Fixes issue #274 by using recursive hash merge.

lib/puppet/parser/functions/mysql_deepmerge.rb

@@ -0,0 +1,52 @@
+module Puppet::Parser::Functions
+  newfunction(:mysql_deepmerge, :type => :rvalue, :doc => <<-'ENDHEREDOC') do |args|
+    Recursively merges two or more hashes together and returns the resulting hash.
+
+    For example:
+
+        $hash1 = {'one' => 1, 'two' => 2, 'three' => { 'four' => 4 } }
+        $hash2 = {'two' => 'dos', 'three' => { 'five' => 5 } }
+        $merged_hash = mysql_deepmerge($hash1, $hash2)
+        # The resulting hash is equivalent to:
+        # $merged_hash = { 'one' => 1, 'two' => 'dos', 'three' => { 'four' => 4, 'five' => 5 } }
+
+    When there is a duplicate key that is a hash, they are recursively merged.
+    When there is a duplicate key that is not a hash, the key in the rightmost hash will "win."
+
+    ENDHEREDOC
+
+    if args.length < 2
+      raise Puppet::ParseError, ("mysql_deepmerge(): wrong number of arguments (#{args.length}; must be at least 2)")
+    end
+
+    result = Hash.new
+    args.each do |arg|
+      next if arg.is_a? String and arg.empty? # empty string is synonym for puppet's undef
+      # If the argument was not a hash, skip it.
+      unless arg.is_a?(Hash)
+        raise Puppet::ParseError, "mysql_deepmerge: unexpected argument type #{arg.class}, only expects hash arguments"
+      end
+
+      # Now we have to traverse our hash assigning our non-hash values
+      # to the matching keys in our result while following our hash values
+      # and repeating the process.
+      overlay( result, arg )
+    end
+    return( result )
+  end
+end
+
+def overlay( hash1, hash2 )
+    hash2.each do |key, value|
+        if( value.is_a?(Hash) )
+            if( ! hash1.has_key?( key ) or ! hash1[key].is_a?(Hash))
+                hash1[key] = value
+            else
+                overlay( hash1[key], value )
+            end
+        else
+            hash1[key] = value
+        end
+    end
+end
+

manifests/server.pp

@@ -37,7 +37,7 @@ class mysql::server (
   }
 
   # Create a merged together set of options.  Rightmost hashes win over left.
-  $options = merge($mysql::params::default_options, $override_options)
+  $options = mysql_deepmerge($mysql::params::default_options, $override_options)
 
   Class['mysql::server::root_password'] -> Mysql::Db <| |>
 

spec/classes/mysql_server_spec.rb

@@ -9,6 +9,16 @@ describe 'mysql::server' do
     it { should contain_class('mysql::server::root_password') }
   end
 
+  # make sure that overriding the mysqld settings keeps the defaults for everything else
+  context 'with overrides' do
+    let(:params) {{ :override_options => { 'mysqld' => { 'socket' => '/var/lib/mysql/mysql.sock' } } }}
+    it do
+      should contain_file('/etc/my.cnf').with({
+        :mode => '0644',
+      }).with_content(/basedir/)
+    end
+  end
+
   context 'with remove_default_accounts set' do
     let (:params) {{ :remove_default_accounts => true }}
     it { should contain_class('mysql::server::account_security') }

spec/unit/puppet/functions/mysql_deepmerge_spec.rb

@@ -0,0 +1,77 @@
+#! /usr/bin/env ruby -S rspec
+
+require 'spec_helper'
+
+describe Puppet::Parser::Functions.function(:mysql_deepmerge) do
+  let(:scope) { PuppetlabsSpec::PuppetInternals.scope }
+
+  describe 'when calling mysql_deepmerge from puppet' do
+    it "should not compile when no arguments are passed" do
+      pending("Fails on 2.6.x, see bug #15912") if Puppet.version =~ /^2\.6\./
+      Puppet[:code] = '$x = mysql_deepmerge()'
+      expect {
+        scope.compiler.compile
+      }.to raise_error(Puppet::ParseError, /wrong number of arguments/)
+    end
+
+    it "should not compile when 1 argument is passed" do
+      pending("Fails on 2.6.x, see bug #15912") if Puppet.version =~ /^2\.6\./
+      Puppet[:code] = "$my_hash={'one' => 1}\n$x = mysql_deepmerge($my_hash)"
+      expect {
+        scope.compiler.compile
+      }.to raise_error(Puppet::ParseError, /wrong number of arguments/)
+    end
+  end
+
+  describe 'when calling mysql_deepmerge on the scope instance' do
+    it 'should require all parameters are hashes' do
+      expect { new_hash = scope.function_mysql_deepmerge([{}, '2'])}.to raise_error(Puppet::ParseError, /unexpected argument type String/)
+      expect { new_hash = scope.function_mysql_deepmerge([{}, 2])}.to raise_error(Puppet::ParseError, /unexpected argument type Fixnum/)
+    end
+
+    it 'should accept empty strings as puppet undef' do
+      expect { new_hash = scope.function_mysql_deepmerge([{}, ''])}.not_to raise_error(Puppet::ParseError, /unexpected argument type String/)
+    end
+
+    it 'should be able to mysql_deepmerge two hashes' do
+      new_hash = scope.function_mysql_deepmerge([{'one' => '1', 'two' => '1'}, {'two' => '2', 'three' => '2'}])
+      new_hash['one'].should   == '1'
+      new_hash['two'].should   == '2'
+      new_hash['three'].should == '2'
+    end
+
+    it 'should mysql_deepmerge multiple hashes' do
+      hash = scope.function_mysql_deepmerge([{'one' => 1}, {'one' => '2'}, {'one' => '3'}])
+      hash['one'].should == '3'
+    end
+
+    it 'should accept empty hashes' do
+      scope.function_mysql_deepmerge([{},{},{}]).should == {}
+    end
+
+    it 'should mysql_deepmerge subhashes' do
+      hash = scope.function_mysql_deepmerge([{'one' => 1}, {'two' => 2, 'three' => { 'four' => 4 } }])
+      hash['one'].should == 1
+      hash['two'].should == 2
+      hash['three'].should == { 'four' => 4 }
+    end
+
+    it 'should append to subhashes' do
+      hash = scope.function_mysql_deepmerge([{'one' => { 'two' => 2 } }, { 'one' => { 'three' => 3 } }])
+      hash['one'].should == { 'two' => 2, 'three' => 3 }
+    end
+
+    it 'should append to subhashes 2' do
+      hash = scope.function_mysql_deepmerge([{'one' => 1, 'two' => 2, 'three' => { 'four' => 4 } }, {'two' => 'dos', 'three' => { 'five' => 5 } }])
+      hash['one'].should == 1
+      hash['two'].should == 'dos'
+      hash['three'].should == { 'four' => 4, 'five' => 5 }
+    end
+
+    it 'should append to subhashes 3' do
+      hash = scope.function_mysql_deepmerge([{ 'key1' => { 'a' => 1, 'b' => 2 }, 'key2' => { 'c' => 3 } }, { 'key1' => { 'b' => 99 } }])
+      hash['key1'].should == { 'a' => 1, 'b' => 99 }
+      hash['key2'].should == { 'c' => 3 }
+    end
+  end
+end