diff --git a/savanna/api/v10.py b/savanna/api/v10.py
index 84c99b51..6cd2ac61 100644
--- a/savanna/api/v10.py
+++ b/savanna/api/v10.py
@@ -16,7 +16,7 @@
 from savanna.openstack.common import log as logging
 from savanna.service import api
 import savanna.utils.api as u
-from savanna.utils.openstack.nova import novaclient
+from savanna.utils.openstack import nova
 
 LOG = logging.getLogger(__name__)
 
@@ -135,34 +135,34 @@ def plugins_get_version(plugin_name, version):
 @rest.get('/images')
 def images_list():
     return u.render(
-        images=[i.dict for i in novaclient().images.list_registered()])
+        images=[i.dict for i in nova.client().images.list_registered()])
 
 
 @rest.get('/images/<image_id>')
 def images_get(image_id):
-    return u.render(novaclient().images.get(image_id).dict)
+    return u.render(nova.client().images.get(image_id).dict)
 
 
-def _render_image(image_id, nova):
-    return u.render(nova.images.get(image_id).wrapped_dict)
+def _render_image(image_id, novaclient):
+    return u.render(novaclient.images.get(image_id).wrapped_dict)
 
 
 @rest.post('/images/<image_id>')
 def images_set(image_id, data):
-    nova = novaclient()
-    nova.images.set_description(image_id, **data)
-    return _render_image(image_id, nova)
+    novaclient = nova.client()
+    novaclient.images.set_description(image_id, **data)
+    return _render_image(image_id, novaclient)
 
 
 @rest.post('/images/<image_id>/tag')
 def image_tags_add(image_id, data):
-    nova = novaclient()
-    nova.images.tag(image_id, **data)
-    return _render_image(image_id, nova)
+    novaclient = nova.client()
+    novaclient.images.tag(image_id, **data)
+    return _render_image(image_id, novaclient)
 
 
 @rest.post('/images/<image_id>/untag')
 def image_tags_delete(image_id, data):
-    nova = novaclient()
-    nova.images.untag(image_id, **data)
-    return _render_image(image_id, nova)
+    novaclient = nova.client()
+    novaclient.images.untag(image_id, **data)
+    return _render_image(image_id, novaclient)
diff --git a/savanna/context.py b/savanna/context.py
index a285e18d..cb922d49 100644
--- a/savanna/context.py
+++ b/savanna/context.py
@@ -51,6 +51,15 @@ def ctx():
     return _CTXS._curr_ctx
 
 
+def current():
+    return ctx()
+
+
+def session(context=None):
+    context = context or ctx()
+    return context.session
+
+
 def set_ctx(new_ctx):
     if not new_ctx and hasattr(_CTXS, '_curr_ctx'):
         del _CTXS._curr_ctx
diff --git a/savanna/db/migration/alembic_migrations/env.py b/savanna/db/migration/alembic_migrations/env.py
index a55dbcd8..5dc32164 100644
--- a/savanna/db/migration/alembic_migrations/env.py
+++ b/savanna/db/migration/alembic_migrations/env.py
@@ -14,7 +14,7 @@
 # limitations under the License.
 
 from alembic import context
-from logging.config import fileConfig
+from logging import config as logging_config
 from savanna.openstack.common import importutils
 from sqlalchemy import create_engine, pool
 
@@ -26,7 +26,7 @@ importutils.import_module('savanna.db.models')
 config = context.config
 savanna_config = config.savanna_config
 
-fileConfig(config.config_file_name)
+logging_config.fileConfig(config.config_file_name)
 
 # set the target for 'autogenerate' support
 target_metadata = model_base.SavannaBase.metadata
diff --git a/savanna/db/migration/alembic_migrations/versions/v02_initial.py b/savanna/db/migration/alembic_migrations/versions/v02_initial.py
index 47e16b40..062e0c76 100644
--- a/savanna/db/migration/alembic_migrations/versions/v02_initial.py
+++ b/savanna/db/migration/alembic_migrations/versions/v02_initial.py
@@ -28,9 +28,9 @@ down_revision = None
 from alembic import op
 import sqlalchemy as sa
 
-from savanna.utils.sqlatypes import JSONEncoded
+from savanna.utils import sqlatypes as st
 
-sa.JSONEncoded = JSONEncoded
+sa.JSONEncoded = st.JSONEncoded
 
 
 def upgrade():
diff --git a/savanna/db/model_base.py b/savanna/db/model_base.py
index 1869e2f2..e3791bb9 100644
--- a/savanna/db/model_base.py
+++ b/savanna/db/model_base.py
@@ -12,6 +12,7 @@
 # implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+
 import re
 
 import sqlalchemy as sa
@@ -20,11 +21,11 @@ from sqlalchemy import orm
 
 from savanna.openstack.common import timeutils
 from savanna.openstack.common import uuidutils
-from savanna.utils.resources import BaseResource
-from savanna.utils.sqlatypes import JsonDictType
+from savanna.utils import resources
+from savanna.utils import sqlatypes as st
 
 
-class _SavannaBase(BaseResource):
+class _SavannaBase(resources.BaseResource):
     """Base class for all Savanna Models."""
 
     created = sa.Column(sa.DateTime, default=timeutils.utcnow,
@@ -140,4 +141,4 @@ class ExtraMixin(object):
 
