diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 47b51fadf3f5944a6669f808ccec0a3dff4977a1..287ad22bd2f3ad5291ecaab7746d5d84193adbd9 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,12 +1,20 @@
 image: $CI_REGISTRY_IMAGE/env:latest
 
 stages:
+ - check
  - build
  - test
  - report
  - deploy
 
-front-end:
+python:
+  stage: check
+  before_script:
+    - ./manage.sh update_dev_packages
+  script:
+    - ./manage.sh pep8_check
+
+build:web:
   stage: build
   before_script:
     - ./manage.sh npm_packages
@@ -16,14 +24,18 @@ front-end:
     - ./manage.sh styles
     - ./manage.sh grunt_build
 
-coding-rules:
+build:docker:
   stage: build
   before_script:
-    - ./manage.sh update_dev_packages
+    - docker login -u gitlab-ci-token -p $CI_JOB_TOKEN $CI_REGISTRY
   script:
-    - ./manage.sh pep8_check
+    - docker build -t $CI_REGISTRY_IMAGE:${CI_COMMIT_TAG:-latest} .
+    - docker push $CI_REGISTRY_IMAGE:${CI_COMMIT_TAG:-latest}
+  only:
+    - master
+    - tags
 
-unit-test:
+test:unit:
   stage: test
   before_script:
     - ./manage.sh update_dev_packages
@@ -34,7 +46,7 @@ unit-test:
       - coverage
     expire_in: 1 hour
 
-functional-test:
+test:functional:
   stage: test
   image: docker:stable
   services:
@@ -57,11 +69,11 @@ coverage:
   script:
     - ./manage.sh coverage
   dependencies:
-    - unit-test
-    - functional-test
+    - test:unit
+    - test:functional
   coverage: '/TOTAL.*\s+(\d+%)$/'
 
-deploy-test:
+deploy:test:
   image: docker:stable
   stage: deploy
   only:
diff --git a/Dockerfile b/Dockerfile
index 70fb0323bb14b67f157d02f6017bc08a6cefaf23..40ac3eb320098673275e7ee864731e7f8cd8090d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -4,9 +4,7 @@ RUN apk add \
  git \
  build-base \
  libxml2-dev \
- libxslt-dev \
- libffi-dev \
- openssl-dev
+ libxslt-dev
 
 # Only to use the docker cache and optimize the build time
 WORKDIR /src
@@ -24,7 +22,6 @@ LABEL description="A privacy-respecting, hackable metasearch engine."
 RUN apk add \
  ca-certificates \
  libxslt \
- openssl \
 && pip install coverage
 
 COPY --from=builder /install/ /usr/local/
diff --git a/manage.sh b/manage.sh
index 47da7b36e7b850dba5c655678340c74d61f5b353..1d21b5886557e9c0a316fc109901662978091d63 100755
--- a/manage.sh
+++ b/manage.sh
@@ -38,6 +38,7 @@ pep8_check() {
     #  W503 line break before binary operator
     #  E722 do not use bare 'except'
     pycodestyle --exclude=searx/static --max-line-length=120 --ignore "E402,W503,E722" "$SEARX_DIR" "$BASE_DIR/tests"
+    flake8 --ignore=E722 $SEARX_DIR/*.py
 }
 
