Add profile argument

The patch implements --profile argument, which defines a path to
a profile.yaml file - a file which contains python-tempestconf
arguments and their values.
Also --generate-profile argument is introduced. A user can generate
a sample profile.yaml file using this argument. The sample contains
definitions of all python-tempestconf arguments set to their default
values.

Story: 2004503
Task: 28225

Change-Id: I80848d8ef9868ed3975b938d61880753eadc5ae9

config_tempest/profile.py

@@ -0,0 +1,103 @@
+# Copyright 2018 Red Hat, Inc.
+# All Rights Reserved.
+#
+# 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 yaml
+
+
+def _convert_remove_append(options):
+    """Convert append and remove dicts read from .yaml file.
+
+    :param options: {'section.key': 'value1,value2', ...}
+    :type options: dict
+    :return: ['section.key=value1,value2', ...]
+    :rtype: list
+    """
+    converted = []
+    for key in options:
+        v = options[key]
+        if isinstance(v, list):
+            v = ','.join(v)
+        converted.append(key + "=" + v)
+    return converted
+
+
+def read_profile_file(path):
+    """Read python-tempestconf arguments from a .yaml file.
+
+    :param path: path to the profile.yaml file
+    :type path: string
+    :return: profile arguments
+    :rtype: dict
+    """
+    with open(path, 'r') as stream:
+        profile_args = yaml.load(stream)
+    # convert overrides, to a list of tuples (s, k, v)
+    overrides = []
+    if 'overrides' in profile_args:
+        for key in profile_args['overrides']:
+            s, k = key.split('.')
+            v = profile_args['overrides'][key]
+            if isinstance(v, list):
+                v = ','.join(v)
+            overrides.append((s, k, v))
+    profile_args['overrides'] = overrides
+    # convert remove
+    remove = []
+    if 'remove' in profile_args:
+        remove = _convert_remove_append(profile_args['remove'])
+    profile_args['remove'] = remove
+    # convert append values
+    append = []
+    if 'append' in profile_args:
+        append = _convert_remove_append(profile_args['append'])
+    profile_args['append'] = append
+    return profile_args
+
+
+def generate_profile(args, path):
+    """Generates a sample profile.yaml file.
+
+    :type args: argparse.Namespace
+    :param path: Specifies where the sample file will be generated in.
+    :type path: string
+    """
+    iterable_args = vars(args)
+    # pop following arguments as they are written
+    # more detailed to the file below
+    iterable_args.pop('append')
+    iterable_args.pop('overrides')
+    iterable_args.pop('remove')
+    # pop profile as that shouldn't be in a profile.yaml
+    iterable_args.pop('profile')
+    with open(path, 'w') as outfile:
+        yaml.safe_dump(iterable_args, outfile, default_flow_style=False)
+        outfile.write("""append: {}
+  #identity.username: username
+  #compute-feature-enabled.api_extensions:
+  #  - dvr
+  #  - extension
+overrides: {}
+  #identity.username: username
+  #identity.password:
+  #  - my_password
+  #compute-feature-enabled.api_extensions:
+  #  - dvr
+  #  - extension
+remove: {}
+  #identity.username: username
+  #compute-feature-enabled.api_extensions:
+  #  - dvr
+  #  - extension
+""")