Convert zuul-registry to nox

Tox v4 released and has introduced a number of compatibility problems.
Nox is an alternative to nox that is much simpler and uses standard
tools and zuul repos are switching to it. This change updates
zuul-registry.

Change-Id: I588842a0c47d0591b6dacbe28e96915e1b15819e

.zuul.yaml

@@ -74,17 +74,19 @@
     check:
       jobs:
         - zuul-registry-build-image
-        - tox-pep8
-        - tox-py38
-        - tox-py310:
+        - nox-linters
+        - nox-py38:
+            nodeset: ubuntu-focal
+        - nox-py310:
             nodeset: ubuntu-jammy
         - build-python-release
     gate:
       jobs:
         - zuul-registry-upload-image
-        - tox-pep8
-        - tox-py38
-        - tox-py310:
+        - nox-linters
+        - nox-py38:
+            nodeset: ubuntu-focal
+        - nox-py310:
             nodeset: ubuntu-jammy
         - build-python-release
     promote:

noxfile.py

@@ -0,0 +1,40 @@
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import nox
+
+
+nox.options.error_on_external_run = True
+nox.options.reuse_existing_virtualenvs = True
+nox.options.sessions = ["tests-3", "linters"]
+
+
+@nox.session(python='3')
+def tests(session):
+    session.install('-r', 'requirements.txt',
+                    '-r', 'test-requirements.txt')
+    session.install('-e', '.')
+    session.run('stestr', 'run', '--slowest', *session.posargs)
+
+
+@nox.session(python='3')
+def linters(session):
+    session.install('flake8')
+    session.run('flake8', *session.posargs)
+
+
+@nox.session(python='3')
+def venv(session):
+    session.install('-r', 'requirements.txt',
+                    '-r', 'test-requirements.txt')
+    session.install('-e', '.')
+    session.run(*session.posargs)

setup.cfg

@@ -29,3 +29,10 @@ source-dir = doc/source
 build-dir = doc/build
 all_files = 1
 warning-is-error = 1
+
+[flake8]
+# These are ignored intentionally in zuul projects;
+# please don't submit patches that solely correct them or enable them.
+ignore = E124,E125,E129,E252,E402,E741,H,W503,W504
+show-source = True
+exclude = .venv,.tox,.nox,dist,doc,build,*.egg,node_modules

tox.ini

@@ -20,10 +20,3 @@ commands =
 
 [testenv:venv]
 commands = {posargs}
-
-[flake8]
-# These are ignored intentionally in zuul projects;
-# please don't submit patches that solely correct them or enable them.
-ignore = E124,E125,E129,E252,E402,E741,H,W503,W504
-show-source = True
-exclude = .venv,.tox,dist,doc,build,*.egg,node_modules