This introduces a functional test of vhost-user-bridge. The test runs vhost-user-bridge and launches a guest VM that connects to the internet through it. The test succeeds if and only if an attempt to connect to a hard-coded well-known URL succeeds.
Signed-off-by: Yodel Eldar <[email protected]> --- This patch introduces a functional test of vhost-user-bridge by automating the testing described in its initial commit, 8e3b0cbb72, with adjustments like using hubports (formerly the vlan parameter) and memfd for the memory backend; hugepages are also omitted to avoid requiring root privileges on the host. The test configures networking within the guest by invoking udhcpc, then makes an http request via wget to a well-known URL, example.org, that has a low risk of requiring https for connections (a limitation of the the test). An assert on the retcode of wget determines success/failure. Please let me know if there are objections to the use of wget's retcode as the test's condition; determining wget success through its output is straightforward ("remote file exists"), but out of concern of some unknown failure message (besides "bad address") locking up the test, I've resorted to checking the retcode instead; perhaps, this violates some convention? Also, I figured checking for memfd support on the host was unnecessary in 2026 for the intended users of the test, but perhaps not? The guest's kernel contains an integrated initramfs and was built with buildroot; an attempt to ensure bit-for-bit reproducibility was made by building it via Containerfile based on a snapshot container image and use of the BR2_REPRODUCIBLE option of buildroot, but the latter feature is "experimental," so future builds may differ slightly (though the image in the repo will be left untouched). The image and associated build files are hosted on my personal account here: https://github.com/yodel/vhost-user-bridge-test and will continue to be well into the future, but if there's some other preferred location for the asset, please let me know? Lastly, special thanks to Cédric for inspiring me to write the test in "<[email protected]>". Thanks, Yodel .../x86_64/test_vhost_user_bridge.py | 124 ++++++++++++++++++ 1 file changed, 124 insertions(+) create mode 100755 tests/functional/x86_64/test_vhost_user_bridge.py diff --git a/tests/functional/x86_64/test_vhost_user_bridge.py b/tests/functional/x86_64/test_vhost_user_bridge.py new file mode 100755 index 0000000000..61afdbceec --- /dev/null +++ b/tests/functional/x86_64/test_vhost_user_bridge.py @@ -0,0 +1,124 @@ +#!/usr/bin/env python3 +# +# Copyright (c) 2025 Software Freedom Conservancy, Inc. +# +# Author: Yodel Eldar <[email protected]> +# +# SPDX-License-Identifier: GPL-2.0-or-later +""" +Test vhost-user-bridge (vubr) functionality: + + 1) Run vhost-user-bridge on the host. + 2) Launch a guest VM: + a) Instantiate a unix domain socket to the vubr-created path + b) Instantiate a vhost-user net backend on top of that socket + c) Expose vhost-user with a virtio-net-pci interface + d) Instantiate UDP socket and user-mode net backends + e) Hub the UDP and user-mode backends + 3) Run udhcpc in the guest to auto-configure networking. + 4) Run wget in the guest and check its retcode to test internet connectivity + +The test fails if wget returns 1 and succeeds on 0. +""" + +import os +import subprocess +from qemu_test import Asset, QemuSystemTest, which +from qemu_test import exec_command_and_wait_for_pattern +from qemu_test import is_readable_executable_file +from qemu_test import wait_for_console_pattern +from qemu_test.ports import Ports + +class VhostUserBridge(QemuSystemTest): + + ASSET_KERNEL_INITRAMFS = Asset( + "https://github.com/yodel/vhost-user-bridge-test/raw/refs/heads/main/bzImage";, + "3790bf35e4ddfe062425bca45e923df5a5ee4de44e456d6b00cf47f04991d549") + + def configure_vm(self, ud_socket_path, lport, rport): + kernel_path = self.ASSET_KERNEL_INITRAMFS.fetch() + + self.require_accelerator("kvm") + self.require_netdev("vhost-user") + self.require_netdev("socket") + self.require_netdev("hubport") + self.require_netdev("user") + self.require_device("virtio-net-pci") + self.set_machine("q35") + self.vm.set_console() + self.vm.add_args( + "-cpu", "host", + "-accel", "kvm", + "-kernel", kernel_path, + "-append", "console=ttyS0", + "-smp", "2", + "-m", "128M", + "-object", "memory-backend-memfd,id=mem0," + "size=128M,share=on,prealloc=on", + "-numa", "node,memdev=mem0", + "-chardev", f"socket,id=char0,path={ud_socket_path}", + "-netdev", "vhost-user,id=vhost0,chardev=char0,vhostforce=on", + "-device", "virtio-net-pci,netdev=vhost0", + "-netdev", f"socket,id=udp0,udp=localhost:{lport}," + f"localaddr=localhost:{rport}", + "-netdev", "hubport,id=hub0,hubid=0,netdev=udp0", + "-netdev", "user,id=user0", + "-netdev", "hubport,id=hub1,hubid=0,netdev=user0" + ) + + def assemble_vubr_args(self, vubr_path, ud_socket_path, lport, rport): + vubr_args = [] + + if (stdbuf_path := which("stdbuf")) is None: + self.log.info("Could not find stdbuf: vhost-user-bridge " + "log lines may appear out of order") + else: + vubr_args += [stdbuf_path, "-o0", "-e0"] + + vubr_args += [vubr_path, "-u", f"{ud_socket_path}", + "-l", f"127.0.0.1:{lport}", "-r", f"127.0.0.1:{rport}"] + + return vubr_args + + def test_vhost_user_bridge(self): + prompt = "~ # " + + vubr_path = self.build_file("tests", "vhost-user-bridge") + if is_readable_executable_file(vubr_path) is None: + self.skipTest("Could not find a readable and executable " + "vhost-user-bridge") + + with Ports() as ports: + sock_dir = self.socket_dir() + ud_socket_path = os.path.join(sock_dir.name, "vubr-test.sock") + lport, rport = ports.find_free_ports(2) + + self.configure_vm(ud_socket_path, lport, rport) + + vubr_log_path = self.log_file("vhost-user-bridge.log") + self.log.info("For the vhost-user-bridge application log," + f" see: {vubr_log_path}") + + vubr_args = self.assemble_vubr_args(vubr_path, ud_socket_path, + lport, rport) + + with open(vubr_log_path, "w") as vubr_log, \ + subprocess.Popen(vubr_args, stdin=subprocess.DEVNULL, + stdout=vubr_log, stderr=subprocess.STDOUT): + self.vm.launch() + + wait_for_console_pattern(self, prompt) + exec_command_and_wait_for_pattern(self, "udhcpc -nt 1", prompt) + exec_command_and_wait_for_pattern(self, + "wget -qT 2 --spider example.org", prompt) + + try: + exec_command_and_wait_for_pattern(self, "echo $?", "0", "1") + except AssertionError: + self.log.error("Unable to confirm internet connectivity") + raise + finally: + self.vm.shutdown() + +if __name__ == '__main__': + QemuSystemTest.main() -- 2.52.0