 unit_tests() {
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 1de575509df51a7ab65090584ed94374bb422a9a..695f9e18333ea12f236aba72309063e2f51b121b 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -1,6 +1,7 @@
 babel==2.3.4
 mock==2.0.0
-pycodestyle==2.4.0
+pycodestyle==2.5.0
+flake8==3.7.7
 mockredispy==2.9.3
 pytest==4.1.0
 pytest-cov==2.6.1
diff --git a/requirements.txt b/requirements.txt
index fc7eac0050a89571a9fbc3abeba030fe65e126f8..ba135f738b3a6463b9b89de931c79b9b346bf15d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,11 +1,8 @@
-redis==3.2.1
-certifi==2017.11.5
 flask==1.0.2
 flask-babel==0.11.2
-lxml==4.2.3
-idna==2.7
-pygments==2.1.3
-pyopenssl==18.0.0
-python-dateutil==2.7.3
-pyyaml==3.13
-requests[socks]==2.19.1
+lxml==4.3.3
+pygments==2.3.1
+python-dateutil==2.8.0
+pyyaml==5.1
+requests[socks]==2.21.0
+redis==3.2.1
diff --git a/searx/__init__.py b/searx/__init__.py
index 7324c1e4b1eded5819d14659dc8f9a39bbc724b2..5bddf92189ecd0f1b7a2f70941ddda54408762b9 100644
--- a/searx/__init__.py
+++ b/searx/__init__.py
@@ -15,18 +15,11 @@ along with searx. If not, see < http://www.gnu.org/licenses/ >.
 (C) 2013- by Adam Tauber, <asciimoo@gmail.com>
 '''
 
-import certifi
 import logging
 from os import environ
 from os.path import realpath, dirname, join, abspath, isfile
-from io import open
-from ssl import OPENSSL_VERSION_INFO, OPENSSL_VERSION
-try:
-    from yaml import load
-except ImportError:
-    from sys import exit, stderr
-    stderr.write('[E] install pyyaml\n')
-    exit(2)
+
+import yaml
 
 searx_dir = abspath(dirname(__file__))
 engine_dir = dirname(realpath(__file__))
@@ -53,7 +46,11 @@ if not settings_path:
 
 # load settings
 with open(settings_path, 'r', encoding='utf-8') as settings_yaml:
-    settings = load(settings_yaml)
+    # XXX: docker-compose does not support yet yaml >= 5
+    if int(yaml.__version__.split('.')[0]) >= 5:
+        settings = yaml.load(settings_yaml, Loader=yaml.FullLoader)
+    else:
+        settings = yaml.load(settings_yaml)
 
 '''
 enable debug if
@@ -73,12 +70,6 @@ logging.basicConfig(level=getattr(logging, searx_loglevel))
 
 logger = logging.getLogger('searx')
 logger.debug('read configuration from %s', settings_path)
-# Workaround for openssl versions <1.0.2
-# https://github.com/certifi/python-certifi/issues/26
-if OPENSSL_VERSION_INFO[0:3] < (1, 0, 2):
-    if hasattr(certifi, 'old_where'):
-        environ['REQUESTS_CA_BUNDLE'] = certifi.old_where()
-    logger.warning('You are using an old openssl version({0}), please upgrade above 1.0.2!'.format(OPENSSL_VERSION))
 
 logger.info('Initialisation done')
 
diff --git a/searx/engines/__init__.py b/searx/engines/__init__.py
index f32b57202352f3ac9d3ac5df25080768a2c03452..953fa8bf0360fa19fc07ba459751d4663e707b39 100644
--- a/searx/engines/__init__.py
+++ b/searx/engines/__init__.py
@@ -18,12 +18,11 @@ along with searx. If not, see < http://www.gnu.org/licenses/ >.
 
 import sys
 import threading
-from os.path import realpath, dirname
-from io import open
+import json
+from pathlib import Path
 from babel.localedata import locale_identifiers
 from flask_babel import gettext
 from operator import itemgetter
-from json import loads
 from requests import get
 from searx import settings
 from searx import logger
@@ -32,13 +31,14 @@ from searx.utils import load_module, match_language
 
 logger = logger.getChild('engines')
 
-engine_dir = dirname(realpath(__file__))
+engine_dir = Path(__file__).parent
 
 engines = {}
 
 categories = {'general': []}
 
-languages = loads(open(engine_dir + '/../data/engines_languages.json', 'r', encoding='utf-8').read())
+with open(engine_dir.parent / "data" / "engines_languages.json", encoding='utf-8') as fd:
+    languages = json.load(fd)
 babel_langs = [lang_parts[0] + '-' + lang_parts[-1] if len(lang_parts) > 1 else lang_parts[0]
                for lang_parts in (lang_code.split('_') for lang_code in locale_identifiers())]
 
