Manage option to use a custom lookup function (#80)

* Manage option to use a custom lookup function

Some people have written their own custom lookup function.
HDM needs to know if the function returns yaml or eyaml.

* switch from if ! to unless

* Parameter from optional to empty hash

* Update reference to new data type

REFERENCE.md

@@ -62,6 +62,7 @@ The following parameters are available in the `hdm` class:
 * [`ldap_settings`](#-hdm--ldap_settings)
 * [`ldap_bind_dn_password`](#-hdm--ldap_bind_dn_password)
 * [`hdm_hiera_config_file`](#-hdm--hdm_hiera_config_file)
+* [`custom_lookup_function`](#-hdm--custom_lookup_function)
 
 ##### <a name="-hdm--method"></a>`method`
 
@@ -321,6 +322,21 @@ want HDM to not use hiera.yaml.
 
 Default value: `'hiera.yaml'`
 
+##### <a name="-hdm--custom_lookup_function"></a>`custom_lookup_function`
+
+Data type: `Hash[String[1],Enum['yaml', 'eyaml']]`
+
+If you use your own developed hiera
+lookup function, HDM needs to know if the function returns yaml
+or eyaml data.
+Example:
+```
+  {
+    'functon_name' => '<yaml|eyaml>'
+  }
+
+Default value: `{}`
+
 ## Data types
 
 ### <a name="Hdm--Gitdata"></a>`Hdm::Gitdata`

manifests/init.pp

@@ -122,6 +122,15 @@
 # @param hdm_hiera_config_file Set to another file if you
 #   want HDM to not use hiera.yaml.
 #
+# @param custom_lookup_function If you use your own developed hiera
+#   lookup function, HDM needs to know if the function returns yaml
+#   or eyaml data.
+#   Example:
+#   ```
+#     {
+#       'functon_name' => '<yaml|eyaml>'
+#     }
+#
 # @example
 #   include hdm
 class hdm (
@@ -151,6 +160,7 @@
   Optional[Hdm::Gitdata]         $git_data               = undef,
   Optional[Hdm::Ldap_settings]   $ldap_settings          = undef,
   Optional[Sensitive[String[1]]] $ldap_bind_dn_password  = undef,
+  Hash[String[1],Enum['yaml', 'eyaml']]  $custom_lookup_function = {},
 ) {
   if $ldap_settings {
     if $ldap_bind_dn_password {

templates/hdm.yml.epp

@@ -15,3 +15,9 @@
     <%= $key %>: <%= $value %>
   <%- } -%>
 <%- } -%>
+<%- unless $hdm::custom_lookup_function.empty { -%>
+  custom_lookup_function_mapping:
+    <%- $hdm::custom_lookup_function.each |String $key, String $value| { -%>
+    <%= $key %>: <%= $value %>
+  <%- } -%>
+<%- } -%>