Re: [PATCH v2 03/10] Python: add utility function for retrieving port redirection

[Cleber Rosa]

On Wed, Mar 24, 2021 at 05:35:07PM -0300, Willian Rampazzo wrote:
> On Tue, Mar 23, 2021 at 7:16 PM Cleber Rosa <crosa@redhat.com> wrote:
> >
> > Slightly different versions for the same utility code are currently
> > present on different locations.  This unifies them all, giving
> > preference to the version from virtiofs_submounts.py, because of the
> > last tweaks added to it.
> >
> > While at it, this adds a "qemu.utils" module to host the utility
> > function and a test.
> >
> > Signed-off-by: Cleber Rosa <crosa@redhat.com>
> > Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
> > ---
> >  python/qemu/utils.py                     | 35 ++++++++++++++++++++++++
> >  tests/acceptance/info_usernet.py         | 29 ++++++++++++++++++++
> >  tests/acceptance/linux_ssh_mips_malta.py | 16 +++++------
> >  tests/acceptance/virtiofs_submounts.py   | 21 ++++----------
> >  tests/vm/basevm.py                       |  7 ++---
> >  5 files changed, 78 insertions(+), 30 deletions(-)
> >  create mode 100644 python/qemu/utils.py
> >  create mode 100644 tests/acceptance/info_usernet.py
> >
> > diff --git a/python/qemu/utils.py b/python/qemu/utils.py
> > new file mode 100644
> > index 0000000000..89a246ab30
> > --- /dev/null
> > +++ b/python/qemu/utils.py
> > @@ -0,0 +1,35 @@
> > +"""
> > +QEMU utility library
> > +
> > +This offers miscellaneous utility functions, which may not be easily
> > +distinguishable or numerous to be in their own module.
> > +"""
> > +
> > +# Copyright (C) 2021 Red Hat Inc.
> > +#
> > +# Authors:
> > +#  Cleber Rosa <crosa@redhat.com>
> > +#
> > +# This work is licensed under the terms of the GNU GPL, version 2.  See
> > +# the COPYING file in the top-level directory.
> > +#
> > +
> > +import re
> > +from typing import Optional
> > +
> > +
> > +def get_info_usernet_hostfwd_port(info_usernet_output: str) -> 
> > Optional[int]:
> > +    """
> > +    Returns the port given to the hostfwd parameter via info usernet
> > +
> > +    :param info_usernet_output: output generated by hmp command "info 
> > usernet"
> > +    :param info_usernet_output: str
> > +    :return: the port number allocated by the hostfwd option
> > +    :rtype: int
> > +    """
> > +    for line in info_usernet_output.split('\r\n'):
> > +        regex = r'TCP.HOST_FORWARD.*127\.0\.0\.1\s+(\d+)\s+10\.'
> > +        match = re.search(regex, line)
> > +        if match is not None:
> > +            return int(match[1])
> > +    return None
> > diff --git a/tests/acceptance/info_usernet.py 
> > b/tests/acceptance/info_usernet.py
> > new file mode 100644
> > index 0000000000..9c1fd903a0
> > --- /dev/null
> > +++ b/tests/acceptance/info_usernet.py
> > @@ -0,0 +1,29 @@
> > +# Test for the hmp command "info usernet"
> > +#
> > +# Copyright (c) 2021 Red Hat, Inc.
> > +#
> > +# Author:
> > +#  Cleber Rosa <crosa@redhat.com>
> > +#
> > +# This work is licensed under the terms of the GNU GPL, version 2 or
> > +# later.  See the COPYING file in the top-level directory.
> > +
> > +from avocado_qemu import Test
> > +
> > +from qemu.utils import get_info_usernet_hostfwd_port
> > +
> > +
> > +class InfoUsernet(Test):
> > +
> > +    def test_hostfwd(self):
> > +        self.vm.add_args('-netdev', 
> > 'user,id=vnet,hostfwd=:127.0.0.1:0-:22')
> > +        self.vm.launch()
> > +        res = self.vm.command('human-monitor-command',
> > +                              command_line='info usernet')
> 
> This pattern is repeated every time a test needs to call
> get_info_usernet_hostfwd_port. Do you see any downside on moving this
> line inside the function and passing self.vm as an argument? This
> would abstract the need to run info usernet before calling the
> function.
> 

My original plan was to follow this up with a utility in QEMUMachine
itself (because that is the vm).  It can still be done, but:

 * I don't expect *tests* to be calling this often, rather a base
   class for tests;

 * I'm avoiding changing QEMUMachine too much, given it's a more
   generic class and used by other tests (iotests, vm, etc).

Hopefully when we have a better laid out structure for adding tests to
QEMUMachine itself, it'll be confortable to change it more
drastically.