     __filter_cols__ = ['extra']
 
-    extra = sa.Column(JsonDictType())
+    extra = sa.Column(st.JsonDictType())
diff --git a/savanna/db/models.py b/savanna/db/models.py
index 094da7cb..f333088d 100644
--- a/savanna/db/models.py
+++ b/savanna/db/models.py
@@ -19,10 +19,9 @@ from sqlalchemy.orm import relationship
 
 from savanna.db import model_base as mb
 from savanna.utils import crypto
-from savanna.utils.openstack.nova import novaclient
+from savanna.utils.openstack import nova
 from savanna.utils import remote
-from savanna.utils.sqlatypes import JsonDictType
-from savanna.utils.sqlatypes import JsonListType
+from savanna.utils import sqlatypes as st
 
 
 CLUSTER_STATUSES = ['Starting', 'Active', 'Stopping', 'Error']
@@ -39,7 +38,7 @@ class Cluster(mb.SavannaBase, mb.IdMixin, mb.TenantMixin,
 
     name = sa.Column(sa.String(80), nullable=False)
     default_image_id = sa.Column(sa.String(36))
-    cluster_configs = sa.Column(JsonDictType())
+    cluster_configs = sa.Column(st.JsonDictType())
     node_groups = relationship('NodeGroup', cascade="all,delete",
                                backref='cluster')
     # todo replace String type with sa.Enum(*CLUSTER_STATUSES)
@@ -76,7 +75,7 @@ class Cluster(mb.SavannaBase, mb.IdMixin, mb.TenantMixin,
         It contains 'public_key' and 'fingerprint' fields.
         """
         if not hasattr(self, '_user_kp'):
-            self._user_kp = novaclient().keypairs.get(self.user_keypair_id)
+            self._user_kp = nova.client().keypairs.get(self.user_keypair_id)
         return self._user_kp
 
 
@@ -92,8 +91,8 @@ class NodeGroup(mb.SavannaBase, mb.IdMixin, mb.ExtraMixin):
     name = sa.Column(sa.String(80), nullable=False)
     flavor_id = sa.Column(sa.String(36), nullable=False)
     image_id = sa.Column(sa.String(36), nullable=False)
-    node_processes = sa.Column(JsonListType())
-    node_configs = sa.Column(JsonDictType())
+    node_processes = sa.Column(st.JsonListType())
+    node_configs = sa.Column(st.JsonDictType())
     anti_affinity_group = sa.Column(sa.String(36))
     count = sa.Column(sa.Integer, nullable=False)
     instances = relationship('Instance', cascade="all,delete",
@@ -119,7 +118,7 @@ class NodeGroup(mb.SavannaBase, mb.IdMixin, mb.ExtraMixin):
     @property
     def username(self):
         if not hasattr(self, '_username'):
-            self._username = novaclient().images.get(self.image_id).username
+            self._username = nova.client().images.get(self.image_id).username
         return self._username
 
     @property
@@ -166,7 +165,7 @@ class Instance(mb.SavannaBase, mb.ExtraMixin):
     @property
     def nova_info(self):
         """Returns info from nova about instance."""
-        return novaclient().servers.get(self.instance_id)
+        return nova.client().servers.get(self.instance_id)
 
     @property
     def username(self):
@@ -191,7 +190,7 @@ class ClusterTemplate(mb.SavannaBase, mb.IdMixin, mb.TenantMixin,
 
     name = sa.Column(sa.String(80), nullable=False)
     description = sa.Column(sa.String(200))
-    cluster_configs = sa.Column(JsonDictType())
+    cluster_configs = sa.Column(st.JsonDictType())
 
     # todo add node_groups_suggestion helper
 
@@ -228,8 +227,8 @@ class NodeGroupTemplate(mb.SavannaBase, mb.IdMixin, mb.TenantMixin,
     name = sa.Column(sa.String(80), nullable=False)
     description = sa.Column(sa.String(200))
     flavor_id = sa.Column(sa.String(36), nullable=False)
-    node_processes = sa.Column(JsonListType())
-    node_configs = sa.Column(JsonDictType())
+    node_processes = sa.Column(st.JsonListType())
+    node_configs = sa.Column(st.JsonDictType())
 
     def __init__(self, name, tenant_id, flavor_id, plugin_name,
                  hadoop_version, node_processes, node_configs=None,
diff --git a/savanna/db/storage.py b/savanna/db/storage.py
index 2e0fb33a..d158ddf2 100644
--- a/savanna/db/storage.py
+++ b/savanna/db/storage.py
@@ -13,8 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from savanna.context import ctx
-from savanna.context import model_query
+from savanna import context as ctx
 import savanna.db.models as m
 
 
@@ -22,17 +21,17 @@ import savanna.db.models as m
 # todo check tenant_id and etc.
 
 def get_clusters(**args):
-    return model_query(m.Cluster).filter_by(**args).all()
+    return ctx.model_query(m.Cluster).filter_by(**args).all()
 
 
 def get_cluster(**args):
-    return model_query(m.Cluster).filter_by(**args).first()
+    return ctx.model_query(m.Cluster).filter_by(**args).first()
 
 
 def create_cluster(values):
-    session = ctx().session
+    session = ctx.current().session
     with session.begin():
-        values['tenant_id'] = ctx().tenant_id
+        values['tenant_id'] = ctx.current().tenant_id
         ngs_vals = values.pop('node_groups', [])
         cluster = m.Cluster(**values)
         for ng in ngs_vals:
@@ -45,24 +44,24 @@ def create_cluster(values):
 
 
 def terminate_cluster(cluster):
-    with ctx().session.begin():
-        ctx().session.delete()
+    with ctx.current().session.begin():
+        ctx.current().session.delete(cluster)
 
