diff --git a/doc/requirements.txt b/doc/requirements.txt
index c83b45b1..c4535d5d 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -3,12 +3,27 @@ openstackdocstheme>=2.2.1 # Apache-2.0
 reno>=3.1.0 # Apache-2.0
 
 # Install dependencies for tooz so that autodoc works.
-python-consul>=0.4.7 # MIT License
-sysv-ipc>=0.6.8 # BSD License
+## consul
+python-consul2>=0.0.16 # MIT License
+## etcd
+requests>=2.10.0 # Apache-2.0
+## etcd3
+etcd3>=0.12.0 # Apache-2.0
+grpcio>=1.18.0
+protobuf<4.0 # BSD License (3 clause)
+## etcd3gw
+etcd3gw!=0.2.6,>=0.1.0 # Apache-2.0
+## zake
 zake>=0.1.6 # Apache-2.0
-redis>=2.10.0 # MIT
+## redis
+redis>=3.1.0 # MIT
+## postgresql
 psycopg2>=2.5 # LGPL/ZPL
+## mysql
 PyMySQL>=0.6.2 # MIT License
+## zookeeper
+kazoo>=2.2 # Apache-2.0
+## memcached
 pymemcache!=1.3.0,>=1.2.9 # Apache 2.0 License
-etcd3>=0.6.2 # Apache-2.0
-etcd3gw>=0.1.0 # Apache-2.0
+## ipc
+sysv-ipc>=0.6.8 # BSD License
diff --git a/setup.cfg b/setup.cfg
index 87218160..c60f1483 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -51,6 +51,7 @@ etcd =
 etcd3 =
   etcd3>=0.12.0 # Apache-2.0
   grpcio>=1.18.0
+  protobuf<4.0 # BSD License (3 clause)
 etcd3gw =
   etcd3gw!=0.2.6,>=0.1.0 # Apache-2.0
 zake =