diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
new file mode 100644
index 0000000..880bfe1
--- /dev/null
+++ b/.github/workflows/tests.yaml
@@ -0,0 +1,38 @@
+  # This workflow will install Python dependencies, run tests and lint with a variety of Python versions
+# For more information see: https://help.github.com/actions/language-and-framework-guides/using-python-with-github-actions
+
+name: Functional Tests
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+env:
+  VIRTUALENV_PIP: "20.2.3"
+
+jobs:
+  build:
+
+    #runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
+    strategy:
+      fail-fast: false
+      matrix:
+        python: [3.8.14]
+        tox-env: [pep8, functional]
+    env:
+      TOXENV: ${{ matrix.tox-env }}
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python }}
+      - name: Install Tox and any other packages
+        run: |
+          pip install tox
+      - name: Running Tox
+        run: tox
+
diff --git a/rate_limit/__init__.py b/rate_limit/__init__.py
index 8eed2dc..c0998a4 100644
--- a/rate_limit/__init__.py
+++ b/rate_limit/__init__.py
@@ -12,7 +12,7 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
-from .rate_limit import OpenStackRateLimitMiddleware
+from .ratelimit import OpenStackRateLimitMiddleware
 
 
 def main(global_config, **settings):
diff --git a/rate_limit/common.py b/rate_limit/common.py
index 2ba5eaf..35d863f 100644
--- a/rate_limit/common.py
+++ b/rate_limit/common.py
@@ -33,9 +33,8 @@
 
 
 class Constants(object):
-    """
-    Common constants used in various places.
-    """
+    """Common constants used in various places."""
+
     ratelimit_response = 'ratelimit_response'
     blacklist_response = 'blacklist_response'
     max_sleep_time_seconds = 'max_sleep_time_seconds'
diff --git a/rate_limit/log.py b/rate_limit/log.py
index 7fa288b..c5ecb78 100644
--- a/rate_limit/log.py
+++ b/rate_limit/log.py
@@ -21,10 +21,8 @@
 
 
 class Logger(object):
-    """
-    Logger that attempts to log and ignores any error.
+    """Logger that attempts to log and ignores any error."""
 
-    """
     def __init__(self, name, product_name='rate_limit'):
         self.__logger = logging.getLogger(name)
         try:
diff --git a/rate_limit/provider.py b/rate_limit/provider.py
index 46e9d2c..e7f499b 100644
--- a/rate_limit/provider.py
+++ b/rate_limit/provider.py
@@ -120,7 +120,6 @@ def _get_wildcard_ratelimits(self, ratelimits, target_type_uri):
         :param target_type_uri: the target type URI of the request
         :return: target type uri ratelimits if exists
         """
-
         ttu_ratelimits = []
         pattern_list = [
             lr_key for lr_key in ratelimits
@@ -134,14 +133,13 @@ def _get_wildcard_ratelimits(self, ratelimits, target_type_uri):
 
     def _match(self, uri, pattern_list):
         """
-        Check if a URI matches to one of the patterns
+        Check if a URI matches to one of the patterns.
 
         :param uri: URI to check if it matches to one of the patterns
         :param pattern_list : patterns to match against the URI
         :return: True if path matches a pattern of the list and
                  pattern as key for self.local_ratelimits.
         """
-
         for pattern in pattern_list:
             if uri.startswith(pattern[:-1]):
                 return True, pattern
diff --git a/rate_limit/rate_limit.py b/rate_limit/ratelimit.py
similarity index 98%
rename from rate_limit/rate_limit.py
rename to rate_limit/ratelimit.py
index 8d057a6..1cbf7df 100644
--- a/rate_limit/rate_limit.py
+++ b/rate_limit/ratelimit.py
@@ -16,13 +16,13 @@
 
 from datadog.dogstatsd import DogStatsd
 
-from . import backend as rate_limit_backend
-from . import common
-from . import errors
-from . import provider
-from . import response
-from . import units
-from . import log
+from rate_limit import backend as rate_limit_backend
+from rate_limit import common
+from rate_limit import errors
+from rate_limit import provider
+from rate_limit import response
+from rate_limit import units
+from rate_limit import log
 
 
 class OpenStackRateLimitMiddleware(object):
@@ -146,7 +146,7 @@ def __init__(self, app, **conf):
         self.logger.info("OpenStack Rate Limit Middleware ready for requests.")
 
