Adding gluster-object to gluster docker hub. Current changes are for CentOS.

Refer docker-gluster-swift/README.md for setting up gluster-object Docker container.

Signed-off-by: Saravanakumar Arumugam <sarumuga@redhat.com>

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+
+# docker-gluster-swift
+docker-gluster-swift is to provide object interface for a Gluster volume.
+
+Let us see how to run gluster-swift inside a docker container.
+
+## Building
+
+```bash
+# docker build --rm --tag gluster-swift .
+```
+
+## Running
+
+On the host machine, mount one or more gluster volumes under the directory
+`/mnt/gluster-object` with mountpoint name being same as that of the volume.
+
+For example, if you have two gluster volumes named `test` and `test2`, they
+should be mounted at `/mnt/gluster-object/test` and `/mnt/gluster-object/test2`
+respectively. This directory on the host machine containing all the individual
+glusterfs mounts is then bind-mounted inside the container. This avoids having
+to bind mount individual gluster volumes.
+
+The same needs to be updated in etc/sysconfig/swift-volumes.
+For example(in swift-volumes):
+GLUSTER_VOLUMES='tv1'
+
+Where tv1 is the volume name.
+
+**Example:**
+
+```bash
+# docker run -d --privileged  -v /sys/fs/cgroup/:/sys/fs/cgroup/:ro -p 8080:8080 -v /mnt/gluster-object:/mnt/gluster-object    gluster-swift
+```
+
+If you have selinux set to enforced on the host machine, refer to the
+Troubleshooting section below before running the container.
+
+**Note:**
+
+~~~
+-d : Runs the container in the background.
+-p : Publishes the container's port to the host port. They need not be the same.
+     If host port is omitted, a random port will be mapped. So you can run
+     multiple instances of the container, each serving on a different port on
+     the same host machine.
+-v : Bind mount a host path inside the container.
+-e : Set and pass environment variable. In our case, provide a list of volumes
+     to be exported over object inerface by setting GLUSTER_VOLUMES environment
+     variable.
+~~~
+
+### Custom deployment
+
+You can provide your own configuration files and ring files and have the
+swift processes running inside container use those. This can be done by
+placing your conf files and ring files in a directory on your host machine
+and then bind-mounting it inside the container at `/etc/swift`.
+
+**Example:**
+
+Assuming you have conf files and ring files present at `/tmp/swift` on the
+machine, you can spawn the container as follows:
+
+```bash
+# docker run -d -p 8080:8080 -v /tmp/swift:/etc/swift -v /mnt/gluster-object:/mnt/gluster-object prashanthpai/gluster-swift:dev
+```
+
+If the host machine has SELinux set to enforced:
+
+```bash
+# chcon -Rt svirt_sandbox_file_t /tmp/swift
+```
+
+### Troubleshooting
+
+**SELinux**
+
+When a volume is bind mounted inside the container, you'll need blessings of
+SELinux on the host machine. Otherwise, the application inside the container
+won't be able to access the volume. Example:
+
+```bash
+[root@f24 ~]# docker exec -i -t nostalgic_goodall /bin/bash
+[root@042abf4acc4d /]# ls /mnt/gluster-object/
+ls: cannot open directory /mnt/gluster-object/: Permission denied
+```
+
+Ideally, running this command on host machine should work:
+
+```bash
+# chcon -Rt svirt_sandbox_file_t /mnt/gluster-object
+```
+
+However, glusterfs does not support setting of SELinux contexts [yet][1].
+You can always set SELinux to permissive on host machine by running
+`setenforce 0` or run container in privileged mode (`--privileged=true`).
+I don't like either. A better workaround would be to mount the glusterfs
+volumes on host machine as shown in following example:
+
+[1]: https://bugzilla.redhat.com/show_bug.cgi?id=1252627
+
+```bash
+mount -t glusterfs -o selinux,context="system_u:object_r:svirt_sandbox_file_t:s0" `hostname`:test /mnt/gluster-object/test
+```
+
+### TODO
+
+* Install gluster-swift from RPMs. (Currently installed from source)