diff --git a/searx/engines/arxiv.py b/searx/engines/arxiv.py
index 5ef84f0c1df2e26146d42855054024714fae83a7..84e844fbbcd5e8fd5a277a9a5185ceb17444bd89 100644
--- a/searx/engines/arxiv.py
+++ b/searx/engines/arxiv.py
@@ -61,7 +61,7 @@ def response(resp):
             content = content_string.format(doi_content="", abstract_content=abstract)
 
         if len(content) > 300:
-                    content = content[0:300] + "..."
+            content = content[0:300] + "..."
         # TODO: center snippet on query term
 
         publishedDate = datetime.strptime(entry.xpath('.//published')[0].text, '%Y-%m-%dT%H:%M:%SZ')
diff --git a/searx/engines/currency_convert.py b/searx/engines/currency_convert.py
index 9424d7d5ece8ad60b6f262baf6b0485ce521a00a..2a2a3c35d80d60b8a9c28ab56a7f50529d4096c2 100644
--- a/searx/engines/currency_convert.py
+++ b/searx/engines/currency_convert.py
@@ -1,10 +1,9 @@
 import json
 import re
-import os
 import sys
 import unicodedata
 
-from io import open
+from pathlib import Path
 from datetime import datetime
 
 
@@ -88,10 +87,10 @@ def response(resp):
 def load():
     global db
 
-    current_dir = os.path.dirname(os.path.realpath(__file__))
-    json_data = open(current_dir + "/../data/currencies.json", 'r', encoding='utf-8').read()
-
-    db = json.loads(json_data)
+    with open(
+        Path(__file__).parent.parent / "data" / "currencies.json", encoding='utf-8'
+    ) as fd:
+        db = json.load(fd)
 
 
 load()
diff --git a/searx/engines/json_engine.py b/searx/engines/json_engine.py
index 550947ab6818587e15b77259f06c348c3f2baeca..7a48bc8cee536229822d9fc1ecf77a75912da2e2 100644
--- a/searx/engines/json_engine.py
+++ b/searx/engines/json_engine.py
@@ -1,4 +1,4 @@
-from collections import Iterable
+from collections.abc import Iterable
 from json import loads
 from searx.url_utils import urlencode
 from searx.utils import to_string
diff --git a/searx/engines/pubmed.py b/searx/engines/pubmed.py
index 055f092269d64adcfb5d3f004753bccbbaf8c176..82a37a564e7efca26fa1c50066215f467e40f506 100644
--- a/searx/engines/pubmed.py
+++ b/searx/engines/pubmed.py
@@ -81,7 +81,7 @@ def response(resp):
             pass
 
         if len(content) > 300:
-                    content = content[0:300] + "..."
+            content = content[0:300] + "..."
         # TODO: center snippet on query term
 
         res_dict = {'url': url,
diff --git a/searx/engines/wikidata.py b/searx/engines/wikidata.py
index 047f1ba77c0c82d52826b7370576f05ea5f4fd69..81cf262c50c5bd775f113fffa64e606f5d1100a6 100644
--- a/searx/engines/wikidata.py
+++ b/searx/engines/wikidata.py
@@ -374,7 +374,7 @@ def add_url(urls, result, property_id=None, default_label=None, url_prefix=None,
 
     # wiki links don't have property in wikidata page
     if link_type and 'wiki' in link_type:
-            links.append(get_wikilink(result, link_type))
+        links.append(get_wikilink(result, link_type))
     else:
         dom_element = result.xpath(property_xpath.replace('{propertyid}', property_id))
         if dom_element:
diff --git a/searx/query.py b/searx/query.py
index 89fe0607b584663034690725cb2f692fc2d55e3e..1dde7f329bd61653b395ac4fd1ca4690347214a6 100644
--- a/searx/query.py
+++ b/searx/query.py
@@ -22,7 +22,6 @@ from searx.engines import (
     categories, engines, engine_shortcuts
 )
 import re
-import sys
 
 
 VALID_LANGUAGE_CODE = re.compile(r'^[a-z]{2,3}(-[a-zA-Z]{2})?$')
@@ -78,20 +77,21 @@ class RawTextQuery(object):
 
