Add ssh backdoor to VM tests infrastructure.

Thanks to @dezgeg for prototype implementation, I've
cleaned it up and added documentation.
This commit is contained in:
Tuomas Tynkkynen 2018-09-26 22:17:14 +03:00 committed by Domen Kožar
parent f0e4b31eb2
commit d6e3db44cf
4 changed files with 43 additions and 3 deletions

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@ -0,0 +1,36 @@
<section xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:xi="http://www.w3.org/2001/XInclude"
version="5.0"
xml:id="sec-debugging-nixos-tests">
<title>Debugging NixOS tests</title>
<para>
Tests may fail and infrastructure offers access to inspect machine state.
</para>
<para>
To prevent test from stopping and cleaning up, insert a sleep command:
</para>
<programlisting>
$machine->succeed("sleep 84000");
</programlisting>
<para>
As soon as machine starts run as root:
</para>
<programlisting>
nix-shell -p socat --run "socat STDIO,raw,echo=0,escape=0x11 UNIX:/tmp/nix-build-vm-test-run-*.drv-0/vm-state-machine/backdoor"
</programlisting>
<para>
You may need to find the correct path, replacing <literal>/tmp</literal>, <literal>*</literal> or <literal>machine</literal>.
</para>
<para>
Press "enter" to open up console and login as "root". After you're done, press "ctrl-q" to exit the console.
</para>
</section>

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@ -16,4 +16,5 @@ xlink:href="https://github.com/NixOS/nixpkgs/tree/master/nixos/tests">nixos/test
<xi:include href="writing-nixos-tests.xml" />
<xi:include href="running-nixos-tests.xml" />
<xi:include href="running-nixos-tests-interactively.xml" />
<xi:include href="debugging-nixos-tests.xml" />
</chapter>

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@ -155,8 +155,10 @@ sub start {
$ENV{USE_TMPDIR} = 1;
$ENV{QEMU_OPTS} =
($self->{allowReboot} ? "" : "-no-reboot ") .
"-monitor unix:./monitor -chardev socket,id=shell,path=./shell " .
"-device virtio-serial -device virtconsole,chardev=shell " .
"-monitor unix:./monitor " .
"-chardev socket,id=shell,path=./shell -device virtio-serial -device virtconsole,chardev=shell " .
# socket backdoor, see "Debugging NixOS tests" section in NixOS manual
"-chardev socket,id=backdoor,path=./backdoor,server,nowait -device virtio-serial -device virtconsole,chardev=backdoor " .
"-device virtio-rng-pci " .
($showGraphics ? "-serial stdio" : "-nographic") . " " . ($ENV{QEMU_OPTS} || "");
chdir $self->{stateDir} or die;

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@ -55,7 +55,8 @@ with import ../../lib/qemu-flags.nix { inherit pkgs; };
systemd.services."serial-getty@hvc0".enable = false;
# Only use a serial console, no TTY.
virtualisation.qemu.consoles = [ qemuSerialDevice ];
# hvc1: socket backdoor, see "Debugging NixOS tests" section in NixOS manual
virtualisation.qemu.consoles = [ "hvc1" qemuSerialDevice ];
boot.initrd.preDeviceCommands =
''