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|
#!/usr/bin/ruby
#
# = Synopsis
#
# Use YAML files to provide external node support.
#
# = Usage
#
# yaml-nodes <host>
#
# = Description
#
# This is a simple example external node script. It allows you to maintain your
# node information in yaml files, and it will find a given node's file and produce
# it on stdout. It has simple inheritance, in that a node can specify a parent
# node, and the node will inherit that parent's classes and parameters.
#
# = Options
#
# help::
# Print this help message
#
# yamldir::
# Specify where the yaml is found. Defaults to 'yaml' in the current directory.
#
# = License
# Copyright 2011 Luke Kanies
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
require 'yaml'
require 'optparse'
BASEDIR = Dir.chdir(File.dirname(__FILE__) + "/..") { Dir.getwd }
options = {:yamldir => File.join(BASEDIR, "yaml")}
OptionParser.new do |opts|
opts.banner = "Usage: yaml-nodes [options] <host>"
opts.on("-y dir", "--yamldir dir", "Specify the directory with the YAML files") do |arg|
raise "YAML directory #{arg} does not exist or is not a directory" unless FileTest.directory?(arg)
options[:yamldir] = arg
end
opts.on("-h", "--help", "Print this help") do
puts opts.help
exit(0)
end
end.parse!
# Read in a pure yaml representation of our node.
def read_node(node)
nodefile = File.join(YAMLDIR, "#{node}.yaml")
if FileTest.exist?(nodefile)
return YAML.load_file(nodefile)
else
raise "Could not find information for #{node}"
end
end
node = ARGV[0]
info = read_node(node)
# Iterate over any provided parents, merging in there information.
parents_seen = []
while parent = info["parent"]
raise "Found inheritance loop with parent #{parent}" if parents_seen.include?(parent)
parents_seen << parent
info.delete("parent")
parent_info = read_node(parent)
# Include any parent classes in our list.
if pclasses = parent_info["classes"]
info["classes"] += pclasses
info["classes"].uniq!
end
# And inherit parameters from our parent, while preferring our own values.
if pparams = parent_info["parameters"]
# When using Hash#merge, the hash being merged in wins, and we
# want the subnode parameters to be the parent node parameters.
info["parameters"] = pparams.merge(info["parameters"])
end
# Copy over any parent node name.
if pparent = parent_info["parent"]
info["parent"] = pparent
end
end
puts YAML.dump(info)
|
