Add support for another approach to load group_vars (#42)

* Add support for another approach to load group_vars from external repository and not from group_vars.

* change merge_dict_vars to cluster_vars_format. add Readme to action plugins

* add default to cluster_vars_format|default('native')

Co-authored-by: Taras Nychko <[email protected]>

_dependencies/action_plugins/README_merge_vars.md

@@ -0,0 +1,33 @@
+### Action Plugin Merge_Vars
+
+this plugin similar to `include_vars`, but designed to merge all the variables(including dicts) in the files specified by from rather than replacing(default ansible behaviour for dicts).
+
+This plugin is designed to support the inclusion of DRY application configuration within ansible vars. For example, if you have multiple porjects (foo, bar), and multiple environments (dev, qa, prod), and some vars are shared at various levels (project, or environment), and you want to keep your configuration DRY.
+
+Example:
+
+  ```
+  environment/
+  └── aws
+      ├── cbe
+      │   └── clusterid
+      │       ├── app_vars.yml
+      │       ├── cluster.yml
+      │       └── dev_metadata.yml
+      └── dev.yml
+    ```
+
+#### How to use:
+
+```
+  - name: Merge dict
+    merge_vars:
+        ignore_missing_files: True
+        from:
+        	- "test1.yml"
+        	- "test2.yml"
+```
+
+where, 
+	ignore_missing_files if false - raise an error, default behaviour
+	from - list of files to be merged - order matters.

_dependencies/action_plugins/merge_vars.py

@@ -0,0 +1,78 @@
+from __future__ import (absolute_import, division, print_function)
+__metaclass__ = type
+
+from ansible.errors import AnsibleError
+from ansible.plugins.action import ActionBase
+from ansible.utils.vars import merge_hash
+from ansible.module_utils._text import to_native, to_text
+from os import path, listdir
+
+class ActionModule(ActionBase):
+
+    VALID_ARGUMENTS = [ 'from', 'ignore_missing_files' ]
+
+    def run(self, tmp=None, task_vars=None):
+
+        if task_vars is None:
+            task_vars = dict()
+
+        for arg in self._task.args:
+            if not arg in self.VALID_ARGUMENTS:
+                raise AnsibleError('%s is not a valid option in merge_vars' % arg)
+
+        self.ignore_missing_files = self._task.args.get('ignore_missing_files', False)
+
+        self.show_content = True;
+        self._task.action = 'include_vars';
+
+        failed = False
+
+        files = []
+        for source in self._task.args['from']:
+            if path.isfile(source):
+                files.append(source)
+            elif not path.isfile(source) and self.ignore_missing_files:
+                continue
+            elif path.isdir(source):
+                dirfiles = [path.join(source, filename) for filename in listdir(source)]
+                dirfiles.sort()
+                files.append(dirfiles)
+            elif not path.isdir(source) and self.ignore_missing_files:
+                continue
+            else:
+                failed = True
+                err_msg = to_native('%s does not exist' % source)
+                break
+
+        data = {}
+        if not failed:
+            for filename in files:
+                try:
+                    data = merge_hash(data, self._load_from_file(filename))
+
+                except AnsibleError as e:
+                    failed = True
+                    err_msg = to_native(e)
+
+        result = super(ActionModule, self).run(task_vars=task_vars)
+
+        if failed:
+            result['failed'] = failed
+            result['message'] = err_msg
+
+        result['ansible_included_var_files'] = files
+        result['ansible_facts'] = data
+        result['_ansible_no_log'] = not self.show_content
+
+        return result
+
+    def _load_from_file(self, filename):
+        # this is the approach used by include_vars in order to get the show_content
+        # value based on whether decryption occured.  load_from_file does not return
+        # that value. 
+        #    https://github.com/ansible/ansible/blob/v2.7.5/lib/ansible/plugins/action/include_vars.py#L236-L240
+        b_data, show_content = self._loader._get_file_contents(filename)
+        data = to_text(b_data, errors='surrogate_or_strict')
+
+        self.show_content = show_content
+        return self._loader.load(data, file_name=filename, show_content=show_content) or {}

_dependencies/tasks/main.yml

@@ -1,7 +1,19 @@
 ---
 
-- name: Force include of group_vars on localhost (no inventory yet, so cannot import automatically)
-  include_vars: { dir: "{{ playbook_dir }}/group_vars/{{ clusterid }}" }
+- block:
+  - name: Force include of group_vars on localhost (no inventory yet, so cannot import automatically)
+    include_vars: { dir: "{{ playbook_dir }}/group_vars/{{ clusterid }}" }
+    when: 
+      - cluster_vars_format|default('native') == 'native'
+
+  - name: Merge dict from different configuration files
+    merge_vars:
+        ignore_missing_files: True
+        from: "{{ merge_dict_vars_list }}"
+    when:
+      - cluster_vars_format|default('native') == 'tiered'
+      - merge_dict_vars_list is defined and merge_dict_vars_list | length > 0
+
   tags: clusterverse_clean,clusterverse_create,clusterverse_dynamic_inventory,clusterverse_config,clusterverse_readiness
 
 - name: Preflight check