Oslo cfg backed by etcd example

oslo.cfg-etcd.bash

### The script which access oslo.cfg and print a value

chmouel@TheBatman:GIT/openstack/oslo.config$ cat ~/tmp/c.py                                                                                        [etcd]
import sys
from oslo.config import cfg


opt_group = cfg.OptGroup(name='simple', title='A Simple Example')

simple_opts = [
    cfg.StrOpt('hello', default="thedefaultvalue",
                help=('hello my beloved default')),
    cfg.BoolOpt('enable', default=True,
                help=('True enables, False disables'))
]

if __name__ == '__main__':
    conf = cfg.ConfigOpts()
    conf(args=sys.argv[1:], project='blah',
         default_config_files=[])

    conf.register_group(opt_group)
    conf.register_opts(simple_opts, opt_group)
    print conf.simple.hello

### Let's try launching it and asking to connect to the localhost etcd server,
### since we don't have anything in that etcd server it would get the default
### value from oslo config specified in the code
chmouel@TheBatman:GIT/openstack/oslo.config$ python ~/tmp/c.py --etcd-server localhost                                                             [etcd]
thedefaultvalue

### Now let's override it in etcd manually with etcdctl this is using etcdctl
### the base path is obviously going to be changed in the future
chmouel@TheBatman:GIT/openstack/oslo.config$ etcdctl mk /org/chmouel/simple/hello "Overridedbyetcd"                                                [etcd]
Overridedbyetcd

### Let's relaunch the script again and see if it got the value we overrided in etcd
chmouel@TheBatman:GIT/openstack/oslo.config$ python ~/tmp/c.py --etcd-server localhost                                                             [etcd]
Overridedbyetcd


### Kaboom!

Hey Chmouel Boudjnah, curious about your code, I reckon the '--etcd-server' option is not supported by oslo_config. How can you make it work?