> > +        port = get_info_usernet_hostfwd_port(res)
> > +        self.assertIsNotNone(port,
> > +                             ('"info usernet" output content does not seem 
> > to '
> > +                              'contain the redirected port'))
> > +        self.assertGreater(port, 0,
> > +                           ('Found a redirected port that is not greater 
> > than'
> > +                            ' zero'))
> > diff --git a/tests/acceptance/linux_ssh_mips_malta.py 
> > b/tests/acceptance/linux_ssh_mips_malta.py
> > index 6dbd02d49d..052008f02d 100644
> > --- a/tests/acceptance/linux_ssh_mips_malta.py
> > +++ b/tests/acceptance/linux_ssh_mips_malta.py
> > @@ -18,6 +18,8 @@
> >  from avocado.utils import archive
> >  from avocado.utils import ssh
> >
> > +from qemu.utils import get_info_usernet_hostfwd_port
> > +
> >
> >  class LinuxSSH(Test):
> >
> > @@ -70,18 +72,14 @@ def get_kernel_info(self, endianess, wordsize):
> >      def setUp(self):
> >          super(LinuxSSH, self).setUp()
> >
> > -    def get_portfwd(self):
> > +    def ssh_connect(self, username, password):
> > +        self.ssh_logger = logging.getLogger('ssh')
> >          res = self.vm.command('human-monitor-command',
> >                                command_line='info usernet')
> > -        line = res.split('\r\n')[2]
> > -        port = re.split(r'.*TCP.HOST_FORWARD.*127\.0\.0\.1 (\d+)\s+10\..*',
> > -                        line)[1]
> > +        port = get_info_usernet_hostfwd_port(res)
> > +        if not port:
> > +            self.cancel("Failed to retrieve SSH port")
> >          self.log.debug("sshd listening on port:" + port)
> > -        return port
> > -
> > -    def ssh_connect(self, username, password):
> > -        self.ssh_logger = logging.getLogger('ssh')
> > -        port = self.get_portfwd()
> >          self.ssh_session = ssh.Session(self.VM_IP, port=int(port),
> >                                         user=username, password=password)
> >          for i in range(10):
> > diff --git a/tests/acceptance/virtiofs_submounts.py 
> > b/tests/acceptance/virtiofs_submounts.py
> > index ca64b76301..57a7047342 100644
> > --- a/tests/acceptance/virtiofs_submounts.py
> > +++ b/tests/acceptance/virtiofs_submounts.py
> > @@ -9,6 +9,8 @@
> >  from avocado_qemu import wait_for_console_pattern
> >  from avocado.utils import ssh
> >
> > +from qemu.utils import get_info_usernet_hostfwd_port
> > +
> >
> >  def run_cmd(args):
> >      subp = subprocess.Popen(args,
> > @@ -73,27 +75,14 @@ class VirtiofsSubmountsTest(LinuxTest):
> >      :avocado: tags=accel:kvm
> >      """
> >
> > -    def get_portfwd(self):
> > -        port = None
> > -
> > +    def ssh_connect(self, username, keyfile):
> > +        self.ssh_logger = logging.getLogger('ssh')
> >          res = self.vm.command('human-monitor-command',
> >                                command_line='info usernet')
> > -        for line in res.split('\r\n'):
> > -            match = \
> > -                re.search(r'TCP.HOST_FORWARD.*127\.0\.0\.1\s+(\d+)\s+10\.',
> > -                          line)
> > -            if match is not None:
> > -                port = int(match[1])
> > -                break
> > -
> > +        port = get_info_usernet_hostfwd_port(res)
> >          self.assertIsNotNone(port)
> >          self.assertGreater(port, 0)
> >          self.log.debug('sshd listening on port: %d', port)
> > -        return port
> > -
> > -    def ssh_connect(self, username, keyfile):
> > -        self.ssh_logger = logging.getLogger('ssh')
> > -        port = self.get_portfwd()
> >          self.ssh_session = ssh.Session('127.0.0.1', port=port,
> >                                         user=username, key=keyfile)
> >          for i in range(10):
> > diff --git a/tests/vm/basevm.py b/tests/vm/basevm.py
> > index 00f1d5ca8d..75ce07df36 100644
> > --- a/tests/vm/basevm.py
> > +++ b/tests/vm/basevm.py
> > @@ -21,6 +21,7 @@
> >  sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..', 
> > 'python'))
> >  from qemu.accel import kvm_available
> >  from qemu.machine import QEMUMachine
> > +from qemu.utils import get_info_usernet_hostfwd_port
> >  import subprocess
> >  import hashlib
> >  import argparse
> > @@ -306,11 +307,7 @@ def boot(self, img, extra_args=[]):
> >          self.console_init()
> >          usernet_info = guest.qmp("human-monitor-command",
> >                                   command_line="info usernet")
> > -        self.ssh_port = None
> > -        for l in usernet_info["return"].splitlines():
> > -            fields = l.split()
> > -            if "TCP[HOST_FORWARD]" in fields and "22" in fields:
> > -                self.ssh_port = l.split()[3]
> > +        self.ssh_port = get_info_usernet_hostfwd_port(usernet_info)
> >          if not self.ssh_port:
> >              raise Exception("Cannot find ssh port from 'info 
> > usernet':\n%s" % \
> >                              usernet_info)
> > --
> > 2.25.4
> >
> 
> Other than maybe a small adjustment to the
> get_info_usernet_hostfwd_port function:
> 
> Reviewed-by: Willian Rampazzo <willianr@redhat.com>
> 

Thanks for the review!
- Cleber.

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