Adding an example yaml node script

Signed-off-by: Luke Kanies <luke@madstop.com>

1 files changed, 99 insertions, 0 deletions

diff --git a/ext/yaml_nodes.rb b/ext/yaml_nodes.rb
new file mode 100755
index 000000000..4715b16de
--- /dev/null
+++ b/ext/yaml_nodes.rb
@@ -0,0 +1,99 @@
+#!/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.
+#
+# = Author
+#
+# Luke Kanies
+#
+# = Copyright
+#
+# Copyright (c) 2009 Reductive Labs, Inc.
+# Licensed under the GPL2
+
+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 %s" % 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 %s" % 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)