                     # if correct language-code is found
                     # set it as new search-language
-                    if (lang == lang_id
-                        or lang == lang_name
-                        or lang == english_name
-                        or lang.replace('-', ' ') == country)\
-                       and lang not in self.languages:
-                            parse_next = True
-                            lang_parts = lang_id.split('-')
-                            if len(lang_parts) == 2:
-                                self.languages.append(lang_parts[0] + '-' + lang_parts[1].upper())
-                            else:
-                                self.languages.append(lang_id)
-                            # to ensure best match (first match is not necessarily the best one)
-                            if lang == lang_id:
-                                break
+                    if (
+                        lang in [lang_id, lang_name, english_name]
+                        or lang.replace("-", " ") == country  # noqa
+                    ) and lang not in self.languages:
+                        parse_next = True
+                        lang_parts = lang_id.split("-")
+                        if len(lang_parts) == 2:
+                            self.languages.append(
+                                lang_parts[0] + "-" + lang_parts[1].upper()
+                            )
+                        else:
+                            self.languages.append(lang_id)
+                        # to ensure best match (first match is not necessarily the best one)
+                        if lang == lang_id:
+                            break
 
                 # user may set a valid, yet not selectable language
                 if VALID_LANGUAGE_CODE.match(lang):
diff --git a/searx/utils.py b/searx/utils.py
index d1a28ea249563043eedb2d6de3eb62e0c2744ef3..a48dc36bf18c08839084ba088d92e56514b2adf0 100644
--- a/searx/utils.py
+++ b/searx/utils.py
@@ -3,15 +3,15 @@ import hashlib
 import hmac
 import os
 import re
+from importlib.machinery import SourceFileLoader
 
 from babel.core import get_global
 from babel.dates import format_date
 from babel import UnknownLocaleError
 from codecs import getincrementalencoder
-from imp import load_source
 from numbers import Number
 from os.path import splitext, join
-from io import open
+from pathlib import Path
 from random import choice
 import sys
 import json
@@ -19,7 +19,6 @@ import json
 from searx import settings
 from searx.version import VERSION_STRING
 from searx.languages import language_codes
-from searx import settings
 from searx import logger
 
 from io import StringIO
@@ -31,8 +30,8 @@ logger = logger.getChild('utils')
 blocked_tags = ('script',
                 'style')
 
-useragents = json.loads(open(os.path.dirname(os.path.realpath(__file__))
-                             + "/data/useragents.json", 'r', encoding='utf-8').read())
+with open(Path(__file__).parent / "data" / "useragents.json", encoding='utf-8') as fd:
+    useragents = json.load(fd)
 
 
 def searx_useragent():
@@ -161,7 +160,7 @@ def get_resources_directory(searx_directory, subdirectory, resources_directory):
     if not resources_directory:
         resources_directory = os.path.join(searx_directory, subdirectory)
     if not os.path.isdir(resources_directory):
-        raise Exception(directory + " is not a directory")
+        raise Exception(resources_directory + " is not a directory")
     return resources_directory
 
 
@@ -356,7 +355,7 @@ def load_module(filename, module_dir):
     if modname in sys.modules:
         del sys.modules[modname]
     filepath = join(module_dir, filename)
-    module = load_source(modname, filepath)
+    module = SourceFileLoader(modname, filepath).load_module()
     module.name = modname
     return module
 
diff --git a/searx/webapp.py b/searx/webapp.py
index 84f9a504edc215a4d9648510110205d5c57b4410..22f8eb143e5c0675ca1179f0a32d5b9f4b9156a7 100644
--- a/searx/webapp.py
+++ b/searx/webapp.py
@@ -17,17 +17,10 @@ along with searx. If not, see < http://www.gnu.org/licenses/ >.
 (C) 2013- by Adam Tauber, <asciimoo@gmail.com>
 '''
 
