diff --git a/HACKING.rst b/HACKING.rst
index 377c647..a74ff73 100644
--- a/HACKING.rst
+++ b/HACKING.rst
@@ -186,3 +186,9 @@
 
 - Scenario tests
 - API tests that have a wide focus
+
+Sample Configuration File
+-------------------------
+The sample config file is autogenerated using a script. If any changes are made
+to the config variables in tempest then the sample config file must be
+regenerated. This can be done running the script: tools/generate_sample.sh