diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 406434df..2461b703 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -7,7 +7,7 @@ Build and test:
   services:
     - docker:dind
   before_script:
-    - apk add black=20.8_beta1-r0 py3-flake8 docker-compose make
+    - apk add black=20.8_beta1-r0 py3-flake8 py3-isort docker-compose make
   script:
     - cd contrib/docker
     - make build
diff --git a/HACKING.md b/HACKING.md
index bb0e9c93..f65807e8 100644
--- a/HACKING.md
+++ b/HACKING.md
@@ -113,26 +113,23 @@ All new Debsources code should be [PEP8][1] compliant and pass [pyflakes][2]
 validation. Before submitting patches, please make sure that the lines of code
 they touch conform to such requirements.
 
-Additionally, `black` [3] is used to format Python source files.
+Additionally, `black` [3] and `isort` [4] are used to format Python source
+files.
 
 [1]: https://www.python.org/dev/peps/pep-0008/
 [2]: https://pypi.python.org/pypi/pyflakes
 [3]: https://black.readthedocs.io/en/stable/
+[4]: https://pycqa.github.io/isort/
 
-If you develop on Debian(-based distros), a good way to check that this is the
-case is:
-
-    # apt-get install python-flake8
-    $ flake8 file1.py file2.py ...
-
-You can check all Debsources Python source files black and flake8 compliance
-with:
+If you develop on Debian(-based distros), a good way to apply formatting and
+check that everything is good is:
 
+    # apt-get install flake8 isort
+    $ python3 -m pip install --user black
+    $ make format
     $ make check
 
-You can add a pre-commit hook to automatically test PEP8 compliance:
+You can add a pre-commit hook to automatically test PEP8 compliance (might be
+outdated):
 
     $ ln -s ../../contrib/git-pre-commit .git/hooks/pre-commit
-
-If you stumble upon Debsources source files that are not flake8-compliant,
-patches that put them back in compliance are more than welcome (hint hint).
diff --git a/Makefile b/Makefile
index ec149b56..fa214ee6 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,8 @@ NOSE = nosetests3
 FLAKE = flake8 --max-line-length 88 --ignore=E203,W503
 # E203 (whitespace before ':') conflicts with black formatting
 # W503 (line break before binary operator), ditto
-BLACK = black --check
+BLACK = black
+ISORT = isort --profile black --dont-follow-links -p debsources
 
 SRCDIR = lib/debsources
 BINDIR = bin
@@ -32,7 +33,13 @@ test-coverage:
 
 check:
 	$(FLAKE) $(SRCDIR)/ $(shell grep -H 'env python' $(BINDIR)/debsources-* | cut -f 1 -d :)
+	$(BLACK) --check $(SRCDIR)
+# deactivated for now - until isort>=5 is available on Alpine Linux for CICD pipeline
+# $(ISORT) --check $(SRCDIR) $(BINDIR)
+
+format:
 	$(BLACK) $(SRCDIR)
+	$(ISORT) $(SRCDIR) $(BINDIR)
 
 test-online-app:
 	contrib/test-online-app
diff --git a/bin/debsources-bulk-insert-checksums b/bin/debsources-bulk-insert-checksums
index 05ec01d1..f383fff6 100755
--- a/bin/debsources-bulk-insert-checksums
+++ b/bin/debsources-bulk-insert-checksums
@@ -12,16 +12,14 @@
 # see the COPYING file at the top-level directory of this distribution and at
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
-from __future__ import absolute_import
 
 import argparse
 import logging
 
-from sqlalchemy import create_engine, bindparam, LargeBinary
+from sqlalchemy import LargeBinary, bindparam, create_engine
 from sqlalchemy.sql import text as sql_query
 
-from debsources import mainlib
-from debsources import fs_storage
+from debsources import fs_storage, mainlib
 from debsources.plugins.hook_checksums import parse_checksums
 
 METADATA_SUFFIX = ".checksums"
diff --git a/bin/debsources-bulk-insert-ctags b/bin/debsources-bulk-insert-ctags
index 752f1d83..f071660b 100755
--- a/bin/debsources-bulk-insert-ctags
+++ b/bin/debsources-bulk-insert-ctags
@@ -12,18 +12,14 @@
 # see the COPYING file at the top-level directory of this distribution and at
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
-from __future__ import absolute_import
 
 import argparse
 import logging
 
-
-from debsources import mainlib
-
-from sqlalchemy import create_engine, bindparam, LargeBinary
+from sqlalchemy import LargeBinary, bindparam, create_engine
 from sqlalchemy.sql import text as sql_query
 
-from debsources import fs_storage
+from debsources import fs_storage, mainlib
 from debsources.plugins.hook_ctags import parse_ctags
 
