replace pkg_resources.load_entry_point

pkg_resources is deprecated. Use the corresponding importlib.metadata
interface instead. Use the stdlib version on python >= 3.8 and use the
importlib_metadata backport on older versions.

gunicorn/util.py

@@ -22,7 +22,10 @@ import time
 import traceback
 import warnings
 
-import pkg_resources
+try:
+    import importlib.metadata as importlib_metadata
+except ImportError:
+    import importlib_metadata
 
 from gunicorn.errors import AppImportError
 from gunicorn.workers import SUPPORTED_WORKERS
@@ -54,6 +57,15 @@ except ImportError:
         pass
 
 
+def load_entry_point(distribution, group, name):
+    dist_obj = importlib_metadata.distribution(distribution)
+    eps = [ep for ep in dist_obj.entry_points
+           if ep.group == group and ep.name == name]
+    if not eps:
+        raise ImportError("Entry point %r not found" % ((group, name),))
+    return eps[0].load()
+
+
 def load_class(uri, default="gunicorn.workers.sync.SyncWorker",
                section="gunicorn.workers"):
     if inspect.isclass(uri):
@@ -68,7 +80,7 @@ def load_class(uri, default="gunicorn.workers.sync.SyncWorker",
             name = default
 
         try:
-            return pkg_resources.load_entry_point(dist, section, name)
+            return load_entry_point(dist, section, name)
         except Exception:
             exc = traceback.format_exc()
             msg = "class uri %r invalid or not found: \n\n[%s]"
@@ -85,7 +97,7 @@ def load_class(uri, default="gunicorn.workers.sync.SyncWorker",
                     break
 
                 try:
-                    return pkg_resources.load_entry_point(
+                    return load_entry_point(
                         "gunicorn", section, uri
                     )
                 except Exception:

setup.py

@@ -70,11 +70,7 @@ class PyTestCommand(TestCommand):
 
 
 install_requires = [
-    # We depend on functioning pkg_resources.working_set.add_entry() and
-    # pkg_resources.load_entry_point(). These both work as of 3.0 which
-    # is the first version to support Python 3.4 which we require as a
-    # floor.
-    'setuptools>=3.0',
+    'importlib_metadata; python_version<"3.8"',
     'packaging',
 ]