     def _setup_response(self):
-        """Setup configurable RateLimitExceededResponse and BlacklistResponse."""
+        """Set up configurable RateLimitExceededResponse and BlacklistResponse."""
         # Default responses.
         ratelimit_response = response.RateLimitExceededResponse()
         blacklist_response = response.BlacklistResponse()
@@ -185,7 +185,7 @@ def _setup_response(self):
             self.blacklist_response = blacklist_response
 
     def __setup_limes_ratelimit_provider(self):
-        """Setup Limes as provider for rate limits. If not successful fallback to configuration file."""
+        """Set up Limes as provider for rate limits. If not successful fallback to configuration file."""
         try:
             limes_ratelimit_provider = provider.LimesRateLimitProvider(
                 service_type=self.service_type,
diff --git a/rate_limit/tests/fake.py b/rate_limit/tests/fake.py
index 4ec5370..ac92dc5 100644
--- a/rate_limit/tests/fake.py
+++ b/rate_limit/tests/fake.py
@@ -36,7 +36,7 @@ def incr(self, key, delta=1, time=0):
     def decr(self, key, delta=1, time=0):
         return self.incr(key, delta=-delta, time=time)
 
-    def delete(self,key):
+    def delete(self, key):
         try:
             del self.store[key]
         except KeyError:
diff --git a/rate_limit/tests/test_actiongroups.py b/rate_limit/tests/test_actiongroups.py
index 0b1d788..a4fa90c 100644
--- a/rate_limit/tests/test_actiongroups.py
+++ b/rate_limit/tests/test_actiongroups.py
@@ -15,7 +15,7 @@
 import unittest
 import os
 
-from rate_limit.rate_limit import OpenStackRateLimitMiddleware
+from rate_limit.ratelimit import OpenStackRateLimitMiddleware
 from . import fake
 
 
@@ -42,19 +42,18 @@ def test_groups(self):
         self.assertIsNotNone(
             rl_groups,
             "expected rate limit groups to be '{0}' but got '{1}'".format(
-"""
-groups:
-  write:
-    - update
-    - delete
-    - update/*
-    - delete/os-*
-
-  read:
-    - read
-    - read/list
-    - read/*/list
-""",
+                """
+                groups:
+                  write:
+                    - update
+                    - delete
+                    - update/*
+                    - delete/os-*
+                  read:
+                    - read
+                    - read/list
+                    - read/*/list
+                """,
                 rl_groups
             )
         )
@@ -95,7 +94,7 @@ def test_mapping(self):
             },
             {
                 'action': 'read/rules/list',
-                'expected':'read/rules/list', 
+                'expected': 'read/rules/list',
             },
         ]
 
diff --git a/rate_limit/tests/test_limesratelimitprovider.py b/rate_limit/tests/test_limesratelimitprovider.py
index 4d9abb1..52cfd1a 100644
--- a/rate_limit/tests/test_limesratelimitprovider.py
+++ b/rate_limit/tests/test_limesratelimitprovider.py
@@ -2,7 +2,7 @@
 import os
 import json
 
-from rate_limit.rate_limit import OpenStackRateLimitMiddleware, provider
+from rate_limit import OpenStackRateLimitMiddleware, provider
 from . import fake
 
 WORKDIR = os.path.dirname(os.path.realpath(__file__))
diff --git a/rate_limit/tests/test_middleware.py b/rate_limit/tests/test_middleware.py
index 09c33f6..af84dfa 100644
--- a/rate_limit/tests/test_middleware.py
+++ b/rate_limit/tests/test_middleware.py
@@ -13,10 +13,11 @@
 # under the License.
 
