diff --git a/doc/source/conf.py b/doc/source/conf.py
index daa293c..3ec25ea 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -13,6 +13,19 @@
 
 import sys
 import os
+import subprocess
+
+# Build a tempest sample config file:
+def build_sample_config(app):
+    root_dir = os.path.dirname(
+        os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+    subprocess.call(["oslo-config-generator", "--config-file",
+                     "tools/config/config-generator.tempest.conf",
+                     "--output-file", "doc/source/_static/tempest.conf"],
+                    cwd=root_dir)
+
+def setup(app):
+    app.connect('builder-inited', build_sample_config)
 
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
diff --git a/tox.ini b/tox.ini
index eae6fc7..15652e8 100644
--- a/tox.ini
+++ b/tox.ini
@@ -110,7 +110,6 @@
 [testenv:docs]
 # The sample config file we generate is included in the sphinxdoc, so build that first.
 commands =
-   oslo-config-generator --config-file tools/config/config-generator.tempest.conf --output-file doc/source/_static/tempest.conf
    python setup.py build_sphinx {posargs}
 
 [testenv:pep8]