From dffe6682e54f165c04063edd1650c169a22198cf Mon Sep 17 00:00:00 2001
From: "Isaac I.Y. Saito" <130s@2000.jukuin.keio.ac.jp>
Date: Fri, 22 Sep 2017 20:39:51 -0700
Subject: [PATCH] [doc] Clarify Docker image requirement.

---
 doc/index.rst | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/doc/index.rst b/doc/index.rst
index 37f9c580b..122951875 100644
--- a/doc/index.rst
+++ b/doc/index.rst
@@ -198,7 +198,12 @@ As you see in the `optional variables section <./index.rst#optional-environment-
 Pulling Docker image from an online hub
 +++++++++++++++++++++++++++++++++++++++
 
-You can use `DOCKER_IMAGE` variable for this.
+You can pull any `Docker` image by specifying in `DOCKER_IMAGE` variable, as long as the following requirement is met:
+
+* `python-catkin-tools`, `python-pip`, `python-rosdep`, `python-wstool`
+* sources.list set up (`example <http://wiki.ros.org/kinetic/Installation/Ubuntu#Installation.2BAC8-Ubuntu.2BAC8-Sources.Setup_your_sources.list>`_).
+
+If your Docker image is missing any of the above libraries, then you can still pass their name by `ADDITIONAL_DEBS` (see `variables section <./index.rst#optional-environment-variables>`_).
 
 Note-1. This disables the handling of `ROS_REPOSITORY_PATH` and `ROS_DISTRO` as ROS needs already to be installed in the image.