Add Configuring Docker article [WIP]

Fixes #12088

Signed-off-by: Ankush Agarwal <ankushagarwal11@gmail.com>

docs/mkdocs.yml

@@ -109,6 +109,7 @@ pages:
 - ['articles/dockerfile_best-practices.md', 'Articles', 'Best practices for writing Dockerfiles']
 - ['articles/certificates.md', 'Articles', 'Using certificates for repository client verification']
 - ['articles/using_supervisord.md', 'Articles', 'Using Supervisor']
+- ['articles/configuring.md', 'Articles', 'Configuring Docker']
 - ['articles/cfengine_process_management.md', 'Articles', 'Process management with CFEngine']
 - ['articles/puppet.md', 'Articles', 'Using Puppet']
 - ['articles/chef.md', 'Articles', 'Using Chef']

docs/sources/articles/configuring.md

@@ -0,0 +1,60 @@
+page_title: Configuring Docker
+page_description: Configuring the Docker daemon on various distributions
+page_keywords: docker, daemon, configuration
+
+# Configuring Docker on various distributions
+
+After successfully installing the Docker daemon on a distribution, it runs with it's default
+config. Usually it is required to change the default config to meet one's personal requirements.
+ 
+Docker can be configured by passing the config flags to the daemon directly if the daemon
+is started directly. Usually that is not the case. A process manager (like SysVinit, Upstart,
+systemd, etc) is responsible for starting and running the daemon.
+
+Some common config options are
+
+* `-D` : Enable debug mode
+
+* `-H` : Daemon socket(s) to connect to   
+
+* `--tls` : Enable or disable TLS authentication
+
+The complete list of flags can found at [Docker Command Line Reference](/reference/commandline/cli/)
+
+## Ubuntu
+
+After successfully [installing Docker for Ubuntu](/installation/ubuntulinux/), you can check the
+running status using (if running Upstart)
+
+    $ sudo status docker
+    docker start/running, process 989
+
+You can start/stop/restart `docker` using
+
+    $ sudo start docker
+
+    $ sudo stop docker
+
+    $ sudo restart docker
+
+
+### Configuring Docker
+
+Docker options can be configured by editing the file `/etc/default/docker`. If this file does not 
+exist, it needs to be createdThis file contains a variable named `DOCKER_OPTS`. All the 
+config options need to be placed in this variable. For example
+
+    DOCKER_OPTS=" --dns 8.8.8.8 -D --tls=false -H tcp://0.0.0.0:2375 "
+
+The above daemon options : 
+
+1. Set dns server for all containers
+
+2. Enable Debug mode 
+
+3. Set tls to false
+
+4. Make the daemon listen for connections on `tcp://0.0.0.0:2375`
+
+After saving the file, restart docker using `sudo restart docker`. Verify that the daemon is
+running with the options specified by running `ps aux | grep docker | grep -v grep`