 
 ## ClusterTemplate ops
 
 def get_cluster_templates(**args):
-    return model_query(m.ClusterTemplate).filter_by(**args).all()
+    return ctx.model_query(m.ClusterTemplate).filter_by(**args).all()
 
 
 def get_cluster_template(**args):
-    return model_query(m.ClusterTemplate).filter_by(**args).first()
+    return ctx.model_query(m.ClusterTemplate).filter_by(**args).first()
 
 
 def create_cluster_template(values):
-    session = ctx().session
+    session = ctx.current().session
     with session.begin():
-        values['tenant_id'] = ctx().tenant_id
+        values['tenant_id'] = ctx.current().tenant_id
         ngts_vals = values.pop('node_group_templates', [])
         cluster_template = m.ClusterTemplate(**values)
         for ngt in ngts_vals:
@@ -76,29 +75,29 @@ def create_cluster_template(values):
 
 
 def terminate_cluster_template(**args):
-    with ctx().session.begin():
-        ctx().session.delete(get_cluster_template(**args))
+    with ctx.current().session.begin():
+        ctx.current().session.delete(get_cluster_template(**args))
 
 
 ## NodeGroupTemplate ops
 
 def get_node_group_templates(**args):
-    return model_query(m.NodeGroupTemplate).filter_by(**args).all()
+    return ctx.model_query(m.NodeGroupTemplate).filter_by(**args).all()
 
 
 def get_node_group_template(**args):
-    return model_query(m.NodeGroupTemplate).filter_by(**args).first()
+    return ctx.model_query(m.NodeGroupTemplate).filter_by(**args).first()
 
 
 def create_node_group_template(values):
-    session = ctx().session
+    session = ctx.current().session
     with session.begin():
-        values['tenant_id'] = ctx().tenant_id
+        values['tenant_id'] = ctx.current().tenant_id
         node_group_template = m.NodeGroupTemplate(**values)
         session.add(node_group_template)
         return node_group_template
 
 
 def terminate_node_group_template(**args):
-    with ctx().session.begin():
-        ctx().session.delete(get_node_group_template(**args))
+    with ctx.current().session.begin():
+        ctx.current().session.delete(get_node_group_template(**args))
diff --git a/savanna/main.py b/savanna/main.py
index d45b270a..a16fe332 100644
--- a/savanna/main.py
+++ b/savanna/main.py
@@ -13,26 +13,26 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from eventlet import monkey_patch
-from flask import Flask
-from keystoneclient.middleware.auth_token import filter_factory as auth_token
+import eventlet
+import flask
+from keystoneclient.middleware import auth_token
 from oslo.config import cfg
-from savanna.context import ctx
-from savanna.plugins.base import setup_plugins
-from werkzeug.exceptions import default_exceptions
-from werkzeug.exceptions import HTTPException
+from werkzeug import exceptions as werkzeug_exceptions
 
 from savanna.api import v10 as api_v10
+from savanna import context
 from savanna.db import api as db_api
-from savanna.middleware.auth_valid import filter_factory as auth_valid
-from savanna.utils.api import render
-from savanna.utils.scheduler import setup_scheduler
+from savanna.middleware import auth_valid
+from savanna.plugins import base as plugins_base
+from savanna.utils import api as api_utils
+from savanna.utils import scheduler
 
 from savanna.openstack.common import log
 
 LOG = log.getLogger(__name__)
 
-monkey_patch(os=True, select=True, socket=True, thread=True, time=True)
+eventlet.monkey_patch(
+    os=True, select=True, socket=True, thread=True, time=True)
 
 opts = [
     cfg.StrOpt('os_auth_protocol',
@@ -67,11 +67,11 @@ def make_app():
 
     Entry point for Savanna REST API server
     """
-    app = Flask('savanna.api')
+    app = flask.Flask('savanna.api')
 
     @app.route('/', methods=['GET'])
     def version_list():
-        return render({
+        return api_utils.render({
             "versions": [
                 {"id": "v1.0", "status": "CURRENT"}
             ]
@@ -80,32 +80,33 @@ def make_app():
     @app.teardown_request
     def teardown_request(_ex=None):
         # todo how it'll work in case of exception?
-        session = ctx().session
+        session = context.session()
         if session.transaction:
             session.transaction.commit()
 
     app.register_blueprint(api_v10.rest, url_prefix='/v1.0')
 
     db_api.configure_db()
-    setup_scheduler(app)
-    setup_plugins()
+    scheduler.setup_scheduler(app)
+    plugins_base.setup_plugins()
 
     def make_json_error(ex):
         status_code = (ex.code
-                       if isinstance(ex, HTTPException)
+                       if isinstance(ex, werkzeug_exceptions.HTTPException)
                        else 500)
         description = (ex.description
-                       if isinstance(ex, HTTPException)
+                       if isinstance(ex, werkzeug_exceptions.HTTPException)
                        else str(ex))
-        return render({'error': status_code, 'error_message': description},
-                      status=status_code)
+        return api_utils.render({'error': status_code,
+                                 'error_message': description},
+                                status=status_code)
 
-    for code in default_exceptions.iterkeys():
+    for code in werkzeug_exceptions.default_exceptions.iterkeys():
         app.error_handler_spec[None][code] = make_json_error
 
-    app.wsgi_app = auth_valid(app.config)(app.wsgi_app)
+    app.wsgi_app = auth_valid.filter_factory(app.config)(app.wsgi_app)
 
-    app.wsgi_app = auth_token(
+    app.wsgi_app = auth_token.filter_factory(
         app.config,
         auth_host=CONF.os_auth_host,
         auth_port=CONF.os_auth_port,
diff --git a/savanna/plugins/base.py b/savanna/plugins/base.py
index 4e776243..d7a907ef 100644
--- a/savanna/plugins/base.py
+++ b/savanna/plugins/base.py
@@ -13,14 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from abc import ABCMeta
-from abc import abstractmethod
+import abc
 import inspect
+
 from oslo.config import cfg
-from savanna.config import parse_configs
+
+from savanna import config
 from savanna.openstack.common import importutils
 from savanna.openstack.common import log as logging
-from savanna.utils.resources import BaseResource
+from savanna.utils import resources
 
