.gitlab-ci.yml

+---
+test stretch:
+  image: debian:stretch
+  script: debian/run-ci
+
+test buster:
+  image: debian:buster
+  script: debian/run-ci
+
+flake8:
+  image: debian:9
+  script:
+    - apt-get update
+    - apt-get install -y flake8
+    - flake8
+  allow_failure: true

debian/run-ci

+#! /bin/bash
+#
+# © 2018 Ansgar Burchardt <ansgar@debian.org>
+# License: GPL-2+
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+set -eu
+
+if [ ! -f dak/dak.py ]; then
+  echo >&2 "E: run-ci must be invoked in the root directory of dak"
+  exit 1
+fi
+
+apt-get update
+apt-get install -y build-essential
+apt-get build-dep -y .
+dpkg-buildpackage -b

setup.cfg

+[flake8]
+ignore =
+ # continuation line missing indentation or outdented
+ E122,
+ # expected 2 blank lines
+ E302,
+ # line too long
+ E501,