feat: Support Python 3.12

* Replace the use of pkg_resources (from setuptools, which is no
  longer included in virtual environments as of 3.12) with
  importlib.metadata and importlib.resources.
* Add a dependency on the importlib-resources library for Python<3.9
  (importlib.resources became part of the standard library in 3.9;
  importlib-resources is a backport for older versions).
* Add Python 3.12 to the test matrix.
* Update the Trove classifiers in setup.py: drop support for Python
  3.6 and 3.7, add support for Python 3.12.

References:
https://importlib-resources.readthedocs.io/en/latest/migration.html

.github/workflows/tox.yml

@@ -14,6 +14,7 @@ jobs:
           - '3.9'
           - '3.10'
           - '3.11'
+          - '3.12'
 
     steps:
     - name: Check out code

CHANGELOG.md

@@ -1,3 +1,7 @@
+## Unreleased
+
+* feat: Support Python 3.12.
+
 ## Version 1.3.2 (2024-01-22)
 
 * fix: Un-break cluster template creation with `openstacksdk>=1.0.0`.

setup.py

@@ -44,11 +44,10 @@ def load_readme():
         "License :: OSI Approved :: GNU Affero General Public License v3",
         "Operating System :: OS Independent",
         "Programming Language :: Python",
-        "Programming Language :: Python :: 3.6",
-        "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
         "Programming Language :: Python :: 3.10",
         "Programming Language :: Python :: 3.11",
+        "Programming Language :: Python :: 3.12",
     ],
 )

tox.ini

@@ -1,12 +1,13 @@
 [tox]
-envlist = gitlint,py{38,39,310,311},flake8
+envlist = gitlint,py{38,39,310,311,312},flake8
 
 [gh-actions]
 python =
     3.8: gitlint,py38,flake8
     3.9: gitlint,py39,flake8
     3.10: gitlint,py310,flake8
     3.11: gitlint,py311,flake8
+    3.12: gitlint,py312,flake8
 
 [flake8]
 ignore = E124,W504

tutoropenstack/__about__.py

@@ -8,6 +8,5 @@
 https://packaging.python.org/guides/single-sourcing-package-version/
 """
 
-import pkg_resources
-__version__ = pkg_resources.get_distribution(
-    'tutor-contrib-openstack').version
+from importlib import metadata
+__version__ = metadata.version('tutor-contrib-openstack')

tutoropenstack/plugin.py

@@ -1,10 +1,26 @@
 """Plugin definition for the Tutor openstack plugin."""
 
-from glob import glob
 from .command import openstack as openstack_command
 
 import os
-import pkg_resources
+
+# importlib.resources is the standard library module, available since
+# Python 3.7. importlib_resources is the backport for older Python
+# versions. Normally, we would attempt to import importlib.resources,
+# and fall back to importlib_resources on ImportError.
+#
+# However, in this case we need the files attribute, which was only
+# added in 3.9. Thus, we install importlib_resources as a library on
+# 3.8 and try to import it here. If importlib_resources is *not*
+# installed as a library, we assume we're on 3.9 or later, where we
+# can use importlib.resources.files rather than
+# importlib_resources.files.
+#
+# Confused yet?
+try:
+    import importlib_resources as resources
+except ImportError:
+    from importlib import resources
 
 from tutor import hooks
 
@@ -31,9 +47,10 @@
 hooks.Filters.CLI_COMMANDS.add_item(openstack_command)
 
 # Add the "templates" folder as a template root
-hooks.Filters.ENV_TEMPLATE_ROOTS.add_item(
-    pkg_resources.resource_filename("tutoropenstack", "templates")
-)
+templates = resources.files('tutoropenstack') / 'templates'
+with resources.as_file(templates) as path:
+    hooks.Filters.ENV_TEMPLATE_ROOTS.add_item(path)
+
 # Render the "build" and "apps" folders
 hooks.Filters.ENV_TEMPLATE_TARGETS.add_items(
     [
@@ -42,12 +59,7 @@
     ],
 )
 # Load patches from files
-for path in glob(
-    os.path.join(
-        pkg_resources.resource_filename("tutoropenstack", "patches"),
-        "*",
-    )
-):
+for path in resources.files('tutoropenstack.patches').iterdir():
     with open(path, encoding="utf-8") as patch_file:
         hooks.Filters.ENV_PATCHES.add_item(
             (os.path.basename(path), patch_file.read())