 METADATA_SUFFIX = ".ctags"
diff --git a/bin/debsources-dbadmin b/bin/debsources-dbadmin
index 0d665831..7a764b76 100755
--- a/bin/debsources-dbadmin
+++ b/bin/debsources-dbadmin
@@ -12,8 +12,6 @@
 # see the COPYING file at the top-level directory of this distribution and at
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
-from __future__ import absolute_import
-from __future__ import print_function
 
 import argparse
 import time
@@ -22,7 +20,6 @@ from sqlalchemy import create_engine
 
 from debsources.models import Base
 
-
 if __name__ == "__main__":
     start_time = time.time()
 
diff --git a/bin/debsources-fsck b/bin/debsources-fsck
index afd5fbca..91f69314 100755
--- a/bin/debsources-fsck
+++ b/bin/debsources-fsck
@@ -14,7 +14,6 @@
 
 # Check for DB/FS inconsistencies
 
-from __future__ import absolute_import
 
 import argparse
 import logging
@@ -24,10 +23,7 @@ from pathlib import Path
 from sqlalchemy import create_engine
 from sqlalchemy.orm import sessionmaker
 
-from debsources import mainlib
-from debsources import db_storage
-from debsources import fs_storage
-
+from debsources import db_storage, fs_storage, mainlib
 from debsources.debmirror import SourcePackage
 from debsources.models import Package
 
diff --git a/bin/debsources-run-app b/bin/debsources-run-app
index 9396658d..9b85de2e 100755
--- a/bin/debsources-run-app
+++ b/bin/debsources-run-app
@@ -12,8 +12,6 @@
 # see the COPYING file at the top-level directory of this distribution and at
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
-from __future__ import absolute_import
-from __future__ import print_function
 
 import argparse
 
diff --git a/bin/debsources-shell b/bin/debsources-shell
index 32a1a5df..4d28b312 100755
--- a/bin/debsources-shell
+++ b/bin/debsources-shell
@@ -12,16 +12,14 @@
 # see the COPYING file at the top-level directory of this distribution and at
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
-from __future__ import absolute_import
 
+import argparse
 import code
 import os
 import readline
 import rlcompleter  # NOQA
-import argparse
 
-from debsources import mainlib
-from debsources import sqla_session
+from debsources import mainlib, sqla_session
 from debsources.models import *  # NOQA
 
 
diff --git a/bin/debsources-suite-archive b/bin/debsources-suite-archive
index d4bc970c..0aebd4fb 100755
--- a/bin/debsources-suite-archive
+++ b/bin/debsources-suite-archive
@@ -12,18 +12,14 @@
 # see the COPYING file at the top-level directory of this distribution and at
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
-from __future__ import absolute_import
-from __future__ import print_function
 
 import argparse
 import logging
-import sqlalchemy
 import sys
 
+import sqlalchemy
 
-from debsources import archiver
-from debsources import debmirror
-from debsources import mainlib
+from debsources import archiver, debmirror, mainlib
 
 
 def main():
diff --git a/bin/debsources-update b/bin/debsources-update
index 88db813c..dc3c6831 100755
--- a/bin/debsources-update
+++ b/bin/debsources-update
@@ -12,15 +12,14 @@
 # see the COPYING file at the top-level directory of this distribution and at
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
-from __future__ import absolute_import
 
 import argparse
 import logging
-import sqlalchemy
 import sys
 
-from debsources import mainlib
-from debsources import updater
+import sqlalchemy
+
+from debsources import mainlib, updater
 
 
 def main():
diff --git a/lib/debsources/app/app_factory.py b/lib/debsources/app/app_factory.py
index b201eea7..fd20bc8a 100644
--- a/lib/debsources/app/app_factory.py
+++ b/lib/debsources/app/app_factory.py
@@ -12,7 +12,7 @@
 
 
 import logging
-from logging import Formatter, FileHandler, StreamHandler
+from logging import FileHandler, Formatter, StreamHandler
 
 from flask import Flask
 
diff --git a/lib/debsources/app/copyright/routes.py b/lib/debsources/app/copyright/routes.py
index 1c6971e6..05c21703 100644
--- a/lib/debsources/app/copyright/routes.py
+++ b/lib/debsources/app/copyright/routes.py
@@ -11,22 +11,23 @@
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
 
-from flask import jsonify, request, render_template
+from flask import jsonify, render_template, request
+
+from debsources.excepts import Http404Error
 
 from ..helper import bind_render, generic_before_request
-from . import bp_copyright
 from ..views import (
+    ErrorHandler,
     IndexView,
-    PrefixView,
     ListPackagesView,
-    ErrorHandler,
-    Ping,
+    NewsArchiveView,
     PackageVersionsView,
+    Ping,
+    PrefixView,
     SearchView,
-    NewsArchiveView,
 )
-from .views import LicenseView, ChecksumLicenseView, SearchFileView, StatsView
-from debsources.excepts import Http404Error
+from . import bp_copyright
+from .views import ChecksumLicenseView, LicenseView, SearchFileView, StatsView
 
