#puppethack allow undef value for bind-address

If set `bind-address` to `undef` the bind-address will not be set in the mysql-config file so MySQL is listening on all interfaces.

```puppet
class { '::mysql::server':
  override_options => {
    mysqld => {
      bind-address => undef,
    },
}
```

Author: Jethro van Ginkel

spec/classes/mysql_server_spec.rb

@@ -97,6 +97,21 @@
 
           it { is_expected.to contain_file('/tmp/error.log') }
         end
+        context 'default bind-address' do
+          let(:params) {  }
+
+          it { is_expected.to contain_file('mysql-config-file').with_content(/^bind-address = 127.0.0.1/) }
+        end
+        context 'with defined bind-address' do
+          let(:params) { { override_options: { 'mysqld' => { 'bind-address' => '1.1.1.1' } } } }
+
+          it { is_expected.to contain_file('mysql-config-file').with_content(/^bind-address = 1.1.1.1/) }
+        end
+        context 'without bind-address' do
+          let(:params) { { override_options: { 'mysqld' => { 'bind-address' => :undef } } } }
+
+          it { is_expected.to contain_file('mysql-config-file').without_content(/^bind-address/) }
+        end
       end
 
       context 'mysql::server::root_password' do

templates/my.cnf.erb

@@ -6,6 +6,8 @@
 <%     v.sort.map do |ki, vi| -%>
 <%       if ki == 'ssl-disable' or (ki =~ /^ssl/ and v['ssl-disable'] == true) -%>
 <%         next %>
+<%       elsif ki == 'bind-address' and vi == :undef -%>
+<%         next %>
 <%       elsif vi == true or vi == '' -%>
 <%=        ki %>
 <%       elsif vi.is_a?(Array) -%>