fix(test): do not pass network config to CPU template helper

CPU template helper tool uses a microVM configuration we pass to it to
launch a VM and get it's CPU config. Our integration test that drives
that needs to configure the microVM with a network interface so that it
can SSH into it and run commands. However, when we pass to helper tool
a configuration that includes networking, we run into a race-condition
with creating/configuring a TAP device.

This commit passes a microVM configuration without a network interface
to the helper tool to avoid the race.

Signed-off-by: Babis Chalios <[email protected]>

Author: bchalios

tests/integration_tests/functional/test_cpu_template_helper.py

@@ -285,14 +285,21 @@ def test_cpu_config_dump_vs_actual(
     microvm = microvm_factory.build(guest_kernel, rootfs)
     microvm.spawn()
     microvm.basic_config()
-    microvm.add_net_iface()
     vm_config_path = save_vm_config(microvm, tmp_path)
 
     # Dump CPU config with the helper tool.
     cpu_config_path = tmp_path / "cpu_config.json"
     cpu_template_helper.template_dump(vm_config_path, cpu_config_path)
     dump_cpu_config = build_cpu_config_dict(cpu_config_path)
 
+    # Add the network interface after we dump the CPU config via
+    # the CPU template helper tool. The tool creates a microVM with
+    # the config we pass it. When we pass it network configuration, we
+    # run in some sort of race condition with TAP device creation.
+    # CPU template helper tool doesn't need the network device configuration
+    # so, add it to `microvm` after we have dumped the CPU config.
+    microvm.add_net_iface()
+
     # Retrieve actual CPU config from guest
     microvm.start()
     actual_cpu_config = {