 
 # context vars
diff --git a/lib/debsources/app/copyright/views.py b/lib/debsources/app/copyright/views.py
index fe44b689..94ee52cd 100644
--- a/lib/debsources/app/copyright/views.py
+++ b/lib/debsources/app/copyright/views.py
@@ -11,28 +11,29 @@
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
 
-from collections import defaultdict, Counter
+from collections import Counter, defaultdict
 from functools import cmp_to_key
 from pathlib import Path
 
-from flask import current_app, request
-from debian.debian_support import version_compare
 from debian import copyright
+from debian.debian_support import version_compare
+from flask import current_app, request
 
 import debsources.license_helper as helper
 import debsources.query as qry
 import debsources.statistics as statistics
 from debsources.excepts import (
-    Http404ErrorSuggestions,
     FileOrFolderNotFound,
-    InvalidPackageOrVersionError,
-    Http404MissingCopyright,
     Http404Error,
+    Http404ErrorSuggestions,
+    Http404MissingCopyright,
+    InvalidPackageOrVersionError,
 )
-from ..views import GeneralView, ChecksumView, session, app
-from ..sourcecode import SourceCodeIterator
-from ..pagination import Pagination
+
 from ..extract_stats import extract_stats
+from ..pagination import Pagination
+from ..sourcecode import SourceCodeIterator
+from ..views import ChecksumView, GeneralView, app, session
 
 
 class LicenseView(GeneralView):
diff --git a/lib/debsources/app/doc/routes.py b/lib/debsources/app/doc/routes.py
index 806969f6..27bfcfd7 100644
--- a/lib/debsources/app/doc/routes.py
+++ b/lib/debsources/app/doc/routes.py
@@ -11,10 +11,9 @@
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
 
-from . import bp_doc
-
 from ..helper import bind_render
-from ..views import DocView, AboutView, ErrorHandler
+from ..views import AboutView, DocView, ErrorHandler
+from . import bp_doc
 
 # site errors
 # XXX 500 handler cannot be registered on a blueprint
diff --git a/lib/debsources/app/forms.py b/lib/debsources/app/forms.py
index c519cc60..ad850094 100644
--- a/lib/debsources/app/forms.py
+++ b/lib/debsources/app/forms.py
@@ -11,9 +11,9 @@
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
 
+from flask_wtf import FlaskForm
 from wtforms import TextField
 from wtforms.validators import Required
-from flask_wtf import FlaskForm
 
 
 class SearchForm(FlaskForm):
diff --git a/lib/debsources/app/helper.py b/lib/debsources/app/helper.py
index da4c81c8..b18be12e 100644
--- a/lib/debsources/app/helper.py
+++ b/lib/debsources/app/helper.py
@@ -12,13 +12,14 @@
 
 
 from functools import cmp_to_key, partial
-from debian.debian_support import version_compare
 
-from flask import request, url_for, render_template, redirect
+from debian.debian_support import version_compare
+from flask import redirect, render_template, request, url_for
 
 import debsources.query as qry
+from debsources.excepts import Http404Error, InvalidPackageOrVersionError
 from debsources.models import SuiteAlias
-from debsources.excepts import InvalidPackageOrVersionError, Http404Error
+
 from . import app_wrapper
 
 session = app_wrapper.session
diff --git a/lib/debsources/app/infobox.py b/lib/debsources/app/infobox.py
index 6be56477..a7517580 100644
--- a/lib/debsources/app/infobox.py
+++ b/lib/debsources/app/infobox.py
@@ -11,10 +11,10 @@
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
 
-from flask import url_for, current_app
+from flask import current_app, url_for
 
-from debsources.models import PackageName, Package, Suite, SlocCount, Metric, Ctag
-from debsources.excepts import Http500Error, Http404Error
+from debsources.excepts import Http404Error, Http500Error
+from debsources.models import Ctag, Metric, Package, PackageName, SlocCount, Suite
 
 PTS_PREFIX = "https://tracker.debian.org/pkg/"
 # XXX move this to configuration file?
diff --git a/lib/debsources/app/patches/patches_helper.py b/lib/debsources/app/patches/patches_helper.py
index fbc21484..b945a2b6 100644
--- a/lib/debsources/app/patches/patches_helper.py
+++ b/lib/debsources/app/patches/patches_helper.py
@@ -9,14 +9,13 @@
 # of the License, or (at your option) any later version.  For more information
 # see the COPYING file at the top-level directory of this distribution and at
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
-import re
 import io
 import logging
+import re
 import subprocess
 
 from debsources.navigation import Location, SourceFile
 
-
 ACCEPTED_FORMATS = ["3.0 (quilt)", "3.0 (native)"]
 
 
diff --git a/lib/debsources/app/patches/routes.py b/lib/debsources/app/patches/routes.py
index b0ed8d0f..a312b275 100644
--- a/lib/debsources/app/patches/routes.py
+++ b/lib/debsources/app/patches/routes.py
@@ -11,22 +11,22 @@
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
 