 LOG = logging.getLogger(__name__)
 
@@ -34,8 +35,8 @@ CONF = cfg.CONF
 CONF.register_opts(opts)
 
 
-class PluginInterface(BaseResource):
-    __metaclass__ = ABCMeta
+class PluginInterface(resources.BaseResource):
+    __metaclass__ = abc.ABCMeta
 
     name = 'plugin_interface'
 
@@ -59,7 +60,7 @@ class PluginInterface(BaseResource):
         """
         pass
 
-    @abstractmethod
+    @abc.abstractmethod
     def get_title(self):
         """Plugin title
 
@@ -102,13 +103,13 @@ class PluginManager(object):
             ]
             CONF.register_opts(opts, group='plugin:%s' % plugin)
 
-        parse_configs()
+        config.parse_configs()
 
         # register plugin-specific configs
         for plugin_name in CONF.plugins:
             self.plugins[plugin_name] = self._get_plugin_instance(plugin_name)
 
-        parse_configs()
+        config.parse_configs()
 
         titles = []
         for plugin_name in CONF.plugins:
diff --git a/savanna/plugins/provisioning.py b/savanna/plugins/provisioning.py
index dc3aaaa7..1c4edf9a 100644
--- a/savanna/plugins/provisioning.py
+++ b/savanna/plugins/provisioning.py
@@ -13,32 +13,33 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from abc import abstractmethod
+import abc
 import functools
-from savanna.plugins.base import PluginInterface
-import savanna.utils.openstack.nova as nova
-from savanna.utils.resources import BaseResource
+
+from savanna.plugins import base as plugins_base
+from savanna.utils.openstack import nova
+from savanna.utils import resources
 
 
 class ProvisioningPluginContext(object):
     def __init__(self, headers):
         self.headers = headers
-        self.nova = self._autoheaders(nova.novaclient)
+        self.nova = self._autoheaders(nova.client)
 
     def _autoheaders(self, func):
         return functools.partial(func, headers=self.headers)
 
 
-class ProvisioningPluginBase(PluginInterface):
-    @abstractmethod
+class ProvisioningPluginBase(plugins_base.PluginInterface):
+    @abc.abstractmethod
     def get_versions(self):
         pass
 
-    @abstractmethod
+    @abc.abstractmethod
     def get_configs(self, hadoop_version):
         pass
 
-    @abstractmethod
+    @abc.abstractmethod
     def get_node_processes(self, hadoop_version):
         pass
 
@@ -48,11 +49,11 @@ class ProvisioningPluginBase(PluginInterface):
     def update_infra(self, cluster):
         pass
 
-    @abstractmethod
+    @abc.abstractmethod
     def configure_cluster(self, cluster):
         pass
 
-    @abstractmethod
+    @abc.abstractmethod
     def start_cluster(self, cluster):
         pass
 
@@ -68,7 +69,7 @@ class ProvisioningPluginBase(PluginInterface):
         return res
 
 
-class Config(BaseResource):
+class Config(resources.BaseResource):
     """Describes a single config parameter.
 
     For example:
diff --git a/savanna/plugins/vanilla/plugin.py b/savanna/plugins/vanilla/plugin.py
index af5bb57e..91e8850a 100644
--- a/savanna/plugins/vanilla/plugin.py
+++ b/savanna/plugins/vanilla/plugin.py
@@ -13,11 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from savanna.plugins.provisioning import Config
-from savanna.plugins.provisioning import ProvisioningPluginBase
+from savanna.plugins import provisioning as p
 
 
-class VanillaProvider(ProvisioningPluginBase):
+class VanillaProvider(p.ProvisioningPluginBase):
     def get_plugin_opts(self):
         return []
 
@@ -37,7 +36,7 @@ class VanillaProvider(ProvisioningPluginBase):
 
     def get_configs(self, hadoop_version):
         return [
-            Config('heap_size', 'tasktracker', default_value='1024M')
+            p.Config('heap_size', 'tasktracker', default_value='1024M')
         ]
 
     def get_node_processes(self, hadoop_version):
diff --git a/savanna/service/api.py b/savanna/service/api.py
index 347ed731..abbb9875 100644
--- a/savanna/service/api.py
+++ b/savanna/service/api.py
@@ -14,10 +14,10 @@
 # limitations under the License.
 
 from savanna import context
-import savanna.db.storage as s
+from savanna.db import storage as s
 from savanna.openstack.common import log as logging
-import savanna.plugins.base as plugin_base
-from savanna.plugins.provisioning import ProvisioningPluginBase
+from savanna.plugins import base as plugin_base
+from savanna.plugins import provisioning
 from savanna.service import instances as i
 
 LOG = logging.getLogger(__name__)
@@ -98,7 +98,8 @@ terminate_node_group_template = s.terminate_node_group_template
 ## Plugins ops
 
 def get_plugins():
-    return plugin_base.PLUGINS.get_plugins(base=ProvisioningPluginBase)
+    return plugin_base.PLUGINS.get_plugins(
+        base=provisioning.ProvisioningPluginBase)
 
 
 def get_plugin(plugin_name, version=None):
diff --git a/savanna/service/instances.py b/savanna/service/instances.py
index 4e9f6cbd..76c2d251 100644
--- a/savanna/service/instances.py
+++ b/savanna/service/instances.py
@@ -18,8 +18,8 @@ import time
 from savanna import context
 from savanna.db import models as m
 from savanna.openstack.common import log as logging
-from savanna.utils.crypto import private_key_to_public_key
-import savanna.utils.openstack.nova as nova
+from savanna.utils import crypto
+from savanna.utils.openstack import nova
 