 import os
-import time
 import unittest
 
-from rate_limit.rate_limit import OpenStackRateLimitMiddleware
+from unittest.mock import patch, DEFAULT
+
+from rate_limit.ratelimit import OpenStackRateLimitMiddleware
 from rate_limit.response import BlacklistResponse
 from rate_limit.response import RateLimitExceededResponse
 from . import fake
@@ -138,102 +139,94 @@ def test_get_rate_limit(self):
                 "rate limit for '{0} {1}' should be '{2}' but got '{3}'".format(action, target_type_uri, expected_ratelimit, rate_limit)
             )
 
-    def test_is_ratelimited_swift_local_container_update(self):
+    @patch.multiple('pyredis.Pool', evalsha=DEFAULT, script_exists=DEFAULT)
+    def test_is_ratelimited_swift_local_container_update(self, evalsha, script_exists):
         scope = '123456'
         action = 'update'
         target_type_uri = 'account/container'
 
+        retry_after = 58
+        remaining = 0
+
+        script_exists.return_value = ['True']
+        evalsha.return_value = [remaining, retry_after]
+
         # The current configuration as per /fixtures/swift.yaml allows 2r/m for target type URI account/container and action update.
         # Thus the first 2 requests should not be rate limited but the 3rd one.
-        expected = [
-            # 1st requests not rate limited.
-            None,
-            # 2nd request also not rate limited.
-            None,
-            # 3rd request should be a rate limit response
-            RateLimitExceededResponse(
-                status='498 Rate Limited',
-                body='Rate Limit Exceeded',
-                headerlist=[('X-Retry-After', 58), ('X-RateLimit-Retry-After', 58),
-                                        ('X-RateLimit-Limit', '2r/m'), ('X-RateLimit-Remaining', 0)]
-            )
-        ]
+        expected = RateLimitExceededResponse(
+            status='498 Rate Limited',
+            body='Rate Limit Exceeded',
+            headerlist=[('X-Retry-After', 58),
+                        ('X-RateLimit-Retry-After', retry_after),
+                        ('X-RateLimit-Limit', '2r/m'),
+                        ('X-RateLimit-Remaining', remaining)]
+        )
 
-        for i in range(len(expected)):
-            result = self.app._rate_limit(scope=scope, action=action, target_type_uri=target_type_uri)
-            time.sleep(1)
-            is_equal, msg = response_equal(expected[i], result)
-            self.assertTrue(is_equal, "test #{0} failed: {1}".format(i, msg))
+        result = self.app._rate_limit(scope=scope, action=action, target_type_uri=target_type_uri)
+        is_equal, msg = response_equal(expected, result)
+        self.assertTrue(is_equal, "test failed: {0}".format(msg))
 
-    def test_is_ratelimited_swift_local_wildcard_update(self):
+    @patch.multiple('pyredis.Pool', evalsha=DEFAULT, script_exists=DEFAULT)
+    def test_is_ratelimited_swift_local_wildcard_update(self, evalsha, script_exists):
         scope = '123456'
         action = 'update'
         target_type_uri = 'account/container/foo_object'
 
+        retry_after = 58
+        remaining = 0
+
+        script_exists.return_value = ['True']
+        evalsha.return_value = [remaining, retry_after]
+
         # The current configuration as per /fixtures/swift.yaml allows 2r/m
         # for target type URI account/container and action update
         # which is targeted by wildcard pattern account/*
         # Thus the first 2 requests should not be rate limited but the 3rd one.
-        expected = [
-            # 1st requests not rate limited.
-            None,
-            # 2nd request also not rate limited.
-            None,
-            # 3rd request should be a rate limit response
-            RateLimitExceededResponse(
-                status='498 Rate Limited',
-                body='Rate Limit Exceeded',
-                headerlist=[
-                    ('X-Retry-After', 58),
-                    ('X-RateLimit-Retry-After', 58),
-                    ('X-RateLimit-Limit', '2r/m'),
-                    ('X-RateLimit-Remaining', 0),
-                ]
-            )
-        ]
+        expected = RateLimitExceededResponse(
+            status='498 Rate Limited',
+            body='Rate Limit Exceeded',
+            headerlist=[
+                ('X-Retry-After', retry_after),
+                ('X-RateLimit-Retry-After', retry_after),
+                ('X-RateLimit-Limit', '2r/m'),
+                ('X-RateLimit-Remaining', remaining),
+            ]
+        )
 