-from flask import jsonify, request, render_template
+from flask import jsonify, render_template, request
 
-from . import bp_patches
+from debsources.excepts import Http404Error
 
 from ..helper import bind_render, generic_before_request
 from ..views import (
+    ErrorHandler,
     IndexView,
+    ListPackagesView,
+    NewsArchiveView,
     Ping,
     PrefixView,
-    ErrorHandler,
-    ListPackagesView,
     SearchView,
-    NewsArchiveView,
 )
-from .views import SummaryView, PatchView, VersionsView
-from debsources.excepts import Http404Error
+from . import bp_patches
+from .views import PatchView, SummaryView, VersionsView
 
 
 # context vars
diff --git a/lib/debsources/app/patches/views.py b/lib/debsources/app/patches/views.py
index 9b9d92bc..9424de6a 100644
--- a/lib/debsources/app/patches/views.py
+++ b/lib/debsources/app/patches/views.py
@@ -12,18 +12,20 @@
 
 
 from collections import OrderedDict
-from flask import request, current_app
 
-from ..views import GeneralView, session
+from flask import current_app, request
+
+import debsources.query as qry
 from debsources.excepts import (
-    Http404ErrorSuggestions,
     FileOrFolderNotFound,
-    InvalidPackageOrVersionError,
     Http404Error,
+    Http404ErrorSuggestions,
+    InvalidPackageOrVersionError,
 )
-import debsources.query as qry
-from ..sourcecode import SourceCodeIterator
+
 from ..pagination import Pagination
+from ..sourcecode import SourceCodeIterator
+from ..views import GeneralView, session
 from . import patches_helper as helper
 
 
diff --git a/lib/debsources/app/sources/routes.py b/lib/debsources/app/sources/routes.py
index e0c3f278..5f6f0038 100644
--- a/lib/debsources/app/sources/routes.py
+++ b/lib/debsources/app/sources/routes.py
@@ -11,26 +11,26 @@
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
 
-from flask import redirect, url_for, request, jsonify, render_template
+from flask import jsonify, redirect, render_template, request, url_for
+
+from debsources.excepts import Http404Error
 
 from ..helper import bind_render, generic_before_request
 from ..views import (
-    IndexView,
-    SearchView,
-    CtagView,
     ChecksumView,
-    PrefixView,
-    ListPackagesView,
-    InfoPackageView,
-    Ping,
+    CtagView,
     ErrorHandler,
-    PackageVersionsView,
+    IndexView,
+    InfoPackageView,
+    ListPackagesView,
     NewsArchiveView,
+    PackageVersionsView,
+    Ping,
+    PrefixView,
+    SearchView,
 )
-
-from .views import StatsView, SourceView
 from . import bp_sources
-from debsources.excepts import Http404Error
+from .views import SourceView, StatsView
 
 
 # context vars
diff --git a/lib/debsources/app/sources/views.py b/lib/debsources/app/sources/views.py
index e156490f..1d285d0e 100644
--- a/lib/debsources/app/sources/views.py
+++ b/lib/debsources/app/sources/views.py
@@ -14,24 +14,26 @@
 import os
 from pathlib import Path
 
-from flask import current_app, request, jsonify, url_for
+from flask import current_app, jsonify, request, url_for
 
-from debsources.excepts import (
-    Http403Error, Http404ErrorSuggestions, Http404Error, FileOrFolderNotFound,
-    InvalidPackageOrVersionError)
-from debsources.consts import SLOCCOUNT_LANGUAGES
+import debsources.query as qry
 from debsources import statistics
-
-from debsources.navigation import (Location, Directory,
-                                   SourceFile)
-
+from debsources.consts import SLOCCOUNT_LANGUAGES
+from debsources.excepts import (
+    FileOrFolderNotFound,
+    Http403Error,
+    Http404Error,
+    Http404ErrorSuggestions,
+    InvalidPackageOrVersionError,
+)
+from debsources.navigation import Directory, Location, SourceFile
 from debsources.url import url_decode, url_encode
-import debsources.query as qry
-from ..views import GeneralView, app, session
+
 from ..extract_stats import extract_stats
+from ..helper import bind_redirect, bind_render
 from ..infobox import Infobox
 from ..sourcecode import SourceCodeIterator
-from ..helper import bind_render, bind_redirect
+from ..views import GeneralView, app, session
 
 
 class StatsView(GeneralView):
diff --git a/lib/debsources/app/views.py b/lib/debsources/app/views.py
index 92d3d2e0..7957426b 100644
--- a/lib/debsources/app/views.py
+++ b/lib/debsources/app/views.py
@@ -13,28 +13,28 @@
 
 from pathlib import Path
 
-from flask import current_app, jsonify, render_template, request, url_for, redirect
+from flask import current_app, jsonify, redirect, render_template, request, url_for
 from flask.views import View
 