 LOG = logging.getLogger(__name__)
 
@@ -57,7 +57,7 @@ def _create_instances(cluster):
             ids = aa_groups[aa_group]
             hints = {'different_host': list(ids)} if ids else None
 
-            nova_instance = nova.novaclient().servers.create(
+            nova_instance = nova.client().servers.create(
                 name, node_group.image_id, node_group.flavor_id,
                 scheduler_hints=hints, files=files)
 
@@ -80,7 +80,7 @@ def _generate_instance_files(node_group):
         path_to_root = "/home/" + node_group.username
 
     authorized_keys = user_key.public_key + '\n'
-    authorized_keys += private_key_to_public_key(cluster.private_key)
+    authorized_keys += crypto.private_key_to_public_key(cluster.private_key)
 
     return {
         path_to_root + "/.ssh/authorized_keys": authorized_keys,
@@ -173,7 +173,7 @@ def _shutdown_instances(cluster, quiet=False):
     """Shutdown all instances related to the specified cluster."""
     for node_group in cluster.node_groups:
         for instance in node_group.instances:
-            nova.novaclient().servers.delete(instance.instance_id)
+            nova.client().servers.delete(instance.instance_id)
 
 
 def shutdown_cluster(cluster):
diff --git a/savanna/tests/unit/db/models/base.py b/savanna/tests/unit/db/models/base.py
index 7ada9c56..cd8bbfc6 100644
--- a/savanna/tests/unit/db/models/base.py
+++ b/savanna/tests/unit/db/models/base.py
@@ -18,10 +18,8 @@ import os
 import tempfile
 import unittest2
 
-from savanna.context import Context
-from savanna.context import set_ctx
-from savanna.db.api import clear_db
-from savanna.db.api import configure_db
+from savanna import context
+from savanna.db import api as db_api
 from savanna.openstack.common.db.sqlalchemy import session
 from savanna.openstack.common import timeutils
 from savanna.openstack.common import uuidutils
@@ -29,16 +27,17 @@ from savanna.openstack.common import uuidutils
 
 class ModelTestCase(unittest2.TestCase):
     def setUp(self):
-        set_ctx(Context('test_user', 'test_tenant', 'test_auth_token', {}))
+        context.set_ctx(
+            context.Context('test_user', 'test_tenant', 'test_auth_token', {}))
         self.db_fd, self.db_path = tempfile.mkstemp()
         session.set_defaults('sqlite:///' + self.db_path, self.db_path)
-        configure_db()
+        db_api.configure_db()
 
     def tearDown(self):
-        clear_db()
+        db_api.clear_db()
         os.close(self.db_fd)
         os.unlink(self.db_path)
-        set_ctx(None)
+        context.set_ctx(None)
 
     def assertIsValidModelObject(self, res):
         self.assertIsNotNone(res)
diff --git a/savanna/tests/unit/db/models/test_clusters.py b/savanna/tests/unit/db/models/test_clusters.py
index ca8c16db..87f6bb37 100644
--- a/savanna/tests/unit/db/models/test_clusters.py
+++ b/savanna/tests/unit/db/models/test_clusters.py
@@ -13,14 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from savanna.context import ctx
-import savanna.db.models as m
-from savanna.tests.unit.db.models.base import ModelTestCase
+from savanna import context as ctx
+from savanna.db import models as m
+from savanna.tests.unit.db.models import base as models_test_base
 
 
-class ClusterModelTest(ModelTestCase):
+class ClusterModelTest(models_test_base.ModelTestCase):
     def testCreateCluster(self):
-        session = ctx().session
+        session = ctx.current().session
         with session.begin():
             c = m.Cluster('c-1', 't-1', 'p-1', 'hv-1')
             session.add(c)
diff --git a/savanna/tests/unit/db/models/test_templates.py b/savanna/tests/unit/db/models/test_templates.py
index e12cca1e..391beaa3 100644
--- a/savanna/tests/unit/db/models/test_templates.py
+++ b/savanna/tests/unit/db/models/test_templates.py
@@ -12,13 +12,14 @@
 # implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from savanna.context import ctx
-
-import savanna.db.models as m
-from savanna.tests.unit.db.models.base import ModelTestCase
 
 import unittest2
 
+from savanna import context as ctx
+import savanna.db.models as m
+from savanna.tests.unit.db.models import base as models_test_base
+
+
 SAMPLE_CONFIGS = {
     'a': 'av',
     'b': 123,
@@ -26,9 +27,9 @@ SAMPLE_CONFIGS = {
 }
 
 
-class TemplatesModelTest(ModelTestCase):
+class TemplatesModelTest(models_test_base.ModelTestCase):
     def testCreateNodeGroupTemplate(self):
-        session = ctx().session
+        session = ctx.current().session
         with session.begin():
             ngt = m.NodeGroupTemplate('ngt-1', 't-1', 'f-1', 'p-1', 'hv-1',
                                       ['np-1', 'np-2'], SAMPLE_CONFIGS, "d")
@@ -53,7 +54,7 @@ class TemplatesModelTest(ModelTestCase):
         })
 
     def testCreateClusterTemplate(self):
-        session = ctx().session
+        session = ctx.current().session
         with session.begin():
             c = m.ClusterTemplate('c-1', 't-1', 'p-1', 'hv-1', SAMPLE_CONFIGS,
                                   "d")
@@ -75,7 +76,7 @@ class TemplatesModelTest(ModelTestCase):
         })
 
     def testCreateClusterTemplateWithNodeGroupTemplates(self):
-        session = ctx().session
+        session = ctx.current().session
         with session.begin():
             ct = m.ClusterTemplate('ct', 't-1', 'p-1', 'hv-1')
             session.add(ct)
diff --git a/savanna/tests/unit/service/test_instances.py b/savanna/tests/unit/service/test_instances.py
index 66e06dd2..12961a2b 100644
--- a/savanna/tests/unit/service/test_instances.py
+++ b/savanna/tests/unit/service/test_instances.py
@@ -14,15 +14,16 @@
 # limitations under the License.
 
