Add error message on ldap lookup

lookup_plugins/ldap.py

@@ -1,10 +1,18 @@
+"""
+To use this lookup plugin, you need to pass ldap:
+ssh -L 1636:172.16.10.1:636 172.16.10.1
+"""
+
 import ipaddress
 
 from ansible.errors import AnsibleError, AnsibleParserError
 from ansible.plugins.lookup import LookupBase
 from ansible.utils.display import Display
 
-import ldap
+try:
+    import ldap
+except ImportError:
+    raise AnsibleError("You need to install python3-ldap")
 
 display = Display()