-        for i in range(len(expected)):
-            result = self.app._rate_limit(scope=scope, action=action, target_type_uri=target_type_uri)
-            time.sleep(1)
-            is_equal, msg = response_equal(expected[i], result)
-            self.assertTrue(is_equal, "test #{0} failed: {1}".format(i, msg))
+        result = self.app._rate_limit(scope=scope, action=action, target_type_uri=target_type_uri)
+        is_equal, msg = response_equal(expected, result)
+        self.assertTrue(is_equal, "test failed: {0}".format(msg))
 
-    def test_is_ratelimited_swift_local_after_wildcard_update(self):
+    @patch.multiple('pyredis.Pool', evalsha=DEFAULT, script_exists=DEFAULT)
+    def test_is_ratelimited_swift_local_after_wildcard_update(self, evalsha, script_exists):
         scope = '123456'
         action = 'update'
         target_type_uri = 'account/container/foo_object/something/else'
 
+        retry_after = 58
+        remaining = 0
+
+        script_exists.return_value = ['True']
+        evalsha.return_value = [remaining, retry_after]
+
         # The current configuration as per /fixtures/swift.yaml allows 4r/m
         # for target type URI account/container/foo_object/something/else
         # and action update which is goes after wildcard pattern account/*
         # Thus the first 4 requests should not be rate limited but the 5rd one.
-        expected = [
-            # 1st requests not rate limited.
-            None,
-            # 2nd request also not rate limited.
-            None,
-            # 3rd request also not rate limited.
-            None,
-            # 4th request also not rate limited.
-            None,
-            # 5th request should be a rate limit response
-            RateLimitExceededResponse(
-                status='498 Rate Limited',
-                body='Rate Limit Exceeded',
-                headerlist=[
-                    ('X-Retry-After', 58),
-                    ('X-RateLimit-Retry-After', 58),
-                    ('X-RateLimit-Limit', '2r/m'),
-                    ('X-RateLimit-Remaining', 0),
-                ]
-            )
-        ]
+        expected = RateLimitExceededResponse(
+            status='498 Rate Limited',
+            body='Rate Limit Exceeded',
+            headerlist=[
+                ('X-Retry-After', 58),
+                ('X-RateLimit-Retry-After', retry_after),
+                ('X-RateLimit-Limit', '4r/m'),
+                ('X-RateLimit-Remaining', remaining),
+            ]
+        )
 
-        for i in range(len(expected)):
-            result = self.app._rate_limit(scope=scope, action=action, target_type_uri=target_type_uri)
-            time.sleep(1)
-            is_equal, msg = response_equal(expected[i], result)
-            self.assertTrue(is_equal, "test #{0} failed: {1}".format(i, msg))
+        result = self.app._rate_limit(scope=scope, action=action, target_type_uri=target_type_uri)
+        is_equal, msg = response_equal(expected, result)
+        self.assertTrue(is_equal, "test failed: {0}".format(msg))
 
 
 def response_equal(expected, got):
@@ -248,14 +241,14 @@ def response_equal(expected, got):
             return False, "expected status '{0}' but got '{1}'".format(expected.status, got.status)
 
         if expected.has_body and expected.body != got.body:
-                return False, "expected body '{0}' but got '{1}'".format(expected.body, got.body)
+            return False, "expected body '{0}' but got '{1}'".format(expected.body, got.body)
 
         if not expected.has_body and expected.json_body != got.json_body:
-                return False, "expected json body '{0}' but got '{1}'".format(expected.json_body, got.json_body)
+            return False, "expected json body '{0}' but got '{1}'".format(expected.json_body, got.json_body)
 
         return True, "items are equal"
 
-    if type(expected) != type(got):
+    if type(expected) is not type(got):
         return False, "expected type {0} but got type {1}".format(type(expected), type(got))
 