 import mock
-import savanna.context as ctx
+
+from savanna import context as ctx
 import savanna.db.models as m
-from savanna.service.instances import _create_instances
-from savanna.tests.unit.db.models.base import ModelTestCase
+from savanna.service import instances
+from savanna.tests.unit.db.models import base as models_test_base
 import savanna.utils.crypto as c
 
 
-class NodePlacementTest(ModelTestCase):
-    @mock.patch('savanna.utils.openstack.nova.novaclient')
+class NodePlacementTest(models_test_base.ModelTestCase):
+    @mock.patch('savanna.utils.openstack.nova.client')
     def test_one_node_groups_and_one_affinity_group(self, novaclient):
         node_groups = [m.NodeGroup("test_group",
                                    "test_flavor",
@@ -36,7 +37,7 @@ class NodePlacementTest(ModelTestCase):
 
         nova = _create_nova_mock(novaclient)
 
-        _create_instances(cluster)
+        instances._create_instances(cluster)
         files = _generate_files(cluster)
 
         nova.servers.create.assert_has_calls(
@@ -56,7 +57,7 @@ class NodePlacementTest(ModelTestCase):
         with session.begin():
             self.assertEqual(session.query(m.Instance).count(), 2)
 
-    @mock.patch('savanna.utils.openstack.nova.novaclient')
+    @mock.patch('savanna.utils.openstack.nova.client')
     def test_one_node_groups_and_no_affinity_group(self, novaclient):
         node_groups = [m.NodeGroup("test_group",
                                    "test_flavor",
@@ -69,7 +70,7 @@ class NodePlacementTest(ModelTestCase):
 
         nova = _create_nova_mock(novaclient)
 
-        _create_instances(cluster)
+        instances._create_instances(cluster)
 
         files = _generate_files(cluster)
         nova.servers.create.assert_has_calls(
@@ -89,7 +90,7 @@ class NodePlacementTest(ModelTestCase):
         with session.begin():
             self.assertEqual(session.query(m.Instance).count(), 2)
 
-    @mock.patch('savanna.utils.openstack.nova.novaclient')
+    @mock.patch('savanna.utils.openstack.nova.client')
     def test_two_node_groups_and_one_affinity_group(self, novaclient):
         node_groups = [m.NodeGroup("test_group_1",
                                    "test_flavor",
@@ -110,7 +111,7 @@ class NodePlacementTest(ModelTestCase):
         cluster = _create_cluster_mock(node_groups)
         nova = _create_nova_mock(novaclient)
 
-        _create_instances(cluster)
+        instances._create_instances(cluster)
 
         files = _generate_files(cluster)
         nova.servers.create.assert_has_calls(
diff --git a/savanna/tests/unit/test_patches.py b/savanna/tests/unit/test_patches.py
index 16d4af59..00e54393 100644
--- a/savanna/tests/unit/test_patches.py
+++ b/savanna/tests/unit/test_patches.py
@@ -13,14 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from savanna.utils.patches import patch_minidom_writexml
-import unittest
+import unittest2
 import xml.dom.minidom as xml
 
+from savanna.utils import patches
 
-class MinidomPatchesTest(unittest.TestCase):
+
+class MinidomPatchesTest(unittest2.TestCase):
     def setUp(self):
-        patch_minidom_writexml()
+        patches.patch_minidom_writexml()
 
     def _generate_n_prettify_xml(self):
         doc = xml.Document()
diff --git a/savanna/utils/api.py b/savanna/utils/api.py
index 1e7ad030..35712ae5 100644
--- a/savanna/utils/api.py
+++ b/savanna/utils/api.py
@@ -13,21 +13,21 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import flask as f
 import inspect
 import mimetypes
 import traceback
-from werkzeug.datastructures import MIMEAccept
 
-from savanna.context import Context
-from savanna.context import set_ctx
+import flask
+from werkzeug import datastructures
+
+from savanna import context
 from savanna.openstack.common import log as logging
 from savanna.openstack.common import wsgi
 
 LOG = logging.getLogger(__name__)
 
 
-class Rest(f.Blueprint):
+class Rest(flask.Blueprint):
     def get(self, rule, status_code=200):
         return self._mroute('GET', rule, status_code)
 
@@ -53,33 +53,36 @@ class Rest(f.Blueprint):
 
             def handler(**kwargs):
                 # extract response content type
-                resp_type = f.request.accept_mimetypes
+                resp_type = flask.request.accept_mimetypes
                 type_suffix = kwargs.pop('resp_type', None)
                 if type_suffix:
                     suffix_mime = mimetypes.guess_type("res." + type_suffix)[0]
                     if suffix_mime:
-                        resp_type = MIMEAccept([(suffix_mime, 1)])
-                f.request.resp_type = resp_type
+                        resp_type = datastructures.MIMEAccept(
+                            [(suffix_mime, 1)])
+                flask.request.resp_type = resp_type
 
                 # update status code
                 if status:
-                    f.request.status_code = status
+                    flask.request.status_code = status
 
                 kwargs.pop("tenant_id")
 
