add ATMOSPHERE_ANSIBLE_VARS_PATH

The path for ansible group_vars and host_vars.
This to build a multinode development cluster with own configs, that are
not
generated by molecule. This way you can test your configs before you
bring them to production.
diff --git a/README.md b/README.md
index 0571711..d4c03ef 100644
--- a/README.md
+++ b/README.md
@@ -86,6 +86,11 @@
   with StepCA from SmallStep it is possible to run a internal ACME server.
   The CA of that ACME server should be present in the instance image.
 
+* `ATMOSPHERE_ANSIBLE_VARS_PATH`: The path for ansible group_vars and host_vars.
+  This to build a multinode development cluster with own configs, that are not
+  generated by molecule. This way you can test your configs before you bring
+  them to production.
+
 Once you're ready to get started, you can run the following command to install
 poetry dependencies:
 
diff --git a/molecule/default/molecule.yml b/molecule/default/molecule.yml
index ff820db..6696579 100644
--- a/molecule/default/molecule.yml
+++ b/molecule/default/molecule.yml
@@ -49,7 +49,7 @@
       pipelining: true
   inventory:
     links:
-      host_vars: "${MOLECULE_SCENARIO_DIRECTORY}/host_vars"
-      group_vars: "${MOLECULE_SCENARIO_DIRECTORY}/group_vars"
+      host_vars: "${ATMOSPHERE_ANSIBLE_VARS_PATH-$MOLECULE_SCENARIO_DIRECTORY}/host_vars"
+      group_vars: "${ATMOSPHERE_ANSIBLE_VARS_PATH-$MOLECULE_SCENARIO_DIRECTORY}/group_vars"
 verifier:
   name: ansible