Add support to generate a sample undercloud.conf

This is needed to kick off undercloud install with
--use-heat option. This includes new config options
to configure containerized undercloud along with
existing instack options.

Change-Id: Ibebaf068018a790afdb599e4e6fbc79d3b2a57dc
Partially-implements: blueprint heat-undercloud

config-generator/undercloud.conf

@@ -0,0 +1,3 @@
+[DEFAULT]
+output_file = undercloud.conf.sample
+namespace = undercloud_config

setup.cfg

@@ -99,3 +99,6 @@ openstack.tripleoclient.v1 =
     undercloud_deploy = tripleoclient.v1.undercloud_deploy:DeployUndercloud
     undercloud_install = tripleoclient.v1.undercloud:InstallUndercloud
     undercloud_upgrade = tripleoclient.v1.undercloud:UpgradeUndercloud
+
+oslo.config.opts =
+    undercloud_config  = tripleoclient.v1.undercloud_config:list_opts

tox.ini

@@ -52,5 +52,8 @@ show-source = True
 builtins = _
 exclude=.venv,.git,.tox,dist,doc,*openstack/common*,*lib/python*,*egg,build,releasenotes
 
+[testenv:genconfig]
+commands = oslo-config-generator --config-file config-generator/undercloud.conf
+
 [testenv:releasenotes]
 commands = bash -c tools/releasenotes_tox.sh

tripleoclient/v1/undercloud_config.py

@@ -15,6 +15,7 @@
 
 """Plugin action implementation"""
 
+import copy
 import logging
 import netaddr
 import os
@@ -358,6 +359,10 @@ CONF.register_opts(_opts)
 LOG = logging.getLogger(__name__ + ".undercloud_config")
 
 
+def list_opts():
+    return [(None, copy.deepcopy(_opts))]
+
+
 def _load_config():
     conf_params = []
     if os.path.isfile(PATHS.CONF_PATH):