Issue 122 - Puppet ENC via Hiera

hiera/puppet-node-classifier.rb

Index: hiera/puppet-node-classifier.rb
===================================================================
new file mode 100755
--- /dev/null
+++ b/hiera/puppet-node-classifier.rb
@@ -0,0 +1,93 @@
+#!/usr/bin/env ruby
+# This script is a node classifier for Puppet that operates on top of Hiera
+# and uses a custom hosts.yaml config to map host roles.
+
+require 'getoptlong'
+require 'hiera'
+require 'socket'
+require 'yaml'
+
+# Where to search for the Hiera configuration
+HIERA_CONFIG = ENV.fetch('PUPPET_HIERA_CONFIG', '/etc/puppet/hiera.yaml')
+# Where to search for the Hosts configuration
+HOSTS_CONFIG = ENV.fetch('PUPPET_HOSTS_CONFIG', '/etc/puppet/infrastructure/hiera/environment/hosts.yaml')

[Wladimir Palant, 2014/11/17 16:43:36]

I don't think hardcoding /etc/puppet/infrastructure/hiera here is necessary,
File.dirname(__FILE__) should do?

[mathias, 2014/11/27 00:30:18]

It would work in this case, indeed. Yet I don't believe it's a good idea to
operate with paths relative to some script, especially if the desired files are
not siblings in the very same folder (but e.g. in sub-directories, as in this
case). The POSIX way of assuming some default location in /etc seems to be more
"clean", and one could consider the /etc/puppet/infrastructure path as the
canonical configuration path within our flavor of Puppet - especially since
we're using the absolute path's in related resources as well (kick.py and
install-precise.py, for example).

+
+# The current script name, used for logging and usage hints
+BASENAME = File.basename($0)
+
+# Although there's no need for any options in particular yet, the script
+# still recognizes a --help option, which is considered the bare minimum by
+# convention. Nonetheless, future options may become integrated here (see
+# also http://ruby-doc.org/stdlib/libdoc/getoptlong/rdoc/GetoptLong.html):
+GetoptLong.new(
+  ['--help', '-h', GetoptLong::NO_ARGUMENT]
+).each do |opt, arg|
+  case opt
+
+    when '--help'
+      puts <<-END
+Usage:  #{BASENAME} [hostname]
+        #{BASENAME} example.com
+        #{BASENAME} --help
+
+Options:
+
+    --help, -h
+        Display this help message and exit gracefully.
+
+Environment:
+
+    PUPPET_HIERA_CONFIG=#{HIERA_CONFIG}
+        Where to find the hiera configuration file.
+    PUPPET_HOSTS_CONFIG=#{HOSTS_CONFIG}
+        Where to find the hosts configuration file.
+
+END
+      exit 0
+
+  end
+end
+
+# Only one additional non-option argument is allowed, in order to explicitly
+# specify a hostname to use instead of the default:
+case ARGV.length
+  when 0
+    hostname = Socket.gethostname
+  when 1
+    hostname = ARGV[0][/^[^.]+/]
+  else
+    STDERR.puts <<-END
+#{BASENAME}: unknown option: #{ARGV[0]}
+#{BASENAME}: try #{BASENAME} --help
+END
+    exit 1
+end
+
+# Extract the server -> hostname -> role information from the hosts
+# configuration file:
+begin
+  config = YAML.load_file(HOSTS_CONFIG)
+  servers = config.fetch("servers", {})
+  host = servers.fetch(hostname, {})
+  role = host.fetch("role", "default")
+rescue Exception => error
+  STDERR.puts "#{BASENAME}: #{error.message}: #{HOSTS_CONFIG}"
+  exit 1
+end
+
+# Map Hiera data into the structure Puppet expects an ENC to generate (see
+# https://docs.puppetlabs.com/guides/external_nodes.html for more info):
+begin
+  hiera = Hiera.new(:config => HIERA_CONFIG)
+  scope = {'::hostname'=> hostname, '::role'=> role}
+  result = {
+     'classes'=> hiera.lookup('classes', {}, scope, nil, :hash),
+     'parameters'=> hiera.lookup('parameters', {}, scope, nil, :hash),
+  }
+rescue Exception => error
+  STDERR.puts "#{BASENAME}: #{error.message}: #{HIERA_CONFIG}"
+  exit 1
+end
+
+puts result.to_yaml
+