Merge pull request #462 from elyscape/fix/fqdn_rotate_seeds_with_argument

fqdn_rotate: Don't use the value itself as part of the random seed

Author: DavidS

README.markdown

@@ -259,7 +259,20 @@ fqdn_rand_string(10, '', 'custom seed')
 
 #### `fqdn_rotate`
 
-Rotates an array a random number of times, based on a node's fqdn. *Type*: rvalue.
+Rotates an array or string a random number of times, combining the `$fqdn` fact and an optional seed for repeatable randomness.
+
+*Usage:*
+~~~
+fqdn_rotate(VALUE, [SEED])
+~~~
+*Examples:*
+~~~
+fqdn_rotate(['a', 'b', 'c', 'd'])
+fqdn_rotate('abcd')
+fqdn_rotate([1, 2, 3], 'custom seed')
+~~~
+
+*Type*: rvalue.
 
 #### `get_module_path`
 

lib/puppet/parser/functions/fqdn_rotate.rb

@@ -2,16 +2,23 @@
 # fqdn_rotate.rb
 #
 
-module Puppet::Parser::Functions
-  newfunction(:fqdn_rotate, :type => :rvalue, :doc => <<-EOS
-Rotates an array a random number of times based on a nodes fqdn.
-    EOS
-  ) do |arguments|
+Puppet::Parser::Functions.newfunction(
+  :fqdn_rotate,
+  :type => :rvalue,
+  :doc => "Usage: `fqdn_rotate(VALUE, [SEED])`. VALUE is required and
+  must be an array or a string. SEED is optional and may be any number
+  or string.
+
+  Rotates VALUE a random number of times, combining the `$fqdn` fact and
+  the value of SEED for repeatable randomness. (That is, each node will
+  get a different random rotation from this function, but a given node's
+  result will be the same every time unless its hostname changes.) Adding
+  a SEED can be useful if you need more than one unrelated rotation.") do |args|
 
     raise(Puppet::ParseError, "fqdn_rotate(): Wrong number of arguments " +
-      "given (#{arguments.size} for 1)") if arguments.size < 1
+      "given (#{args.size} for 1)") if args.size < 1
 
-    value = arguments[0]
+    value = args.shift
     require 'digest/md5'
 
     unless value.is_a?(Array) || value.is_a?(String)
@@ -31,7 +38,7 @@ module Puppet::Parser::Functions
 
     elements = result.size
 
-    seed = Digest::MD5.hexdigest([lookupvar('::fqdn'),arguments].join(':')).hex
+    seed = Digest::MD5.hexdigest([lookupvar('::fqdn'),args].join(':')).hex
     # deterministic_rand() was added in Puppet 3.2.0; reimplement if necessary
     if Puppet::Util.respond_to?(:deterministic_rand)
       offset = Puppet::Util.deterministic_rand(seed, elements).to_i
@@ -51,7 +58,6 @@ module Puppet::Parser::Functions
     result = string ? result.join : result
 
     return result
-  end
 end
 
 # vim: set ts=2 sw=2 et :

spec/acceptance/fqdn_rotate_spec.rb

@@ -36,7 +36,7 @@
       EOS
 
       apply_manifest(pp, :catch_failures => true) do |r|
-        expect(r.stdout).to match(/fqdn_rotate is \["c", "d", "a", "b"\]/)
+        expect(r.stdout).to match(/fqdn_rotate is \["d", "a", "b", "c"\]/)
       end
     end
   end

spec/functions/fqdn_rotate_spec.rb

@@ -5,10 +5,6 @@
   it { is_expected.to run.with_params().and_raise_error(Puppet::ParseError, /wrong number of arguments/i) }
   it { is_expected.to run.with_params(0).and_raise_error(Puppet::ParseError, /Requires either array or string to work with/) }
   it { is_expected.to run.with_params({}).and_raise_error(Puppet::ParseError, /Requires either array or string to work with/) }
-  it {
-    pending("Current implementation ignores parameters after the first.")
-    is_expected.to run.with_params("one", "two").and_raise_error(Puppet::ParseError)
-  }
   it { is_expected.to run.with_params('').and_return('') }
   it { is_expected.to run.with_params('a').and_return('a') }
 
@@ -25,6 +21,18 @@
     expect(val1).to eq(val2)
   end
 
+  it "allows extra arguments to control the random rotation on a single host" do
+    val1 = fqdn_rotate("abcdefg", :extra_identifier => [1, "different", "host"])
+    val2 = fqdn_rotate("abcdefg", :extra_identifier => [2, "different", "host"])
+    expect(val1).not_to eq(val2)
+  end
+
+  it "considers the same host and same extra arguments to have the same random rotation" do
+    val1 = fqdn_rotate("abcdefg", :extra_identifier => [1, "same", "host"])
+    val2 = fqdn_rotate("abcdefg", :extra_identifier => [1, "same", "host"])
+    expect(val1).to eq(val2)
+  end
+
   it "should rotate a string to give different values on different hosts" do
     val1 = fqdn_rotate("abcdefg", :host => 'one')
     val2 = fqdn_rotate("abcdefg", :host => 'two')
@@ -38,7 +46,7 @@
 
   it "should use the Puppet::Util.deterministic_rand function" do
     if Puppet::Util.respond_to?(:deterministic_rand)
-      Puppet::Util.expects(:deterministic_rand).with(113646079810780526294648115052177588845,4)
+      Puppet::Util.expects(:deterministic_rand).with(44489829212339698569024999901561968770,4)
       fqdn_rotate("asdf")
     else
       skip 'Puppet::Util#deterministic_rand not available'
@@ -55,11 +63,13 @@
 
   def fqdn_rotate(value, args = {})
     host = args[:host] || '127.0.0.1'
+    extra = args[:extra_identifier] || []
 
     # workaround not being able to use let(:facts) because some tests need
     # multiple different hostnames in one context
     scope.stubs(:lookupvar).with("::fqdn").returns(host)
 
-    scope.function_fqdn_rotate([value])
+    function_args = [value] + extra
+    scope.function_fqdn_rotate(function_args)
   end
 end