added validation for needed variables

environments/aws/aws_create.yml

diff --git a/environments/aws/aws_create.yml b/environments/aws/aws_create.yml
index 778e697..357db31 100644
--- a/environments/aws/aws_create.yml
+++ b/environments/aws/aws_create.yml
@@ -10,6 +10,36 @@
 
   - ec2_facts:
 
+  - name: Validate that provision_profile is provided
+    fail:
+      msg: Please indicate the provision_profile to use from those available in the profiles folder
+    when: provision_profile is not defined
+
+  - name: Validate that os_selection is provided
+    fail:
+      msg: Please indicate the os_selection to use from those available in the os folder
+    when: os_selection is not defined
+
+  - name: Validate that security_group is provided
+    fail:
+      msg: Please indicate the security_group to use from those available in the security folder
+    when: security_group is not defined
+
+  - name: Validate that start is provided
+    fail:
+      msg: Please indicate the starting node
+    when: start is not defined
+
+  - name: Validate that end is provided
+    fail:
+      msg: Please indicate the starting node
+    when: end is not defined
+
+  - name: Validate that security_group is provided
+    fail:
+      msg: Please indicate the security_group to use from those available in the security folder
+    when: security_group is not defined
+
   - name: "Load provision profile settings"
     include_vars: "profiles/{{ provision_profile }}.yml"