     # Compare arguments if neither RateLimitResponse nor BlacklistResponse.
diff --git a/rate_limit/tests/test_parse_config.py b/rate_limit/tests/test_parse_config.py
index 0fa5a41..e7d9e1a 100644
--- a/rate_limit/tests/test_parse_config.py
+++ b/rate_limit/tests/test_parse_config.py
@@ -72,16 +72,16 @@ def test_load_swift_config(self):
     def test_parse_and_convert_to_per_seconds(self):
         stimuli = [
             {
-                'in':  '5r/s',
+                'in': '5r/s',
                 'expected': 5
             },
             {
                 'in': '1r/m',
-                'expected': round(1/60.0, 4)
+                'expected': round(1 / 60.0, 4)
             },
             {
                 'in': '10r/d',
-                'expected': round(1/8640.0,4)
+                'expected': round(1 / 8640.0, 4)
             },
             {
                 'in': '0.5r/s',
diff --git a/rate_limit/tests/test_response.py b/rate_limit/tests/test_response.py
index 86d4a4a..f31b2ba 100644
--- a/rate_limit/tests/test_response.py
+++ b/rate_limit/tests/test_response.py
@@ -1,6 +1,5 @@
 import json
 import os
-import six
 import unittest
 
 
@@ -23,7 +22,8 @@ def test_default_ratelimitexceededresponse_json(self):
         self.assertEqual(
             ratelimit_response.content_type,
             common.Constants.content_type_json,
-            "expected response content type to be equal. want '{0}' but got '{1}'".format(common.Constants.content_type_json, ratelimit_response.content_type)
+            "expected response content type to be equal. want '{0}' but got '{1}'".format(
+                common.Constants.content_type_json, ratelimit_response.content_type)
         )
 
         actual_body = sorted(json.loads(ratelimit_response.json_body))
@@ -39,7 +39,8 @@ def test_default_ratelimitexceededresponse_json(self):
 
     def test_custom_ratelimitexceededresponse_html(self):
         conf = common.load_config(SWIFTCONFIGPATH)
-        status, status_code, headers, body, json_body = response.response_parameters_from_config(conf.get(common.Constants.ratelimit_response))
+        status, status_code, headers, body, json_body = response.response_parameters_from_config(
+            conf.get(common.Constants.ratelimit_response))
 
         ratelimit_response = response.RateLimitExceededResponse(
             status=status,
@@ -105,16 +106,19 @@ def test_default_blacklistresponse(self):
             .format(common.Constants.content_type_json, blacklist_response.content_type)
         )
 
-        expected_json_body = json.dumps({"error": {"status": "497 Blacklisted", "message": "You have been blacklisted"}}, sort_keys=True)
+        expected_json_body = json.dumps(
+            {"error": {"status": "497 Blacklisted", "message": "You have been blacklisted"}}, sort_keys=True)
         self.assertEqual(
             blacklist_response.json_body,
             expected_json_body,
-            "expected blacklist response body to be '{0}' but got '{1}'".format(expected_json_body, blacklist_response.json_body)
+            "expected blacklist response body to be '{0}' but got '{1}'".format(expected_json_body,
+                                                                                blacklist_response.json_body)
         )
 
     def test_custom_blacklistresponse_json(self):
         conf = common.load_config(SWIFTCONFIGPATH)
-        status, status_code, headers, body, json_body = response.response_parameters_from_config(conf.get(common.Constants.blacklist_response))
+        status, status_code, headers, body, json_body = response.response_parameters_from_config(
+            conf.get(common.Constants.blacklist_response))
 
         blacklist_response = response.BlacklistResponse(
             status=status,
@@ -144,7 +148,11 @@ def test_custom_blacklistresponse_json(self):
             .format(common.Constants.content_type_json, blacklist_response.content_type)
         )
 
