On Tue, Aug 15, 2017 at 10:57 AM, Markus Armbruster <arm...@redhat.com> wrote:
> Amador Pahim <apa...@redhat.com> writes:
>
>> When launching a VM, if an exception happens and the VM is not
>> initiated, it is useful to see the qemu command line that was executed
>> and the output of that command.
>>
>> Before this patch:
>>
>> >>> import qemu
>> >>> vm = qemu.QEMUMachine('qemu-system-aarch64', debug=True)
>> >>> vm.launch()
>> Traceback (most recent call last):
>> File "<stdin>", line 1, in <module>
>> File "qemu.py", line 175, in launch
>> self._launch()
>> File "qemu.py", line 189, in _launch
>> self._post_launch()
>> File "qemu.py", line 154, in _post_launch
>> self._qmp.accept()
>> File "qmp/qmp.py", line 145, in accept
>> self.__sock, _ = self.__sock.accept()
>> File "/usr/lib64/python2.7/socket.py", line 206, in accept
>> sock, addr = self._sock.accept()
>> socket.timeout: timed out
>> >>>
>>
>> After this patch:
>>
>> >>> import qemu
>> >>> vm = qemu.QEMUMachine('qemu-system-aarch64', debug=True)
>> >>> vm.launch()
>> DEBUG:qemu:Error launching VM. Command: 'qemu-system-aarch64
>> -chardev socket,id=mon,path=/var/tmp/qemu-5298-monitor.sock
>> -mon chardev=mon,mode=control -display none -vga none'.
>> Output: 'qemu-system-aarch64: No machine specified, and there
>> is no default\nUse -machine help to list supported machines\n'.
>> Traceback (most recent call last):
>> File "<stdin>", line 1, in <module>
>> File "qemu.py", line 175, in launch
>> self._launch()
>> File "qemu.py", line 189, in _launch
>> self._post_launch()
>> File "qemu.py", line 154, in _post_launch
>> self._qmp.accept()
>> File "qmp/qmp.py", line 145, in accept
>> self.__sock, _ = self.__sock.accept()
>> File "/usr/lib64/python2.7/socket.py", line 206, in accept
>> sock, addr = self._sock.accept()
>> socket.timeout: timed out
>> >>>
>>
>> Signed-off-by: Amador Pahim <apa...@redhat.com>
>> ---
>> scripts/qemu.py | 12 +++++++++++-
>> 1 file changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/scripts/qemu.py b/scripts/qemu.py
>> index e9a3a96d13..43fd0b072c 100644
>> --- a/scripts/qemu.py
>> +++ b/scripts/qemu.py
>> @@ -158,7 +158,10 @@ class QEMUMachine(object):
>> self._remove_if_exists(self._created_files.pop())
>>
>> def launch(self):
>> - '''Launch the VM and establish a QMP connection'''
>> + '''
>> + Try to launch the VM and make sure we cleanup and expose the
>> + command line/output in case of exception.
>> + '''
>>
>> if self.is_running():
>> raise QEMULaunchError('VM already running.')
>> @@ -169,6 +172,7 @@ class QEMUMachine(object):
>> 'before launching again.')
>>
>> try:
>> + self._iolog = None
>> self._qemu_full_args = None
>> self._qemu_full_args = (self._wrapper + [self._binary] +
>> self._base_args() + self._args)
>> @@ -176,9 +180,15 @@ class QEMUMachine(object):
>> self._pending_shutdown = True
>> except:
>> self.shutdown()
>> + LOG.debug('Error launching VM.%s%s',
>> + ' Command: %r.' % ' '.join(self._qemu_full_args)
>> + if self._qemu_full_args else '',
>> + ' Output: %r.' % self._iolog
>> + if self._iolog else '')
>
> This nested interpolation is too ugly to live :)
I find it beautiful :)
Killing it anyway.
>
> Nesting is easy to avoid:
>
> LOG.debug('Error launching VM\n. ' Command: %r. Output: %r.'
> % (' '.join(self._qemu_full_args)
> if self._qemu_full_args else '',
> self._iolog
> if self._iolog else ''))
In this case we will have the strings "Command: " and "Output:" even
with no content to expose.
>
> Why %r and not %s?
It's a matter of preference. I tend to avoid allowing messages to
break the log line. Anyway, I'm improving this.
>
> Are you sure '\n' is appropriate in the argument of LOG.debug()?
>
> Why cram everything into a single LOG.debug()?
>
> LOG.debug('Error launching VM')
> LOG.debug('Command: %s' % (' '.join(self._qemu_full_args)
> if self._qemu_full_args else ''))
> LOG.debug('Output: %s' % self._iolog if self._iolog else ''))
Sure, I'm ok with both ways.
>
>> raise
>>
>> def _launch(self):
>> + '''Launch the VM and establish a QMP connection.'''
>> self._pre_launch()
>> devnull = open(os.path.devnull, 'rb')
>> self._popen = subprocess.Popen(self._qemu_full_args,
