Puppet Function: extlib::cache_data

Defined in:
lib/puppet/functions/extlib/cache_data.rb
Function type:
Ruby 4.x API

Summary

Retrieves data from a cache file, or creates it with supplied data if the file doesn't exist

Overview

extlib::cache_data(String[1] $namespace, String[1] $name, Any $initial_data) ⇒ Any

Retrieves data from a cache file, or creates it with supplied data if the file doesn’t exist

Useful for having data that’s randomly generated once on the master side (e.g. a password), but then stays the same on subsequent runs. Because it’s stored on the master on disk, it doesn’t work when you use mulitple Puppet masters that don’t share their vardir.

Examples:

Calling the function

$password = cache_data('mysql', 'mysql_password', 'this_is_my_password')

With a random password

$password = cache_data('mysql', 'mysql_password', random_password())

Parameters:

  • namespace (String[1]) —

    Namespace for the cache

  • name (String[1]) —

    Cache key within the namespace

  • initial_data (Any) —

    The data for when there is no cache yet

Returns:

  • (Any) —

    The cached value when it exists. The initial data when no cache exists



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# File 'lib/puppet/functions/extlib/cache_data.rb', line 22

Puppet::Functions.create_function(:'extlib::cache_data') do
  # @param namespace Namespace for the cache
  # @param name Cache key within the namespace
  # @param initial_data The data for when there is no cache yet
  # @return The cached value when it exists. The initial data when no cache exists
  dispatch :cache_data do
    param 'String[1]', :namespace
    param 'String[1]', :name
    param 'Any', :initial_data
    return_type 'Any'
  end

  def cache_data(namespace, name, initial_data)
    cache_dir = File.join(Puppet[:vardir], namespace)
    cache = File.join(cache_dir, name)

    if File.exist? cache
      YAML.safe_load(File.read(cache))
    else
      FileUtils.mkdir_p(cache_dir)
      File.open(cache, 'w', 0o600) do |c|
        c.write(YAML.dump(initial_data))
      end
      File.chown(File.stat(Puppet[:vardir]).uid, nil, cache)
      File.chown(File.stat(Puppet[:vardir]).uid, nil, cache_dir)
      initial_data
    end
  end
end