-        expected_json_body = json.dumps({"error": {"status": "497 Blacklisted", "message": "You have been blacklisted. Please contact and administrator."}}, sort_keys=True)
+        expected_json_body = json.dumps(
+            {"error": {"status": "497 Blacklisted",
+                       "message": "You have been blacklisted. Please contact and administrator."}},
+            sort_keys=True)
+
         self.assertEqual(
             blacklist_response.json_body,
             expected_json_body,
diff --git a/rate_limit/tests/test_units.py b/rate_limit/tests/test_units.py
index 06a9b88..7067cfe 100644
--- a/rate_limit/tests/test_units.py
+++ b/rate_limit/tests/test_units.py
@@ -35,7 +35,7 @@ def test_parse_sliding_window_rate_limit(self):
             },
             {
                 'input': '100r/d',
-                'expected': (100.0, 24*3600.0)
+                'expected': (100.0, 24 * 3600.0)
             },
             {
                 'input': '5r/2m',
diff --git a/rate_limit/utils.py b/rate_limit/utils.py
index c231af2..76f62db 100644
--- a/rate_limit/utils.py
+++ b/rate_limit/utils.py
@@ -11,7 +11,7 @@ def str_if_bytes(value):
 # NOTE: This function was copied from
 # https://github.com/andymccurdy/redis-py/blob/master/redis/client.py#L114
 def parse_info(response):
-    "Parse the result of Redis's INFO command into a Python dict"
+    """Parse the result of Redis's INFO command into a Python dict."""
     info = {}
     response = str_if_bytes(response)
 
diff --git a/test-requirements.txt b/test-requirements.txt
index df4b868..d608750 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -1,4 +1,4 @@
-flake8-docstrings==0.2.1.post1 # MIT
+flake8-docstrings==1.7.0 # MIT
 
 fixtures>=3.0.0 # Apache-2.0/BSD
 mock>=2.0.0 # BSD
@@ -8,3 +8,4 @@ testrepository>=0.0.18 # Apache-2.0/BSD
 testtools>=1.4.0 # MIT
 os-testr>=0.8.0 # Apache-2.0
 WebTest>=2.0 # MIT
+stestr>=1.0.0 # Apache-2.0
diff --git a/tox.ini b/tox.ini
index 7b63590..facac6f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,11 +2,14 @@
 minversion = 2.0
 # avoid sdist
 skipsdist = True
-envlist = py35,py36,py37,pep8
+envlist = py37,py38,pep8
 
 [testenv]
 usedevelop = True
-install_command = {toxinidir}/tools/tox_install.sh {env:UPPER_CONSTRAINTS_FILE:https://raw.githubusercontent.com/sapcc/requirements/stable/rocky-m3/upper-constraints.txt} {opts} {packages}
+deps =
+    -c{env:TOX_CONSTRAINTS_FILE:https://raw.githubusercontent.com/sapcc/requirements/stable/zed-m3/upper-constraints.txt}
+    -r{toxinidir}/requirements.txt
+    -r{toxinidir}/test-requirements.txt
 setenv = VIRTUAL_ENV={envdir}
          BRANCH_NAME=master
          CLIENT_NAME=rate-limit
@@ -15,20 +18,25 @@ setenv = VIRTUAL_ENV={envdir}
          OS_TEST_TIMEOUT=60
          TESTS_DIR=./rate_limit/tests/
 
-deps = -r{toxinidir}/requirements.txt
-       -r{toxinidir}/test-requirements.txt
+[testenv:functional]
+setenv =
+  {[testenv]setenv}
+  OS_TEST_PATH=./rate_limit/tests
 commands = stestr run {posargs}
 
 [testenv:pep8]
+allowlist_externals = flake8
+deps =
+  {[testenv]deps}
 commands = flake8
 
 [testenv:venv]
 commands = {posargs}
 
 [flake8]
-ignore = D100,D101,D102,D103,D104,D203,D205,W605
+ignore = D100,D101,D102,D103,D104,D107,D203,D205,W605
 show-source = True
-exclude = .venv,.tox,dist,doc,*egg,build,test*
+exclude = .git,__pycache__,docs/source/conf.py,old,build,dist,*.egg,.tox,venv,.venv
 max-line-length = 140
 
 [testenv:docs]