tests: do not run qemu interface tests if the environment does not allow it

cdf73b9731 has added the qemu tests as part of the default test run,
which results in "make test" failure in more restricted environments which do not allow the
namespace creation.

Add a config flag to skip those tests, and skip them if the namespace creation fails.

Type: test
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>
Change-Id: Ie631f7fb2a80864f77c79619eba4a43712e950e5

test/config.py

@@ -2,6 +2,7 @@ import argparse
 import os
 import psutil
 import time
+from vpp_qemu_utils import can_create_namespaces
 
 
 def positive_int_or_default(default):
@@ -191,6 +192,11 @@ parser.add_argument(
 )
 
 parser.add_argument("--extended", action="store_true", help="run extended tests")
+parser.add_argument(
+    "--skip-netns-tests",
+    action="store_true",
+    help="skip tests involving netns operations",
+)
 
 parser.add_argument(
     "--sanity", action="store_true", help="perform sanity vpp run before running tests"
@@ -444,6 +450,10 @@ elif config.max_vpp_cpus > 0:
 else:
     max_vpp_cpus = num_cpus
 
+if not config.skip_netns_tests:
+    if not can_create_namespaces():
+        config.skip_netns_tests = True
+
 if __name__ == "__main__":
     print("Provided arguments:")
     for i in config.__dict__:

test/test_vm_vpp_interfaces.py

@@ -63,6 +63,9 @@ layer3 = test_config["L3"]
 def create_test(test_name, test, ip_version, mtu):
     """Create and return a unittest method for a test."""
 
+    @unittest.skipIf(
+        config.skip_netns_tests, "netns not available or disabled from cli"
+    )
     def test_func(self):
         self.logger.debug(f"Starting unittest:{test_name}")
         self.setUpTestToplogy(test=test, ip_version=ip_version)
@@ -97,6 +100,8 @@ def create_test(test_name, test, ip_version, mtu):
 
 def generate_vpp_interface_tests():
     """Generate unittests for testing vpp interfaces."""
+    if config.skip_netns_tests:
+        print("Skipping netns tests")
     for test in tests:
         for ip_version in test_config["ip_versions"]:
             for mtu in test_config["mtus"]:

test/vpp_qemu_utils.py

@@ -6,6 +6,22 @@ import subprocess
 import sys
 
 
+def can_create_namespaces():
+    """Check if the environment allows creating the namespaces"""
+
+    try:
+        namespace = "vpp_chk_4212"
+        result = subprocess.run(["ip", "netns", "add", namespace], capture_output=True)
+        if result.returncode != 0:
+            return False
+        result = subprocess.run(["ip", "netns", "del", namespace], capture_output=True)
+        if result.returncode != 0:
+            return False
+        return True
+    except:
+        return False
+
+
 def create_namespace(ns):
     """create one or more namespaces.
 
@@ -18,7 +34,9 @@ def create_namespace(ns):
         namespaces = ns
     try:
         for namespace in namespaces:
-            subprocess.run(["ip", "netns", "add", namespace])
+            result = subprocess.run(["ip", "netns", "add", namespace])
+            if result.returncode != 0:
+                raise Exception(f"Error while creating namespace {namespace}")
     except subprocess.CalledProcessError as e:
         raise Exception("Error creating namespace:", e.output)
 
@@ -207,7 +225,11 @@ def delete_namespace(namespaces):
     """
     try:
         for namespace in namespaces:
-            subprocess.run(["ip", "netns", "del", namespace], capture_output=True)
+            result = subprocess.run(
+                ["ip", "netns", "del", namespace], capture_output=True
+            )
+            if result.returncode != 0:
+                raise Exception(f"Error while deleting namespace {namespace}")
     except subprocess.CalledProcessError as e:
         raise Exception("Error deleting namespace:", e.output)