From 740ca7dc8053be93e43392ca61b2f308c0596d19 Mon Sep 17 00:00:00 2001
From: Reid Vandewiele <reid@puppetlabs.com>
Date: Fri, 7 Apr 2017 15:13:59 -0700
Subject: (FACT-932) Add new function, fact()
The fact() function allows dot-notation reference to facts. It is an
alternative to using $facts directly with array-indexing. Array-indexing
is often onerous to use since it doesn't align with how structured facts
are accessed elsewhere in the ecosystem and if any element in a
multi-step path doesn't exist, array indexing can cause a compilation
failure.
Example usage:
fact('os.family')
---
lib/puppet/functions/fact.rb | 58 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 58 insertions(+)
create mode 100644 lib/puppet/functions/fact.rb
(limited to 'lib')
diff --git a/lib/puppet/functions/fact.rb b/lib/puppet/functions/fact.rb
new file mode 100644
index 0000000..dfb048b
--- /dev/null
+++ b/lib/puppet/functions/fact.rb
@@ -0,0 +1,58 @@
+# Digs into the facts hash using dot-notation
+#
+# Example usage:
+#
+# fact('osfamily')
+# fact('os.architecture')
+#
+# Array indexing:
+#
+# fact('mountpoints."/dev".options.1')
+#
+# Fact containing a "." in the name:
+#
+# fact('vmware."VRA.version"')
+#
+Puppet::Functions.create_function(:fact) do
+ dispatch :fact do
+ param 'String', :fact_name
+ end
+
+ def to_dot_syntax(array_path)
+ array_path.map do |string|
+ string.include?('.') ? %Q{"#{string}"} : string
+ end.join('.')
+ end
+
+ def fact(fact_name)
+ facts = closure_scope['facts']
+
+ # Transform the dot-notation string into an array of paths to walk. Make
+ # sure to correctly extract double-quoted values containing dots as single
+ # elements in the path.
+ path = fact_name.scan(/([^."]+)|(?:")([^"]+)(?:")/).map {|x| x.compact.first }
+
+ walked_path = []
+ path.reduce(facts) do |d, k|
+ return nil if d.nil? || k.nil?
+
+ case
+ when d.is_a?(Array)
+ begin
+ result = d[Integer(k)]
+ rescue ArgumentError => e
+ Puppet.warning("fact request for #{fact_name} returning nil: '#{to_dot_syntax(walked_path)}' is an array; cannot index to '#{k}'")
+ result = nil
+ end
+ when d.is_a?(Hash)
+ result = d[k]
+ else
+ Puppet.warning("fact request for #{fact_name} returning nil: '#{to_dot_syntax(walked_path)}' is not a collection; cannot walk to '#{k}'")
+ result = nil
+ end
+
+ walked_path << k
+ result
+ end
+ end
+end
--
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