+import debsources.query as qry
+from debsources import local_info
+from debsources.consts import SUITES
 from debsources.excepts import (
-    Http500Error,
+    Http403Error,
     Http404Error,
     Http404ErrorSuggestions,
-    Http403Error,
-    InvalidPackageOrVersionError,
     Http404MissingCopyright,
+    Http500Error,
+    InvalidPackageOrVersionError,
 )
 from debsources.models import Package
-import debsources.query as qry
 from debsources.sqla_session import _close_session
-from debsources import local_info
-from debsources.consts import SUITES
 
+from . import app_wrapper
 from .forms import SearchForm
-from .pagination import Pagination
-from .infobox import Infobox
 from .helper import format_big_num, url_for_other_page
-from . import app_wrapper
+from .infobox import Infobox
+from .pagination import Pagination
 
 app = app_wrapper.app
 session = app_wrapper.session
diff --git a/lib/debsources/archiver.py b/lib/debsources/archiver.py
index 89e775b0..af9314a9 100644
--- a/lib/debsources/archiver.py
+++ b/lib/debsources/archiver.py
@@ -19,7 +19,7 @@
 
 from debsources import db_storage, statistics, updater
 from debsources.debmirror import SourcePackage
-from debsources.models import Suite, Package
+from debsources.models import Package, Suite
 
 
 def list_suites(conf, session, archive):
diff --git a/lib/debsources/charts.py b/lib/debsources/charts.py
index f5615956..c68d4716 100644
--- a/lib/debsources/charts.py
+++ b/lib/debsources/charts.py
@@ -13,14 +13,13 @@
 
 import logging
 import operator
+from itertools import cycle
 
 import matplotlib
 
-from itertools import cycle
-
 matplotlib.use("Agg")
-import matplotlib.pyplot as plt  # NOQA
 import matplotlib.cm as cm  # NOQA
+import matplotlib.pyplot as plt  # NOQA
 import numpy as np  # NOQA
 
 
diff --git a/lib/debsources/consts.py b/lib/debsources/consts.py
index fb032d0a..975a18db 100644
--- a/lib/debsources/consts.py
+++ b/lib/debsources/consts.py
@@ -13,7 +13,6 @@
 
 import datetime
 
-
 # Limit on the maximum key length for Postgres columns which are subject to
 # btree indexing. The actual value is 8192, but we play safe and round down.
 # This allows to have complete indexes, rather than partial, which would
diff --git a/lib/debsources/db_storage.py b/lib/debsources/db_storage.py
index 311b9393..78015489 100644
--- a/lib/debsources/db_storage.py
+++ b/lib/debsources/db_storage.py
@@ -14,8 +14,7 @@
 import logging
 
 from debsources import fs_storage
-from debsources.models import File, Package, PackageName, SuiteInfo, Suite
-from debsources.models import VCS_TYPES
+from debsources.models import VCS_TYPES, File, Package, PackageName, Suite, SuiteInfo
 
 
 def add_package(session, pkg, pkgdir, sticky=False):
diff --git a/lib/debsources/debmirror.py b/lib/debsources/debmirror.py
index 14e80b5b..1a18386c 100644
--- a/lib/debsources/debmirror.py
+++ b/lib/debsources/debmirror.py
@@ -13,11 +13,11 @@
 
 import logging
 import lzma
-import magic
 import os
 from pathlib import Path
 from typing import Optional
 
+import magic
 from debian import deb822
 
 # supported compression formats for Sources files. Order does matter: formats
diff --git a/lib/debsources/filetype.py b/lib/debsources/filetype.py
index 09b889a2..fcdc2340 100644
--- a/lib/debsources/filetype.py
+++ b/lib/debsources/filetype.py
@@ -13,7 +13,6 @@
 
 import re
 
-
 # Languages constants
 (
     PYTHON,
diff --git a/lib/debsources/license_helper.py b/lib/debsources/license_helper.py
index 47fd1dad..62bfa183 100644
--- a/lib/debsources/license_helper.py
+++ b/lib/debsources/license_helper.py
@@ -13,8 +13,8 @@
 import logging
 import re
 
-from flask import url_for
 from debian import copyright
+from flask import url_for
 
 from debsources.navigation import Location
 
diff --git a/lib/debsources/models.py b/lib/debsources/models.py
index 8d22d38f..204fd407 100644
--- a/lib/debsources/models.py
+++ b/lib/debsources/models.py
@@ -14,22 +14,30 @@
 import warnings
 from pathlib import Path
 