-if __name__ == '__main__':
-    from sys import path
-    from os.path import realpath, dirname
-
-    path.append(realpath(dirname(realpath(__file__)) + '/../'))
-
 import hashlib
 import hmac
 import json
 import os
-import sys
 import time
 import copy
 
@@ -35,21 +28,15 @@ import requests
 
 from searx import logger
 
-logger = logger.getChild('webapp')
 
-try:
-    from pygments import highlight
-    from pygments.lexers import get_lexer_by_name
-    from pygments.util import ClassNotFound
-    from pygments.formatters import HtmlFormatter
-except ImportError:
-    logger.critical("cannot import dependency: pygments")
-    from sys import exit
+from pygments import highlight
+from pygments.lexers import get_lexer_by_name
+from pygments.util import ClassNotFound
+from pygments.formatters import HtmlFormatter
 
-    exit(1)
 from html import escape
 from datetime import datetime, timedelta
-from werkzeug.contrib.fixers import ProxyFix
+from werkzeug.middleware.proxy_fix import ProxyFix
 from flask import (
     Flask, request, render_template, url_for, Response, make_response,
     redirect, send_from_directory
@@ -80,19 +67,11 @@ from searx.url_utils import urlencode, urlparse, urljoin
 from searx.utils import new_hmac
 import threading
 
-# check if the pyopenssl package is installed.
-# It is needed for SSL connection without trouble, see #298
-try:
-    import OpenSSL.SSL  # NOQA
-except ImportError:
-    logger.critical("The pyopenssl package has to be installed.\n"
-                    "Some HTTPS connections will fail")
-
-from io import StringIO
-
 # serve pages with HTTP/1.1
 from werkzeug.serving import WSGIRequestHandler
 
+logger = logger.getChild('webapp')
+
 WSGIRequestHandler.protocol_version = "HTTP/{}".format(settings['server'].get('http_protocol_version', '1.0'))
 
 # about static
@@ -319,10 +298,11 @@ def render(template_name, override_theme=None, **kwargs):
 
     if 'categories' not in kwargs:
         kwargs['categories'] = ['general']
-        kwargs['categories'].extend(x for x in
-                                    sorted(categories.keys())
-                                    if x != 'general'
-                                    and x in enabled_categories)
+        kwargs["categories"].extend(
+            x
+            for x in sorted(categories.keys())
+            if x != "general" and x in enabled_categories
+        )
 
     if 'all_categories' not in kwargs:
         kwargs['all_categories'] = ['general']
@@ -428,7 +408,7 @@ def pre_request():
     else:
         try:
             preferences.parse_dict(request.form)
-        except Exception as e:
+        except Exception:
             logger.exception('invalid settings')
             request.errors.append(gettext('Invalid settings'))
 
@@ -444,8 +424,9 @@ def pre_request():
     allowed_plugins = preferences.plugins.get_enabled()
     disabled_plugins = preferences.plugins.get_disabled()
     for plugin in plugins:
-        if ((plugin.default_on and plugin.id not in disabled_plugins)
-                or plugin.id in allowed_plugins):
+        if (
+            plugin.default_on and plugin.id not in disabled_plugins
+        ) or plugin.id in allowed_plugins:
             request.user_plugins.append(plugin)
 
 
@@ -644,7 +625,6 @@ def preferences():
 
     # render preferences
     image_proxy = request.preferences.get_value('image_proxy')
-    lang = request.preferences.get_value('language')
     disabled_engines = request.preferences.engines.get_disabled()
     allowed_plugins = request.preferences.plugins.get_enabled()
 
@@ -690,11 +670,13 @@ def preferences():
 
 
 def _is_selected_language_supported(engine, preferences):
-    language = preferences.get_value('language')
-    return (language == 'all'
-            or match_language(language,
-                              getattr(engine, 'supported_languages', []),
-                              getattr(engine, 'language_aliases', {}), None))
+    language = preferences.get_value("language")
+    return language == "all" or match_language(
+        language,
+        getattr(engine, "supported_languages", []),
+        getattr(engine, "language_aliases", {}),
+        None,
+    )
 
 
 @app.route('/image_proxy', methods=['GET'])