Top level argument parser with auth info assertion

Adds a top level argument parser with support for help option and
options for setting authentication information. Checks that
authentication information is supplied.

tuskarclient/shell.py

@@ -19,26 +19,59 @@ from __future__ import print_function
 import logging
 import logging.handlers
 import sys
+import tuskarclient.v1_0.argparsers
 
 logger = logging.getLogger(__name__)
 
 
 class TuskarShell(object):
 
-    def __init__(self, args):
-        self.args = args
+    def __init__(self, raw_args):
+        self.raw_args = raw_args
 
     def run(self):
-        pass
+        parser = tuskarclient.v1_0.argparsers.create_top_parser()
+        args = parser.parse_args(self.raw_args)
+
+        if args.help or not self.raw_args:
+            parser.print_help()
+            return 0
+
+        self._ensure_auth_info(args)
+
+    def _ensure_auth_info(self, args):
+        if not args.os_username:
+            raise UsageError("You must provide username via either "
+                             "--os-username or env[OS_USERNAME]")
+
+        if not args.os_password:
+            raise UsageError("You must provide password via either "
+                             "--os-password or env[OS_PASSWORD]")
+
+        if not args.os_tenant_id and not args.os_tenant_name:
+            raise UsageError("You must provide tenant via either "
+                             "--os-tenant-name or --os-tenant-id or "
+                             "env[OS_TENANT_NAME] or env[OS_TENANT_ID]")
+
+        if not args.os_auth_url:
+            raise UsageError("You must provide auth URL via either "
+                             "--os-auth-url or env[OS_AUTH_URL]")
+
+
+class UsageError(Exception):
+    pass
 
 
 def main():
     logger.addHandler(logging.StreamHandler(sys.stderr))
     try:
         TuskarShell(sys.argv[1:]).run()
+    except UsageError as e:
+        print(e.message, file=sys.stderr)
     except Exception as e:
         logger.exception("Exiting due to an error:")
         sys.exit(1)
 
+
 if __name__ == '__main__':
     main()

tuskarclient/utils.py

@@ -0,0 +1,26 @@
+#    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.
+
+import os
+
+
+def env(*vars, **kwargs):
+    """Search for the first defined of possibly many env vars
+
+    Returns the first environment variable defined in vars, or
+    returns the default defined in kwargs.
+    """
+    for v in vars:
+        value = os.environ.get(v, None)
+        if value:
+            return value
+    return kwargs.get('default', '')

tuskarclient/v1_0/argparsers.py

@@ -0,0 +1,73 @@
+#    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.
+
+import argparse
+import tuskarclient.utils as utils
+
+
+def create_top_parser():
+    parser = argparse.ArgumentParser(prog='tuskar',
+                                     description='OpenStack Management CLI',
+                                     add_help=False
+                                     )
+
+    parser.add_argument('-h', '--help',
+                        action='store_true',
+                        help="Print this help message and exit.",
+                        )
+
+    parser.add_argument('--os-username',
+                        default=utils.env('OS_USERNAME'),
+                        help='Defaults to env[OS_USERNAME]',
+                        )
+
+    parser.add_argument('--os_username',
+                        help=argparse.SUPPRESS,
+                        )
+
+    parser.add_argument('--os-password',
+                        default=utils.env('OS_PASSWORD'),
+                        help='Defaults to env[OS_PASSWORD]',
+                        )
+
+    parser.add_argument('--os_password',
+                        help=argparse.SUPPRESS,
+                        )
+
+    parser.add_argument('--os-tenant-id',
+                        default=utils.env('OS_TENANT_ID'),
+                        help='Defaults to env[OS_TENANT_ID]',
+                        )
+
+    parser.add_argument('--os_tenant_id',
+                        help=argparse.SUPPRESS,
+                        )
+
+    parser.add_argument('--os-tenant-name',
+                        default=utils.env('OS_TENANT_NAME'),
+                        help='Defaults to env[OS_TENANT_NAME]',
+                        )
+
+    parser.add_argument('--os_tenant_name',
+                        help=argparse.SUPPRESS,
+                        )
+
+    parser.add_argument('--os-auth-url',
+                        default=utils.env('OS_AUTH_URL'),
+                        help='Defaults to env[OS_AUTH_URL]',
+                        )
+
+    parser.add_argument('--os_auth_url',
+                        help=argparse.SUPPRESS,
+                        )
+
+    return parser