-from sqlalchemy import Column, ForeignKey
-from sqlalchemy import UniqueConstraint, PrimaryKeyConstraint
-from sqlalchemy import Index
-from sqlalchemy import Boolean, Date, DateTime, Integer, String
+import sqlalchemy.types
+from sqlalchemy import (
+    Boolean,
+    Column,
+    Date,
+    DateTime,
+    Enum,
+    ForeignKey,
+    Index,
+    Integer,
+    PrimaryKeyConstraint,
+    String,
+    UniqueConstraint,
+)
 from sqlalchemy.dialects.postgresql import BIGINT
-from sqlalchemy import Enum
-from sqlalchemy.orm import relationship
 from sqlalchemy.ext.declarative import declarative_base
-import sqlalchemy.types
+from sqlalchemy.orm import relationship
 
 from debsources.consts import (
-    VCS_TYPES,
-    SLOCCOUNT_LANGUAGES,
+    COPYRIGHT_ORACLES,
     CTAGS_LANGUAGES,
     METRIC_TYPES,
-    COPYRIGHT_ORACLES,
+    SLOCCOUNT_LANGUAGES,
+    VCS_TYPES,
 )
 
 Base = declarative_base()
diff --git a/lib/debsources/navigation.py b/lib/debsources/navigation.py
index a3b0057f..c026f482 100644
--- a/lib/debsources/navigation.py
+++ b/lib/debsources/navigation.py
@@ -11,19 +11,19 @@
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
 
-import magic
 import fnmatch
 from pathlib import Path
 
+import magic
 from sqlalchemy import and_
 
-from debsources.models import Checksum, File, Package, PackageName
+import debsources.query as qry
 from debsources import filetype
-from debsources.url import url_encode
 from debsources.consts import AREAS
 from debsources.debmirror import SourcePackage
 from debsources.excepts import FileOrFolderNotFound, InvalidPackageOrVersionError
-import debsources.query as qry
+from debsources.models import Checksum, File, Package, PackageName
+from debsources.url import url_encode
 
 
 class Location(object):
diff --git a/lib/debsources/plugins/hook_checksums.py b/lib/debsources/plugins/hook_checksums.py
index 1f5ad8eb..4662314f 100644
--- a/lib/debsources/plugins/hook_checksums.py
+++ b/lib/debsources/plugins/hook_checksums.py
@@ -17,12 +17,9 @@
 
 from sqlalchemy import sql
 
-from debsources import db_storage
-from debsources import hashutil
-
+from debsources import db_storage, hashutil
 from debsources.models import Checksum, File
 
-
 conf = None
 
 MY_NAME = "checksums"
diff --git a/lib/debsources/plugins/hook_copyright.py b/lib/debsources/plugins/hook_copyright.py
index cfda0077..dab08fee 100644
--- a/lib/debsources/plugins/hook_copyright.py
+++ b/lib/debsources/plugins/hook_copyright.py
@@ -19,8 +19,8 @@
 from debian import copyright
 
 from debsources import db_storage
-from debsources.models import FileCopyright, File
 from debsources import license_helper as helper
+from debsources.models import File, FileCopyright
 
 conf = None
 
diff --git a/lib/debsources/plugins/hook_ctags.py b/lib/debsources/plugins/hook_ctags.py
index 38fb4cf1..9a3db4d1 100644
--- a/lib/debsources/plugins/hook_ctags.py
+++ b/lib/debsources/plugins/hook_ctags.py
@@ -19,10 +19,8 @@
 from sqlalchemy import sql
 
 from debsources import db_storage
-
-from debsources.models import Ctag, File
 from debsources.consts import MAX_KEY_LENGTH
-
+from debsources.models import Ctag, File
 
 conf = None
 
diff --git a/lib/debsources/plugins/hook_metrics.py b/lib/debsources/plugins/hook_metrics.py
index c88a58f3..aeaffa34 100644
--- a/lib/debsources/plugins/hook_metrics.py
+++ b/lib/debsources/plugins/hook_metrics.py
@@ -17,10 +17,8 @@
 from pathlib import Path
 
 from debsources import db_storage
-
 from debsources.models import Metric
 
-
 conf = None
 
 MY_NAME = "metrics"
diff --git a/lib/debsources/plugins/hook_sloccount.py b/lib/debsources/plugins/hook_sloccount.py
index cf3e1603..9cbfb95d 100644
--- a/lib/debsources/plugins/hook_sloccount.py
+++ b/lib/debsources/plugins/hook_sloccount.py
@@ -20,7 +20,6 @@
 from debsources import db_storage
 from debsources.models import SlocCount
 
-
 conf = None
 
 SLOCCOUNT_FLAGS = ["--addlangall"]
diff --git a/lib/debsources/query.py b/lib/debsources/query.py
index d554b71d..b938d043 100644
--- a/lib/debsources/query.py
+++ b/lib/debsources/query.py
@@ -11,30 +11,29 @@
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
 