-                context = Context(f.request.headers['X-User-Id'],
-                                  f.request.headers['X-Tenant-Id'],
-                                  f.request.headers['X-Auth-Token'],
-                                  f.request.headers)
-                set_ctx(context)
+                ctx = context.Context(
+                    flask.request.headers['X-User-Id'],
+                    flask.request.headers['X-Tenant-Id'],
+                    flask.request.headers[
+                        'X-Auth-Token'],
+                    flask.request.headers)
+                context.set_ctx(ctx)
 
                 # set func implicit args
                 args = inspect.getargspec(func).args
 
                 if 'ctx' in args:
-                    kwargs['ctx'] = context
+                    kwargs['ctx'] = ctx
 
-                if f.request.method in ['POST', 'PUT'] and 'data' in args:
+                if flask.request.method in ['POST', 'PUT'] and 'data' in args:
                     kwargs['data'] = request_data()
 
                 return func(**kwargs)
@@ -97,8 +100,8 @@ class Rest(f.Blueprint):
         return decorator
 
 
-RT_JSON = MIMEAccept([("application/json", 1)])
-RT_XML = MIMEAccept([("application/xml", 1)])
+RT_JSON = datastructures.MIMEAccept([("application/json", 1)])
+RT_XML = datastructures.MIMEAccept([("application/xml", 1)])
 
 
 def _clean_nones(obj):
@@ -136,14 +139,14 @@ def render(res=None, resp_type=None, status=None, **kwargs):
 
     res = _clean_nones(res)
 
-    status_code = getattr(f.request, 'status_code', None)
+    status_code = getattr(flask.request, 'status_code', None)
     if status:
         status_code = status
     if not status_code:
         status_code = 200
 
     if not resp_type:
-        resp_type = getattr(f.request, 'resp_type', RT_JSON)
+        resp_type = getattr(flask.request, 'resp_type', RT_JSON)
 
     if not resp_type:
         resp_type = RT_JSON
@@ -161,19 +164,20 @@ def render(res=None, resp_type=None, status=None, **kwargs):
     body = serializer.serialize(res)
     resp_type = str(resp_type)
 
-    return f.Response(response=body, status=status_code, mimetype=resp_type)
+    return flask.Response(response=body, status=status_code,
+                          mimetype=resp_type)
 
 
 def request_data():
-    if hasattr(f.request, 'parsed_data'):
-        return f.request.parsed_data
+    if hasattr(flask.request, 'parsed_data'):
+        return flask.request.parsed_data
 
-    if not f.request.content_length > 0:
+    if not flask.request.content_length > 0:
         LOG.debug("Empty body provided in request")
         return dict()
 
     deserializer = None
-    content_type = f.request.mimetype
+    content_type = flask.request.mimetype
     if not content_type or content_type in RT_JSON:
         deserializer = wsgi.JSONDeserializer()
     elif content_type in RT_XML:
@@ -183,9 +187,10 @@ def request_data():
         abort_and_log(400, "Content type '%s' isn't supported" % content_type)
 
     # parsed request data to avoid unwanted re-parsings
-    f.request.parsed_data = deserializer.deserialize(f.request.data)['body']
+    parsed_data = deserializer.deserialize(flask.request.data)['body']
+    flask.request.parsed_data = parsed_data
 
-    return f.request.parsed_data
+    return flask.request.parsed_data
 
 
 def abort_and_log(status_code, descr, exc=None):
@@ -195,7 +200,7 @@ def abort_and_log(status_code, descr, exc=None):
     if exc is not None:
         LOG.error(traceback.format_exc())
 
-    f.abort(status_code, description=descr)
+    flask.abort(status_code, description=descr)
 
 
 def render_error_message(error_code, error_message, error_name):
diff --git a/savanna/utils/crypto.py b/savanna/utils/crypto.py
index 0bf2db9d..370ce166 100644
--- a/savanna/utils/crypto.py
+++ b/savanna/utils/crypto.py
@@ -16,7 +16,7 @@
 from Crypto.PublicKey import RSA
 from Crypto import Random
 import paramiko
-from six import StringIO
+import six
 
 
 def generate_private_key(length=2048):
@@ -27,7 +27,7 @@ def generate_private_key(length=2048):
 
 def to_paramiko_private_key(pkey):
     """Convert private key (str) to paramiko-specific RSAKey object."""
-    return paramiko.RSAKey(file_obj=StringIO(pkey))
+    return paramiko.RSAKey(file_obj=six.StringIO(pkey))
 
 
 def private_key_to_public_key(key):
diff --git a/savanna/utils/openstack/images.py b/savanna/utils/openstack/images.py
index e4d04bf2..5f30c6fe 100644
--- a/savanna/utils/openstack/images.py
+++ b/savanna/utils/openstack/images.py
@@ -13,8 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from novaclient.v1_1.images import Image
-from novaclient.v1_1.images import ImageManager
+from novaclient.v1_1 import images
 
 
 PROP_DESCR = '_savanna_description'
@@ -32,7 +31,7 @@ def _ensure_tags(tags):
     return [tags] if type(tags) in [str, unicode] else tags
 
 
-class SavannaImage(Image):
+class SavannaImage(images.Image):
     def __init__(self, manager, info, loaded=False):
         info['description'] = info.get('metadata', {}).get(PROP_DESCR)
         info['username'] = info.get('metadata', {}).get(PROP_USERNAME)
@@ -60,7 +59,7 @@ class SavannaImage(Image):
         return self._info.copy()
 
 
-class SavannaImageManager(ImageManager):
+class SavannaImageManager(images.ImageManager):
     """Manage :class:`SavannaImage` resources.
 
