Fix ifconfig flags tests, run in Python 3 CI

- Python 2 CI image has an old net-tools (hence ifconfig) version
with a non-easily-parsable flags format, making tests fail.
- Python 3 musllinux CI image has a busybox-provided ifconfig
with the same format as old net-tools.
- Python 3 manylinux CI image does not have net-tools (hence ifconfig)
pre-installed, so tests using it were skippied altogether.

Signed-off-by: Ben Raz <[email protected]>

.github/workflows/build.yml

@@ -33,7 +33,8 @@ jobs:
         include:
           - {name: Linux, python: '3.9', os: ubuntu-latest}
     env:
-      CIBW_BEFORE_ALL_LINUX: command -v apk && apk --no-cache add coreutils procps || true
+      CIBW_BEFORE_ALL_LINUX: command -v apk && apk --no-cache add coreutils procps ||
+                             (yum install -y net-tools && yum clean all)
       CIBW_TEST_COMMAND:
         PYTHONWARNINGS=always PYTHONUNBUFFERED=1 PSUTIL_DEBUG=1 python {project}/psutil/tests/runner.py &&
         PYTHONWARNINGS=always PYTHONUNBUFFERED=1 PSUTIL_DEBUG=1 python {project}/psutil/tests/test_memleaks.py

psutil/tests/test_linux.py

@@ -204,6 +204,18 @@ def get_free_version_info():
     return tuple(map(int, out.split()[-1].split('.')))
 
 
+def ifconfig_has_flags():
+    """
+    Parse 'ifconfig' command output and determine whether
+    it exposes easily-parsable flags for interfaces or not.
+    """
+    if not which('ifconfig'):
+        return False
+
+    out = sh(['ifconfig']).strip()
+    return 'flags=' in out
+
+
 @contextlib.contextmanager
 def mock_open_content(for_path, content):
     """Mock open() builtin and forces it to return a certain `content`
@@ -993,7 +1005,10 @@ def test_mtu(self):
             with open("/sys/class/net/%s/mtu" % name, "rt") as f:
                 self.assertEqual(stats.mtu, int(f.read().strip()))
 
-    @unittest.skipIf(not which("ifconfig"), "ifconfig utility not available")
+    @unittest.skipIf(not which("ifconfig"),
+                     "ifconfig utility not available")
+    @unittest.skipIf(not ifconfig_has_flags(),
+                     "ifconfig utility doesn't expose flags in a known format")
     def test_flags(self):
         # first line looks like this:
         # "eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500"
@@ -1023,7 +1038,7 @@ class TestSystemNetIOCounters(PsutilTestCase):
     def test_against_ifconfig(self):
         def ifconfig(nic):
             ret = {}
-            out = sh("ifconfig %s" % name)
+            out = sh("ifconfig %s" % nic)
             ret['packets_recv'] = int(
                 re.findall(r'RX packets[: ](\d+)', out)[0])
             ret['packets_sent'] = int(