Add a script to generate the static inventory

We moved from dynamic to static inventory. When creating a new host with
launch-node, a script isn't really needed, the inventory is yaml, the
new host can just be added. However, generating a new inventory by
hitting the APIs of all of our clouds might be useful, so add a utility
script to help in case such a thing is needed.

Change-Id: Iae1be8e9cfe19533005e9f0395d1ef7a6427bc83

tools/generate-inventory.py

@@ -0,0 +1,72 @@
+#!/usr/bin/env python3
+# Copyright (c) 2018 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+#
+# This script generates a static inventory YAML file suitable for
+# ansible by querying the providers using the dynamic inventory
+# generator.  Previously we had ansible dynamically generate it's
+# inventory using it's openstack inventory generator plugin on each
+# run, but it was found to be somewhat unreliable if a single
+# cloud-provider became unavailable -- it would halt the whole ansible
+# run.
+#
+
+import argparse
+import logging
+import yaml
+import openstack
+import os
+import sys
+
+from openstack.cloud import inventory
+
+parser = argparse.ArgumentParser(
+    description='Generate a static inventory via a query of cloud providers')
+
+parser.add_argument("--debug", help="enable some debugging output",
+                    action="store_true")
+parser.add_argument("--output", help="output to file", default='openstack.yaml')
+parser.add_argument("--force", help="overwrite output file if exists",
+                    action="store_true")
+
+args = parser.parse_args()
+
+logging.basicConfig(level=logging.DEBUG if args.debug else logging.INFO)
+if args.debug:
+    openstack.enable_logging(debug=True)
+
+if os.path.exists(args.output) and not args.force:
+    logging.error("Refusing to overwrite output: %s" % args.output)
+    sys.exit(1)
+
+filtered_inv = {}
+logging.info("Querying inventory ...")
+inv = inventory.OpenStackInventory()
+for host in inv.list_hosts(expand=False):
+    logging.info("Found %s" % host['name'])
+    filtered_inv[host['name']] = dict(
+        ansible_host=host['interface_ip'],
+        public_v4=host['public_v4'],
+        private_v4=host['private_v4'],
+        public_v6=host['public_v6'],
+        )
+full = dict(all=dict(hosts=filtered_inv))
+logging.info("Writing output to: %s" % args.output)
+# note default_flow_style=False keeps everything in
+# block style, which is much more ansible-y
+yaml.dump(full, open(args.output, 'w'),
+          default_flow_style=False)
+logging.info("Done!")