diff --git a/roles/ensure-twine/README.rst b/roles/ensure-twine/README.rst
index 64e4f5172..604d61a54 100644
--- a/roles/ensure-twine/README.rst
+++ b/roles/ensure-twine/README.rst
@@ -7,3 +7,17 @@ Ensure twine is installed.
 
    The python interpreter to use to install twine if it is not already
    installed. Set it to "python3" to use python 3, for example.
+
+**Output Variables**
+
+.. zuul:rolevar:: twine_excutable
+   :default: twine
+
+   After running this role, ``twine_executable`` will be set as the path
+   to a valid ``twine``.
+
+   At role runtime, look for an existing ``twine`` at this specific
+   path.  Note the default (``twine``) effectively means to find tox in
+   the current ``$PATH``.  For example, if your base image
+   pre-installs twine in an out-of-path environment, set this so the
+   role does not attempt to install the user version.