Re: [PATCH v5 1/4] avocado_qemu: Fix KNOWN_DISTROS map into the LinuxDistro class

[Cleber Rosa]

On 7/6/21 9:17 AM, Eric Auger wrote:
> From: Willian Rampazzo <willianr@redhat.com>
>
> As the KNOWN_DISTROS grows, more loosely methods will be created in
> the avocado_qemu/__init__.py file.
>
> Let's refactor the code so that KNOWN_DISTROS and related methods are
> packaged in a class
>
> Signed-off-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> ---
>   tests/acceptance/avocado_qemu/__init__.py | 74 +++++++++++++----------
>   1 file changed, 42 insertions(+), 32 deletions(-)
>
> diff --git a/tests/acceptance/avocado_qemu/__init__.py 
> b/tests/acceptance/avocado_qemu/__init__.py
> index 81ac90bebb..af93cd63ea 100644
> --- a/tests/acceptance/avocado_qemu/__init__.py
> +++ b/tests/acceptance/avocado_qemu/__init__.py
> @@ -299,29 +299,43 @@ def ssh_command(self, command):
>                            f'Guest command failed: {command}')
>           return stdout_lines, stderr_lines
>   
> +class LinuxDistro:
> +    """Represents a Linux distribution
>   


I definitely like the idea.


> -#: A collection of known distros and their respective image checksum
> -KNOWN_DISTROS = {
> -    'fedora': {
> -        '31': {
> -            'x86_64':
> -            {'checksum': 
> 'e3c1b309d9203604922d6e255c2c5d098a309c2d46215d8fc026954f3c5c27a0'},
> -            'aarch64':
> -            {'checksum': 
> '1e18d9c0cf734940c4b5d5ec592facaed2af0ad0329383d5639c997fdf16fe49'},
> -            'ppc64':
> -            {'checksum': 
> '7c3528b85a3df4b2306e892199a9e1e43f991c506f2cc390dc4efa2026ad2f58'},
> -            's390x':
> -            {'checksum': 
> '4caaab5a434fd4d1079149a072fdc7891e354f834d355069ca982fdcaf5a122d'},
> +    Holds information of known distros.
> +    """
> +    #: A collection of known distros and their respective image checksum
> +    KNOWN_DISTROS = {
> +        'fedora': {
> +            '31': {
> +                'x86_64':
> +                {'checksum': 
> 'e3c1b309d9203604922d6e255c2c5d098a309c2d46215d8fc026954f3c5c27a0'},
> +                'ppc64':
> +                {'checksum': 
> '7c3528b85a3df4b2306e892199a9e1e43f991c506f2cc390dc4efa2026ad2f58'},
> +                's390x':
> +                {'checksum': 
> '4caaab5a434fd4d1079149a072fdc7891e354f834d355069ca982fdcaf5a122d'},
>               }
>           }
>       }
>   
> +    def __init__(self, name, version, arch):
> +        self.name = name
> +        self.version = version
> +        self.arch = arch


This looks a lot like 
https://github.com/avocado-framework/avocado/blob/f0996dafefa412c77c221c2d1a6fafdcba1c97b7/avocado/utils/distro.py#L34 
, although admittedly, their goals are very different.


As a next step, in the future, I'd consider separating the data from the 
actual class and having it the LinuxDistro instances, helped by a 
registry.  Something like:


class LinuxDistroRegistry:

   def __init__(self):
      self.distros = set()

   def register(self, linux_distro):

      self.distros.add(linux_distro)

   def query(self, **kwargs):

      ...


registry = LinuxDistroRegistry()

registry.register(LinuxDistro('fedora', '31', 'x86_64', 'deadbeefdeadbeef'))

registry.register(LinuxDistro('fedora', '31', 'aarch64', 
'beefdeadbeefdead'))

checksum = registry.query(name='fedora', version='31', 
arch='x86_64').checksum


> +        try:
> +            self._info = self.KNOWN_DISTROS.get(name).get(version).get(arch)


The `AttributeError` that could be caught at the removed 
`get_known_distro_checksum()` function, could come from any of the 
`.get()`s returning `None`, which in turn would not have a `.get()` 
attribute.

But now, if there's a "name", then a "version", but no "arch" entry, 
this line will set `self._info` to `None`.  This is manifested if you 
try to run a test that tries to find an aarch64 distro, such as:

./tests/venv/bin/avocado run 
tests/acceptance/boot_linux.py:BootLinuxAarch64.test_virt_tcg_gicv2


It will result in:


20:38:18 ERROR| Reproduced traceback from: 
/var/lib/users/cleber/build/qemu/tests/venv/lib64/python3.9/site-packages/avocado/core/test.py:756
20:38:18 ERROR| Traceback (most recent call last):
20:38:18 ERROR|   File 
"/var/lib/users/cleber/build/qemu/tests/acceptance/avocado_qemu/__init__.py", 
line 426, in download_boot
20:38:18 ERROR|     checksum=self.distro.checksum,
20:38:18 ERROR|   File 
"/var/lib/users/cleber/build/qemu/tests/acceptance/avocado_qemu/__init__.py", 
line 334, in checksum
20:38:18 ERROR|     return self._info.get('checksum', None)
20:38:18 ERROR| AttributeError: 'NoneType' object has no attribute 'get'
20:38:18 ERROR|
20:38:18 ERROR| During handling of the above exception, another 
exception occurred:
20:38:18 ERROR|
20:38:18 ERROR| Traceback (most recent call last):
20:38:18 ERROR|   File 
"/var/lib/users/cleber/build/qemu/tests/acceptance/avocado_qemu/__init__.py", 
line 387, in setUp
20:38:18 ERROR|     self.set_up_boot()
20:38:18 ERROR|   File 
"/var/lib/users/cleber/build/qemu/tests/acceptance/avocado_qemu/__init__.py", 
line 455, in set_up_boot
20:38:18 ERROR|     path = self.download_boot()
20:38:18 ERROR|   File 
"/var/lib/users/cleber/build/qemu/tests/acceptance/avocado_qemu/__init__.py", 
line 431, in download_boot
20:38:18 ERROR|     self.cancel('Failed to download/prepare boot image')
20:38:18 ERROR|   File 
"/var/lib/users/cleber/build/qemu/tests/venv/lib64/python3.9/site-packages/avocado/core/test.py", 
line 988, in cancel
20:38:18 ERROR|     raise exceptions.TestCancel(message)
20:38:18 ERROR| avocado.core.exceptions.TestCancel: Failed to 
download/prepare boot image


Cheers,

- Cleber.