diff --git a/doc/configuration.rst b/doc/configuration.rst
index 6d97aa8..c8411dc 100644
--- a/doc/configuration.rst
+++ b/doc/configuration.rst
@@ -191,6 +191,21 @@ Defaults to: ``False`` for development, must be ``True`` in production with
 https.
 
 
+SESSION_TYPE
+~~~~~~~~~~~~
+
+Enables the `flask-session <https://pythonhosted.org/Flask-Session/>`_
+extension if set to a value other than ``None``. The ``flask-session``
+package needs to be installed and proper
+`configuration https://pythonhosted.org/Flask-Session/#configuration`_
+needs to be included in the Pagure config file.
+
+This is useful when the Pagure server needs to be scaled up to multiple
+instances, which requires the flask session keys to be shared between those.
+Flask-session allows you to use Redis, Memcached, relational database
+or MongoDB for storing shared session keys.
+
+
 FROM_EMAIL
 ~~~~~~~~~~
 
diff --git a/pagure/flask_app.py b/pagure/flask_app.py
index acbf2b8..75d558a 100644
--- a/pagure/flask_app.py
+++ b/pagure/flask_app.py
@@ -65,6 +65,10 @@ def create_app(config=None):
     if config:
         app.config.update(config)
 
+    if app.config.get('SESSION_TYPE', None) is not None:
+        import flask_session
+        flask_session.Session(app)
+
     logging.basicConfig()
     logging.config.dictConfig(app.config.get('LOGGING') or {'version': 1})
 
diff --git a/requirements.txt b/requirements.txt
index 2320795..2def484 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -36,6 +36,9 @@ wtforms
 # Required only for the `oidc` authentication backend
 # flask-oidc
 
+# Required only if `USE_FLASK_SESSION_EXT` is set to `True`
+# flask-session
+
 # Required only for the `fas` and `openid` authentication backends
 # python-fedora