6 +108,7 @@
   $log_to_syslog = true,
   $service_ensure = 'running',
   $service_enable = true,
+  $hostname_extraction_regex = nil,
   $use_mount = false,
   $dogstatsd_port = 8125,
   $statsd_forward_host = '',
@@ -203,6 +209,7 @@
     class { 'datadog_agent::reports':
       api_key           => $api_key,
       puppetmaster_user => $puppetmaster_user,
+      hostname_extraction_regex => $hostname_extraction_regex,
     }
   }
 

manifests/reports.pp

@@ -15,7 +15,8 @@
 #
 class datadog_agent::reports(
   $api_key,
-  $puppetmaster_user
+  $puppetmaster_user,
+  $hostname_extraction_regex
 ) {
 
   include datadog_agent::params

templates/datadog.yaml.erb

@@ -3,3 +3,6 @@
 #
 ---
 :datadog_api_key: '<%= @api_key %>'
+<% if @hostname_extraction_regex.nil? -%>
+:hostname_extraction_regex: '<%= @hostname_extraction_regex %>'
+<% end -%>