-from functools import cmp_to_key
-from pathlib import Path
 import os
 import stat
-
-from sqlalchemy import func as sql_func, not_
 from collections import namedtuple
+from functools import cmp_to_key
+from pathlib import Path
 
 from debian.debian_support import version_compare
-from debsources.url import url_encode
-from debsources.consts import PREFIXES_DEFAULT
-from debsources.consts import SUITES
+from sqlalchemy import func as sql_func
+from sqlalchemy import not_
+
+from debsources.consts import PREFIXES_DEFAULT, SUITES
 from debsources.excepts import InvalidPackageOrVersionError
 from debsources.models import (
     Checksum,
     Ctag,
     File,
+    FileCopyright,
     Package,
     PackageName,
     Suite,
     SuiteInfo,
-    FileCopyright,
 )
-
+from debsources.url import url_encode
 
 LongFMT = namedtuple("LongFMT", ["type", "perms", "size", "symlink_dest"])
 
diff --git a/lib/debsources/sqla_session.py b/lib/debsources/sqla_session.py
index 2f326494..69dc4952 100644
--- a/lib/debsources/sqla_session.py
+++ b/lib/debsources/sqla_session.py
@@ -12,7 +12,7 @@
 
 
 from sqlalchemy import create_engine
-from sqlalchemy.orm import sessionmaker, scoped_session
+from sqlalchemy.orm import scoped_session, sessionmaker
 
 
 def _get_engine_session(url, verbose=True):
diff --git a/lib/debsources/statistics.py b/lib/debsources/statistics.py
index fafcf1f7..1610d4af 100644
--- a/lib/debsources/statistics.py
+++ b/lib/debsources/statistics.py
@@ -19,23 +19,23 @@
 import re
 from pathlib import Path
 
-from sqlalchemy import distinct, desc
+from sqlalchemy import desc, distinct
 from sqlalchemy import func as sql_func
 
 from debsources.consts import SLOCCOUNT_LANGUAGES, SUITES
+from debsources.license_helper import Licenses
 from debsources.models import (
     Checksum,
     Ctag,
+    File,
+    FileCopyright,
     Metric,
+    Package,
+    PackageName,
     SlocCount,
     Suite,
     SuiteInfo,
-    Package,
-    PackageName,
-    FileCopyright,
-    File,
 )
-from debsources.license_helper import Licenses
 
 
 def _count(query):
diff --git a/lib/debsources/tests/db_testing.py b/lib/debsources/tests/db_testing.py
index 6640e450..12ced605 100644
--- a/lib/debsources/tests/db_testing.py
+++ b/lib/debsources/tests/db_testing.py
@@ -11,15 +11,14 @@
 # https://salsa.debian.org/qa/debsources/blob/master/COPYING
 
 
-import sqlalchemy
-import sqlalchemy.orm
 import subprocess
 
+import sqlalchemy
+import sqlalchemy.orm
 
 from debsources.subprocess_workaround import subprocess_setup
 from debsources.tests.testdata import TEST_DATA_DIR, TEST_DB_NAME
 
-
 TEST_DB_DUMP = TEST_DATA_DIR / "db" / "pg-dump-custom"
 
 # queries to compare two DB schemas (e.g. "public.*" and "ref.*")
diff --git a/lib/debsources/tests/test_archiver.py b/lib/debsources/tests/test_archiver.py
index 4b4582cc..0c1d0324 100644
--- a/lib/debsources/tests/test_archiver.py
+++ b/lib/debsources/tests/test_archiver.py
@@ -17,20 +17,14 @@
 import unittest
 from pathlib import Path
 
-from nose.tools import istest
 from nose.plugins.attrib import attr
+from nose.tools import istest
 
-from debsources import archiver
-from debsources import db_storage
-from debsources import debmirror
-from debsources import mainlib
-from debsources import statistics
-from debsources import updater
-
+from debsources import archiver, db_storage, debmirror, mainlib, statistics, updater
 from debsources.consts import DEBIAN_RELEASES
 from debsources.tests.db_testing import DbTestFixture
-from debsources.tests.updater_testing import mk_conf
 from debsources.tests.testdata import TEST_DATA_DIR
+from debsources.tests.updater_testing import mk_conf
 
 
 @attr("infra")
diff --git a/lib/debsources/tests/test_filetype.py b/lib/debsources/tests/test_filetype.py
index 6110fa13..60290d5b 100644
--- a/lib/debsources/tests/test_filetype.py
+++ b/lib/debsources/tests/test_filetype.py
@@ -13,11 +13,19 @@
 
 import unittest
 
-from nose.tools import istest
 from nose.plugins.attrib import attr
+from nose.tools import istest
 
-from debsources.filetype import get_filetype, get_highlightjs_language
-from debsources.filetype import HTML, PHP, PYTHON, RUBY, XML, MAKEFILE
+from debsources.filetype import (
+    HTML,
+    MAKEFILE,
+    PHP,
+    PYTHON,
+    RUBY,
+    XML,
+    get_filetype,
+    get_highlightjs_language,
+)
 
