Update docker config docs for insecure registry

Change-Id: I751c3901b831aaed03b88d36184cd9cc5df1789b
Closes-Bug: #1779110

doc/source/user/multinode.rst

@@ -70,86 +70,26 @@ Configure Docker on all nodes
 
 After starting the registry, it is necessary to instruct Docker that
 it will be communicating with an insecure registry.
-For example, To enable insecure registry communication on CentOS,
-modify the ``/etc/sysconfig/docker`` file to contain the following where
+For example, To enable insecure registry communication,
+modify the ``/etc/docker/daemon.json`` file to contain the following where
 ``192.168.1.100`` is the IP address of the machine where the registry
 is currently running:
 
-.. path /etc/sysconfig/docker
-.. code-block:: ini
-
-   INSECURE_REGISTRY="--insecure-registry 192.168.1.100:5000"
-
-.. end
-
-For Ubuntu, check whether its using upstart or systemd.
-
-.. code-block:: console
-
-   # stat /proc/1/exe
-   File: '/proc/1/exe' -> '/lib/systemd/systemd'
-
-Edit ``/etc/default/docker`` and add the following configuration:
-
-.. path /etc/default/docker
-.. code-block:: ini
-
-   DOCKER_OPTS="--insecure-registry 192.168.1.100:5000"
-
-.. end
-
-If Ubuntu is using systemd, additional settings needs to be configured.
-Copy Docker's systemd unit file to ``/etc/systemd/system/`` directory:
-
-.. code-block:: console
+.. path /etc/docker/daemon.json
+.. code-block:: json
 
-   cp /lib/systemd/system/docker.service /etc/systemd/system/docker.service
+   {
+     "insecure-registries" : ["192.168.1.100:5000"]
+   }
 
 .. end
 
-Next, modify ``/etc/systemd/system/docker.service``, add ``environmentFile``
-variable and add ``$DOCKER_OPTS`` to the end of ExecStart in ``[Service]``
-section.
-
-For CentOS:
-
-.. path /etc/systemd/system/docker.service
-.. code-block:: ini
-
-    [Service]
-    MountFlags=shared
-    EnvironmentFile=/etc/sysconfig/docker
-    ExecStart=
-    ExecStart=/usr/bin/docker daemon $INSECURE_REGISTRY
-
-.. end
-
-For Ubuntu:
-
-.. path /etc/systemd/system/docker.service
-.. code-block:: ini
-
-   [Service]
-   MountFlags=shared
-   EnvironmentFile=-/etc/default/docker
-   ExecStart=
-   ExecStart=/usr/bin/docker daemon -H fd:// $DOCKER_OPTS
-
-.. end
-
-.. note::
-
-   If your docker version is >=1.13.0, the ``docker daemon`` should be replaced
-   with ``dockerd``.
-
-
 Restart Docker by executing the following commands:
 
 For CentOS or Ubuntu with systemd:
 
 .. code-block:: console
 
-   systemctl daemon-reload
    systemctl restart docker
 
 .. end