[Avocado-devel] nettype setting in test cfg

[Lukáš Doktor]

Dne 14.8.2017 v 16:50 Wei Huang napsal(a):
> 
> 
> On 08/14/2017 06:13 AM, Lukáš Doktor wrote:
>> Dne 11.8.2017 v 19:20 Wei Huang napsal(a):
>>> Hi,
>>>
>> Hello Wei,
>>
>>> I have questions regarding setting vt.qemu properties in test cfg file.
>>> In this case, I want to specify a default nettype="bridge" for mytest.
>>
>> Let's clarify few points first. I assume you are talking about test-related cfg, not the `--vt-config` one, right?
> 
> Right, it is a test cfg file.
> 
>>
>>>
>>> 1) If I want to set a nettype for mytest.py, should I just add "nettype
>>> = 'bridge'" inside mytest.cfg file? Does mytest.py needs to read this
>>> property using "params.get()" to populate this property to final test run?
>>>
>>
>> Test configuration is not suppose to change the `nettype`. The `nettype` is a global network type, which is used by all tests and one should be able to switch between them via config/cmdline. If your test only works with certain nettype, you should use `only bridge` or `only user, bridge` or whatever suites your situation, that way the test will not run without given nettype.
>>
>> On the other hand when your test defines multiple nics and you know for some of them you require bridge, you can change per-vm nettype by using `nettype_$vmname`, which always overrides the default. Anyway you should never do this for the main VM as that would result in the test being executed (and named) for example as `qemu_kvm_jeos_quick.user.default_bios.no_virtio_rng.(image_backend=filesystem).no_9p_export.smallpages.no_pci_assignable.qcow2.virtio_scsi.smp2.virtio_net.Linux.JeOS.25.x86_64.i440fx.Fedora.m25.u0.Host_arch_x86_64.(subtest=io-github-autotest-qemu).(subtest=boot)`, which implies `user` network was used, but in fact `bridge` would be used. This would be misleading.
>>
>> Another why you shouldn't do this is that running suite of tests on `bridge` and `user` would result in the same test being ran twice with the very same configuration.
>>
>> So please use `only bridge` if your test requires bridge, which means it'd not be found when running with `user` and it'd only run in suites where `bridge` is used. (also don't forget to re-run `vt-bootstrap` after any change to test's cfg files to propagate into subtests.cfg)
> 
> I will use this approach then. I will add a warning to mytest.py file
> when user-mode net is detected (like migration_with_dst_problem.py does).
> 
In theory it should never happen, but it is very helpful to add such messages as people can always force it and wonder why is it failing (eg. by using bridge and `--vt-extra-params nettype=user`).

Kind regards,
Lukáš

>>
>>> 2) From what I have seen, the setting of nettype in
>>> /etc/avocado/conf.d/vt.cfg seems to override what I set in mytest.cfg.
>>> Does it mean the settings in vt.cfg has a higher precedence over
>>> settings in individual test configure files?
>>>
>>
>> Exactly. First cfgs are processed, then additional filters/tweaks are done. You can see it in `avocado_vt/options.py` around lines 475.
>>
>> PS: Note that currently there is a pending PR to change the default for `--vt-type qemu` to `bridge` when running as root and to keep it `user` when running as non-root. This might give you better experience.
> 
> I saw this warning message in current avocado. I agree this PR will be
> helpful.
> 
>>
>>> Thanks,
>>> -Wei
>>>
>>
>>


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