Commit d4d75501 authored by Raito Bezarius's avatar Raito Bezarius
Browse files

nixos/test-driver: provide a global timeout 

Since the debut of the test-driver, we didn't obtain
a race timer with the test execution to ensure that tests doesn't run beyond
a certain amount of time.

This is particularly important when you are running into hanging tests
which cannot be detected by current facilities (requires more pvpanic wiring up, QMP
API stuff, etc.).

Two easy examples:

- Some QEMU tests may get stuck in some situation and run for more than 24 hours → we default to 1 hour max.
- Some QEMU tests may panic in the wrong place, e.g. UEFI firmware or worse → end users can set a "reasonable" amount of time

And then, we should let the retry logic retest them until they succeed and adjust
their global timeouts.

Of course, this does not help with the fact that the timeout may need to be
a function of the actual busyness of the machine running the tests.
This is only one step towards increased reliability.
parent 3244b1ea

nixos/lib/test-driver/test_driver/__init__.py

+9 −0
Original line number Diff line number Diff line
@@ -76,6 +76,14 @@ def main() -> None: 
        nargs="*",

        help="vlans to span by the driver",

    )

    arg_parser.add_argument(

        "--global-timeout",

        type=int,

        metavar="GLOBAL_TIMEOUT",

        action=EnvDefault,

        envvar="globalTimeout",

        help="Timeout in seconds for the whole test",

    )

    arg_parser.add_argument(

        "-o",

        "--output_directory",
@@ -103,6 +111,7 @@ def main() -> None: 
        args.testscript.read_text(),

        args.output_directory.resolve(),

        args.keep_vm_state,

        args.global_timeout,

    ) as driver:

        if args.interactive:

            history_dir = os.getcwd()

nixos/lib/test-driver/test_driver/driver.py

+25 −0
Original line number Diff line number Diff line 
import os

import re

import signal

import tempfile

import threading

from contextlib import contextmanager

from pathlib import Path

from typing import Any, Callable, ContextManager, Dict, Iterator, List, Optional, Union
@@ -41,6 +43,8 @@ class Driver: 
    vlans: List[VLan]

    machines: List[Machine]

    polling_conditions: List[PollingCondition]

    global_timeout: int

    race_timer: threading.Timer



    def __init__(

        self,
@@ -49,9 +53,12 @@ class Driver: 
        tests: str,

        out_dir: Path,

        keep_vm_state: bool = False,

        global_timeout: int = 24 * 60 * 60 * 7,

    ):

        self.tests = tests

        self.out_dir = out_dir

        self.global_timeout = global_timeout

        self.race_timer = threading.Timer(global_timeout, self.terminate_test)



        tmp_dir = get_tmp_dir()
@@ -82,6 +89,7 @@ class Driver: 


    def __exit__(self, *_: Any) -> None:

        with rootlog.nested("cleanup"):

            self.race_timer.cancel()

            for machine in self.machines:

                machine.release()
@@ -144,6 +152,10 @@ class Driver: 


    def run_tests(self) -> None:

        """Run the test script (for non-interactive test runs)"""

        rootlog.info(

            f"Test will time out and terminate in {self.global_timeout} seconds"

        )

        self.race_timer.start()

        self.test_script()

        # TODO: Collect coverage data

        for machine in self.machines:
@@ -161,6 +173,19 @@ class Driver: 
        with rootlog.nested("wait for all VMs to finish"):

            for machine in self.machines:

                machine.wait_for_shutdown()

            self.race_timer.cancel()



    def terminate_test(self) -> None:

        # This will be usually running in another thread than

        # the thread actually executing the test script.

        with rootlog.nested("timeout reached; test terminating..."):

            for machine in self.machines:

                machine.release()

            # As we cannot `sys.exit` from another thread

            # We can at least force the main thread to get SIGTERM'ed.

            # This will prevent any user who caught all the exceptions

            # to swallow them and prevent itself from terminating.

            os.kill(os.getpid(), signal.SIGTERM)



    def create_machine(self, args: Dict[str, Any]) -> Machine:

        tmp_dir = get_tmp_dir()

nixos/lib/testing-python.nix

+1 −0
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ rec { 
    , nodes ? {}

    , testScript

    , enableOCR ? false

    , globalTimeout ? (60 * 60)

    , name ? "unnamed"

    , skipTypeCheck ? false

      # Skip linting (mainly intended for faster dev cycles)

nixos/lib/testing/driver.nix

+13 −0
Original line number Diff line number Diff line
@@ -94,6 +94,7 @@ let 
        wrapProgram $out/bin/nixos-test-driver \

          --set startScripts "''${vmStartScripts[*]}" \

          --set testScript "$out/test-script" \

          --set globalTimeout "${toString config.globalTimeout}" \

          --set vlans '${toString vlans}' \

          ${lib.escapeShellArgs (lib.concatMap (arg: ["--add-flags" arg]) config.extraDriverArgs)}

      '';
@@ -123,6 +124,18 @@ in 
      defaultText = "hostPkgs.qemu_test";

    };



    globalTimeout = mkOption {

      description = mdDoc ''

        A global timeout for the complete test, expressed in seconds.

        Beyond that timeout, every resource will be killed and released and the test will fail.



        By default, we use a 1 hour timeout.

      '';

      type = types.int;

      default = 60 * 60;

      example = 10 * 60;

    };



    enableOCR = mkOption {

      description = mdDoc ''

        Whether to enable Optical Character Recognition functionality for