 
 @attr("filetype")
diff --git a/lib/debsources/tests/test_fs_storage.py b/lib/debsources/tests/test_fs_storage.py
index 0a7479bb..e168fce7 100644
--- a/lib/debsources/tests/test_fs_storage.py
+++ b/lib/debsources/tests/test_fs_storage.py
@@ -13,8 +13,8 @@
 
 import unittest
 
-from nose.tools import istest
 from nose.plugins.attrib import attr
+from nose.tools import istest
 
 from debsources.fs_storage import parse_path, walk
 from debsources.tests.testdata import TEST_DATA_DIR
diff --git a/lib/debsources/tests/test_hashutil.py b/lib/debsources/tests/test_hashutil.py
index 36064732..e4983593 100644
--- a/lib/debsources/tests/test_hashutil.py
+++ b/lib/debsources/tests/test_hashutil.py
@@ -14,8 +14,8 @@
 import unittest
 from pathlib import Path
 
-from nose.tools import istest
 from nose.plugins.attrib import attr
+from nose.tools import istest
 
 from debsources.hashutil import sha256sum
 from debsources.tests.testdata import TEST_DATA_DIR
diff --git a/lib/debsources/tests/test_stats.py b/lib/debsources/tests/test_stats.py
index b83f7041..fdf254ad 100644
--- a/lib/debsources/tests/test_stats.py
+++ b/lib/debsources/tests/test_stats.py
@@ -13,11 +13,10 @@
 
 import unittest
 
-from nose.tools import istest
 from nose.plugins.attrib import attr
+from nose.tools import istest
 
 from debsources import statistics
-
 from debsources.tests.db_testing import DbTestFixture
 
 
diff --git a/lib/debsources/tests/test_updater.py b/lib/debsources/tests/test_updater.py
index 84b60efa..6b89d3a3 100644
--- a/lib/debsources/tests/test_updater.py
+++ b/lib/debsources/tests/test_updater.py
@@ -15,25 +15,20 @@
 import logging
 import os
 import shutil
-import sqlalchemy
 import subprocess
 import tempfile
 import unittest
 from pathlib import Path
 
-from nose.tools import istest
+import sqlalchemy
 from nose.plugins.attrib import attr
+from nose.tools import istest
 
-from debsources import db_storage
-from debsources import mainlib
-from debsources import models
-from debsources import statistics
-from debsources import updater
-
-from debsources.tests.db_testing import DbTestFixture, DB_COMPARE_QUERIES
-from debsources.tests.updater_testing import mk_conf
+from debsources import db_storage, mainlib, models, statistics, updater
 from debsources.subprocess_workaround import subprocess_setup
+from debsources.tests.db_testing import DB_COMPARE_QUERIES, DbTestFixture
 from debsources.tests.testdata import TEST_DATA_DIR
+from debsources.tests.updater_testing import mk_conf
 
 
 def compare_dirs(dir1, dir2, exclude=[]):
diff --git a/lib/debsources/tests/updater_testing.py b/lib/debsources/tests/updater_testing.py
index d8b25780..5c8d30d0 100644
--- a/lib/debsources/tests/updater_testing.py
+++ b/lib/debsources/tests/updater_testing.py
@@ -13,7 +13,7 @@
 
 from pathlib import Path
 
-from debsources.tests.testdata import TEST_DIR, TEST_DB_NAME, TEST_DATA_DIR
+from debsources.tests.testdata import TEST_DATA_DIR, TEST_DB_NAME, TEST_DIR
 
 
 def mk_conf(tmpdir: Path):
diff --git a/lib/debsources/updater.py b/lib/debsources/updater.py
index bc8afebe..6fe352ac 100644
--- a/lib/debsources/updater.py
+++ b/lib/debsources/updater.py
@@ -15,31 +15,29 @@
 import logging
 import os
 import subprocess
+from datetime import datetime
+from email.utils import formatdate
 from pathlib import Path
 from typing import List
 
-from datetime import datetime
-from email.utils import formatdate
-from sqlalchemy import sql, not_
-
-from debsources import db_storage
-from debsources import fs_storage
-from debsources import statistics
-from . import query as qry
+from sqlalchemy import not_, sql
 
+from debsources import db_storage, fs_storage, statistics
 from debsources.consts import DEBIAN_RELEASES, SLOCCOUNT_LANGUAGES
 from debsources.debmirror import SourceMirror, SourcePackage
 from debsources.models import (
-    SuiteInfo,
-    Suite,
-    SuiteAlias,
-    Package,
+    HistoryCopyright,
     HistorySize,
     HistorySlocCount,
-    HistoryCopyright,
+    Package,
+    Suite,
+    SuiteAlias,
+    SuiteInfo,
 )
 from debsources.subprocess_workaround import subprocess_setup
 
+from . import query as qry
+
 KNOWN_EVENTS = ["add-package", "rm-package"]
 NO_OBSERVERS = {e: [] for e in KNOWN_EVENTS}