     This is an extended version of nova client's ImageManager with support of
diff --git a/savanna/utils/openstack/keypairs.py b/savanna/utils/openstack/keypairs.py
index 22a0a844..6f4804ae 100644
--- a/savanna/utils/openstack/keypairs.py
+++ b/savanna/utils/openstack/keypairs.py
@@ -14,10 +14,10 @@
 # limitations under the License.
 
 from novaclient import base
-from novaclient.v1_1.keypairs import KeypairManager
+from novaclient.v1_1 import keypairs
 
 
-class SavannaKeypairManager(KeypairManager):
+class SavannaKeypairManager(keypairs.KeypairManager):
     def get(self, keypair):
         """Get a keypair.
 
diff --git a/savanna/utils/openstack/nova.py b/savanna/utils/openstack/nova.py
index fad4f289..163fc07e 100644
--- a/savanna/utils/openstack/nova.py
+++ b/savanna/utils/openstack/nova.py
@@ -16,15 +16,15 @@
 import logging
 
 from novaclient.v1_1 import client as nova_client
-from savanna.context import ctx
 
+from savanna import context
 import savanna.utils.openstack.base as base
-from savanna.utils.openstack.images import SavannaImageManager
-from savanna.utils.openstack.keypairs import SavannaKeypairManager
+from savanna.utils.openstack import images
+from savanna.utils.openstack import keypairs
 
 
-def novaclient():
-    headers = ctx().headers
+def client():
+    headers = context.current().headers
     username = headers['X-User-Name']
     token = headers['X-Auth-Token']
     tenant = headers['X-Tenant-Id']
@@ -39,25 +39,25 @@ def novaclient():
 
     nova.client.auth_token = token
     nova.client.management_url = compute_url
-    nova.images = SavannaImageManager(nova)
+    nova.images = images.SavannaImageManager(nova)
     if not hasattr(nova.keypairs, 'get'):
-        nova.keypairs = SavannaKeypairManager(nova)
+        nova.keypairs = keypairs.SavannaKeypairManager(nova)
 
     return nova
 
 
 def get_flavors():
-    return [flavor.name for flavor in novaclient().flavors.list()]
+    return [flavor.name for flavor in client().flavors.list()]
 
 
 def get_flavor(**kwargs):
-    return novaclient().flavors.find(**kwargs)
+    return client().flavors.find(**kwargs)
 
 
 def get_images():
-    return [image.id for image in novaclient().images.list()]
+    return [image.id for image in client().images.list()]
 
 
 def get_limits():
-    limits = novaclient().limits.get().absolute
+    limits = client().limits.get().absolute
     return dict((l.name, l.value) for l in limits)
diff --git a/savanna/utils/remote.py b/savanna/utils/remote.py
index 5190904b..5b989a05 100644
--- a/savanna/utils/remote.py
+++ b/savanna/utils/remote.py
@@ -15,13 +15,13 @@
 
 import paramiko
 
-from savanna.utils.crypto import to_paramiko_private_key
+from savanna.utils import crypto
 
 
 def setup_ssh_connection(host, username, private_key):
     """Setup SSH connection to the host using username and private key."""
     if type(private_key) in [str, unicode]:
-        private_key = to_paramiko_private_key(private_key)
+        private_key = crypto.to_paramiko_private_key(private_key)
     ssh = paramiko.SSHClient()
     ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
     ssh.connect(host, username=username, pkey=private_key)
diff --git a/savanna/utils/sqlatypes.py b/savanna/utils/sqlatypes.py
index 2cb66876..c0c60622 100644
--- a/savanna/utils/sqlatypes.py
+++ b/savanna/utils/sqlatypes.py
@@ -13,16 +13,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from sqlalchemy.ext.mutable import Mutable
-from sqlalchemy.types import TypeDecorator, VARCHAR
+from sqlalchemy.ext import mutable
+from sqlalchemy import types as st
 
 from savanna.openstack.common import jsonutils
 
 
-class JSONEncoded(TypeDecorator):
+class JSONEncoded(st.TypeDecorator):
     """Represents an immutable structure as a json-encoded string."""
 
-    impl = VARCHAR
+    impl = st.VARCHAR
 
     def process_bind_param(self, value, dialect):
         if value is not None:
@@ -36,7 +36,7 @@ class JSONEncoded(TypeDecorator):
 
 
 # todo verify this implementation
-class MutableDict(Mutable, dict):
+class MutableDict(mutable.Mutable, dict):
     @classmethod
     def coerce(cls, key, value):
         """Convert plain dictionaries to MutableDict."""
@@ -45,7 +45,7 @@ class MutableDict(Mutable, dict):
                 return MutableDict(value)
 
             # this call will raise ValueError
-            return Mutable.coerce(key, value)
+            return mutable.Mutable.coerce(key, value)
         else:
             return value
 
@@ -66,7 +66,7 @@ class MutableDict(Mutable, dict):
 
 
 # todo verify this implementation
-class MutableList(Mutable, list):
+class MutableList(mutable.Mutable, list):
     @classmethod
     def coerce(cls, key, value):
         """Convert plain lists to MutableList."""
@@ -75,7 +75,7 @@ class MutableList(Mutable, list):
                 return MutableList(value)
 
             # this call will raise ValueError
-            return Mutable.coerce(key, value)
+            return mutable.Mutable.coerce(key, value)
         else:
             return value
 
diff --git a/tox.ini b/tox.ini
index a2ffedc0..9e5eb515 100644
--- a/tox.ini
+++ b/tox.ini
@@ -45,8 +45,6 @@ commands =
     pylint --output-format=parseable --rcfile=.pylintrc bin/savanna-api bin/savanna-manage savanna | tee pylint-report.txt
 
 [flake8]
-# H302 import only modules
-ignore = H302
 show-source = true
 builtins = _
 exclude=.venv,.git,.tox,dist,doc,*openstack/common*,*lib/python*,*egg,tools