update nac_dc_validate to check if iac-validate is installed (#224)

plugins/action/common/nac_dc_validate.py

@@ -26,10 +26,17 @@
 
 from ansible.utils.display import Display
 from ansible.plugins.action import ActionBase
+from ansible.errors import AnsibleError
+
+try:
+    import iac_validate.validator
+    from iac_validate.yaml import load_yaml_files
+    from iac_validate.cli.options import DEFAULT_SCHEMA
+except ImportError as imp_exc:
+    IAC_VALIDATE_IMPORT_ERROR = imp_exc
+else:
+    IAC_VALIDATE_IMPORT_ERROR = None
 
-import iac_validate.validator
-from iac_validate.yaml import load_yaml_files
-from iac_validate.cli.options import DEFAULT_SCHEMA
 import os
 
 display = Display()
@@ -43,6 +50,9 @@ def run(self, tmp=None, task_vars=None):
         results['msg'] = None
         results['data'] = {}
 
+        if IAC_VALIDATE_IMPORT_ERROR:
+            raise AnsibleError('iac-validate not found and must be installed. Please pip install iac-validate.') from IAC_VALIDATE_IMPORT_ERROR
+
         schema = self._task.args.get('schema')
         rules = self._task.args.get('rules')
         mdata = self._task.args.get('mdata')