Adding basic flask framework

Pending addition of Flask-OsloLog and Flask-KeystoneAuth

Change-Id: I734bcd4390d1eeadd61c64516ac6b0adf02d09e9

nemesis.conf.sample

@@ -0,0 +1,16 @@
+[DEFAULT]
+
+[keystone_authtoken]
+identity_uri = 
+auth_uri = 
+admin_tenant_name = 
+admin_user = 
+admin_password = 
+auth_version = 
+auth_protocol = 
+delay_auth_decision = True
+
+[sqlalchemy]
+database_uri = sqlite:////tmp/nemesis.db 
+echo = true
+

python_nemesis/base_app.py

@@ -0,0 +1,91 @@
+# 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.
+
+from flask import Flask
+import os
+from oslo_config import cfg
+from python_nemesis.config import collect_sqlalchemy_opts
+from python_nemesis.config import register_opts
+from python_nemesis.extensions import db
+# from python_nemesis.extensions import log
+
+
+def configure_blueprints(app, blueprints):
+    """Register configured blueprints into app object.
+
+    :param app: The application object to which configuration should
+                be applied.
+    :type app: :py:class:`flask.Flask`
+    :param blueprints: list of blueprints to be registered.
+    :type blueprints: list(:py:class:`flask.Blueprint`)
+    """
+    for blueprint in blueprints:
+        app.register_blueprint(blueprint)
+
+
+def configure_app(app):
+    """Retrieve App Configuration.
+
+    configure_app first loads default configuration and then attempts
+    to override defaults using a file specified in env:NEMESIS_CONFIG.
+
+    :param app: The application object to which configuration should
+                be applied.
+    :type app: :py:class:`flask.Flask`
+    """
+    app.config.from_object('python_nemesis.default_config')
+    app.config["cfg"] = cfg.CONF
+    config_file = os.environ.get(
+        "NEMESIS_CONFIG",
+        "/etc/nemesis/nemesis.conf")
+
+    register_opts(app.config["cfg"], config_file)
+    collect_sqlalchemy_opts(app, app.config["cfg"])
+
+
+def configure_extensions(app):
+    """Initialize extensions for Flask.
+
+    This function is intended for use with the app factory style
+    of Flask deployment.
+
+    :param app: The application object to which configuration should
+                be applied.
+    :type app: :py:class:`flask.Flask`
+    """
+    db.init_app(app)
+    # log.init_app(app)
+
+
+def create_app(app_name=None, blueprints=None):
+    """Create the flask app.
+
+    This function is intended to be used with the app factory
+    style of Flask deployment.
+
+    :param str app_name: Name to be used internally within flask.
+    :param blueprints: Blueprints to be registered.
+    :type blueprints: list(:py:class:`flask.Blueprint`)
+    :returns: The created app.
+    :rtype: :py:class:`flask.Flask`
+    """
+    app = Flask(app_name)
+
+    configure_app(app)
+    configure_extensions(app)
+
+    return app
+
+
+if __name__ == "__main__":  # pragma: no cover
+    app = create_app('nemesis-api')
+    app.run(threaded=True)

python_nemesis/config.py

@@ -0,0 +1,80 @@
+# 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.
+
+from oslo_config import cfg
+
+
+DEFAULT_OPT_GRP = cfg.OptGroup(name='DEFAULT')
+DEFAULT_OPTS = [
+    cfg.StrOpt('test_value', default="this is a value")
+]
+
+SQLALCHEMY_OPT_GRP = cfg.OptGroup(name='sqlalchemy')
+SQLALCHEMY_OPTS = [
+    cfg.StrOpt('database_uri'),
+    cfg.BoolOpt('echo'),
+    cfg.IntOpt('pool_size'),
+    cfg.IntOpt('pool_timeout'),
+    cfg.IntOpt('pool_recycle'),
+    cfg.IntOpt('max_overflow'),
+    cfg.BoolOpt('track_modifications'),
+]
+
+IDENTITY_OPT_GRP = cfg.OptGroup(name='identity')
+IDENTITY_OPTS = [
+    cfg.StrOpt('username'),
+    cfg.StrOpt('password')
+]
+
+
+def register_opts(conf, config_file):
+    '''Register Oslo Configuration Options from a provided config file.
+
+    :param conf: oslo config to be populated.
+    :type conf: :py:obj:`cfg.CONF`
+    :param str config_file: Location of the config file to be used.
+    '''
+    conf(default_config_files=[config_file])
+    conf.register_opts(DEFAULT_OPTS)
+    conf.register_group(SQLALCHEMY_OPT_GRP)
+    conf.register_opts(SQLALCHEMY_OPTS, SQLALCHEMY_OPT_GRP)
+    conf.register_group(IDENTITY_OPT_GRP)
+    conf.register_opts(IDENTITY_OPTS, IDENTITY_OPT_GRP)
+
+
+def collect_sqlalchemy_opts(app, conf):
+    """Collect sqlalchemy options from `oslo.config` and apply them.
+
+    This function copies the configuration entries for sqlalchemy
+    directly into the :py:class:`flask.Flask` object where the
+    upstream Flask-SqlAlchemy extension expects to find them.
+
+    :param app: The application object to which configuration should
+                be applied.
+    :type app: :py:class:`flask.Flask`
+    :param conf: oslo config to be populated.
+    :type conf: :py:obj:`cfg.CONF`
+    """
+    def _import_opt_from_oslo(flask_opt, oslo_opt):
+        if conf.sqlalchemy[oslo_opt] is not None:
+            app.config[flask_opt] = conf.sqlalchemy[oslo_opt]
+
+    _import_opt_from_oslo('SQLALCHEMY_DATABASE_URI', 'database_uri')
+    _import_opt_from_oslo('SQLALCHEMY_ECHO', 'echo')
+    _import_opt_from_oslo('SQLALCHEMY_POOL_SIZE', 'pool_size')
+    _import_opt_from_oslo('SQLALCHEMY_POOL_TIMEOUT', 'pool_timeout')
+    _import_opt_from_oslo('SQLALCHEMY_POOL_RECYCLE', 'pool_recycle')
+    _import_opt_from_oslo('SQLALCHEMY_MAX_OVERFLOW', 'max_overflow')
+    _import_opt_from_oslo(
+        'SQLALCHEMY_TRACK_MODIFICATIONS',
+        'track_modifications'
+    )

python_nemesis/default_config.py

@@ -0,0 +1,4 @@
+DEBUG = True
+TESTING = False
+JSONIFY_PRETTYPRINT_REGULAR = True
+JSON_SORT_KEYS = True

python_nemesis/extensions.py

@@ -0,0 +1,6 @@
+# from flask_oslolog import OsloLog
+from flask_sqlalchemy import SQLAlchemy
+
+
+db = SQLAlchemy()
+# log = OsloLog()

requirements.txt

@@ -3,3 +3,10 @@
 # process, which may cause wedges in the gate later.
 
 pbr>=2.0.0 # Apache-2.0
+alembic>=0.8.10 # MIT
+Flask!=0.11,<1.0,>=0.10 # BSD
+Flask-SQLAlchemy>=2.0 # BSD
+oslo.config>=3.22.0 # Apache-2.0
+oslo.messaging>=5.19.0 # Apache-2.0
+oslo.log>=3.11.0 # Apache-2.0
+keystonemiddleware>=4.12.0 # Apache-2.0