versionutils: switch from pkg_resources to packaging

Importing pkg_resources has a side-effect of scanning the metadata of
every installed python package. That is excessive overhead for a
function that needs to compare two version strings.

This change replaces pkg_resources with the packaging library, which
is also used as the implementation for version parsing within
setuptools and pkg_resources.

Change-Id: Ic9bda0783d3664e1f518d513d81b3271028335fd
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

lower-constraints.txt

@@ -19,6 +19,7 @@ os-client-config==1.28.0
 oslo.config==5.2.0
 oslo.i18n==3.15.3
 oslotest==3.2.0
+packaging==20.4
 pbr==2.0.0
 pyparsing==2.1.0
 python-mimeparse==1.6.0

oslo_utils/versionutils.py

@@ -19,7 +19,7 @@ Helpers for comparing version strings.
 .. versionadded:: 1.6
 """
 
-import pkg_resources
+import packaging.version
 import six
 
 from oslo_utils._i18n import _
@@ -39,17 +39,14 @@ def is_compatible(requested_version, current_version, same_major=True):
         True.
     :returns: True if compatible, False if not
     """
-    requested_parts = pkg_resources.parse_version(requested_version)
-    current_parts = pkg_resources.parse_version(current_version)
+    requested = packaging.version.Version(requested_version)
+    current = packaging.version.Version(current_version)
 
     if same_major:
-        # NOTE(jlvillal) pkg_resources issues a warning if we try to access
-        # portions of the version, for example requested_parts[0] will issue a
-        # warning message. So get the major_version from the string instead.
-        if requested_version.split('.')[0] != current_version.split('.')[0]:
+        if requested.major != current.major:
             return False
 
-    return current_parts >= requested_parts
+    return current >= requested
 
 
 def convert_version_to_int(version):

requirements.txt

@@ -16,3 +16,4 @@ netaddr>=0.7.18 # BSD
 netifaces>=0.10.4 # MIT
 debtcollector>=1.2.0 # Apache-2.0
 pyparsing>=2.1.0 # MIT
+packaging>=20.4 # BSD