Convert to using oslo's execute() method.

There are some small warts (mostly around other execute() like
methods which reuse the exception). I will fix these warts in later
reviews.

Change-Id: Ice9cdbdc5f3e5a9f8365f5d99acf1863a9fe3e7a

28 files changed, 97 insertions, 268 deletions

diff --git a/nova/cmd/baremetal_deploy_helper.py b/nova/cmd/baremetal_deploy_helper.py
index 365451b6b..dd8c652ff 100644
--- a/nova/cmd/baremetal_deploy_helper.py
+++ b/nova/cmd/baremetal_deploy_helper.py
@@ -32,8 +32,8 @@ from wsgiref import simple_server
 
 from nova import config
 from nova import context as nova_context
-from nova import exception
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova import utils
 from nova.virt.baremetal import baremetal_states
 from nova.virt.baremetal import db
@@ -201,7 +201,7 @@ def deploy(address, port, iqn, lun, image_path, pxe_config_path,
     login_iscsi(address, port, iqn)
     try:
         root_uuid = work_on_disk(dev, root_mb, swap_mb, image_path)
-    except exception.ProcessExecutionError, err:
+    except processutils.ProcessExecutionError, err:
         # Log output if there was a error
         LOG.error("Cmd     : %s" % err.cmd)
         LOG.error("StdOut  : %s" % err.stdout)
diff --git a/nova/console/xvp.py b/nova/console/xvp.py
index 1e9fbcb5d..be3a41c1d 100644
--- a/nova/console/xvp.py
+++ b/nova/console/xvp.py
@@ -25,9 +25,9 @@ from oslo.config import cfg
 
 from nova import context
 from nova import db
-from nova import exception
 from nova.openstack.common import excutils
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova import paths
 from nova import utils
 
@@ -143,7 +143,7 @@ class XVPConsoleProxy(object):
                           '-p', CONF.console_xvp_pid,
                           '-c', CONF.console_xvp_conf,
                           '-l', CONF.console_xvp_log)
-        except exception.ProcessExecutionError, err:
+        except processutils.ProcessExecutionError, err:
             LOG.error(_('Error starting xvp: %s') % err)
 
     def _xvp_restart(self):
@@ -200,5 +200,5 @@ class XVPConsoleProxy(object):
         password = password[:maxlen]
         out, err = utils.execute('xvp', flag, process_input=password)
         if err:
-            raise exception.ProcessExecutionError(_("Failed to run xvp."))
+            raise processutils.ProcessExecutionError(_("Failed to run xvp."))
         return out.strip()
diff --git a/nova/crypto.py b/nova/crypto.py
index 736e99961..aaf102d8a 100644
--- a/nova/crypto.py
+++ b/nova/crypto.py
@@ -41,6 +41,7 @@ from nova import exception
 from nova.openstack.common import excutils
 from nova.openstack.common import fileutils
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova.openstack.common import timeutils
 from nova import paths
 from nova import utils
@@ -138,7 +139,7 @@ def generate_fingerprint(public_key):
             with open(pubfile, 'w') as f:
                 f.write(public_key)
             return _generate_fingerprint(pubfile)
-        except exception.ProcessExecutionError:
+        except processutils.ProcessExecutionError:
             raise exception.InvalidKeypair()
 
 
@@ -184,7 +185,7 @@ def decrypt_text(project_id, text):
                                   '-inkey', '%s' % private_key,
                                   process_input=text)
         return dec
-    except exception.ProcessExecutionError as exc:
+    except processutils.ProcessExecutionError as exc:
         raise exception.DecryptionFailure(reason=exc.stderr)
 
 
@@ -267,7 +268,7 @@ def ssh_encrypt_text(ssh_public_key, text):
                                       '-keyform', 'PEM',
                                       process_input=text)
             return enc
-        except exception.ProcessExecutionError as exc:
+        except processutils.ProcessExecutionError as exc:
             raise exception.EncryptionFailure(reason=exc.stderr)
 
 
diff --git a/nova/exception.py b/nova/exception.py
index c81362dcf..a9afe37a7 100644
--- a/nova/exception.py
+++ b/nova/exception.py
@@ -53,25 +53,6 @@ class ConvertedException(webob.exc.WSGIHTTPException):
         super(ConvertedException, self).__init__()
 
 
-class ProcessExecutionError(IOError):
-    def __init__(self, stdout=None, stderr=None, exit_code=None, cmd=None,
-                 description=None):
-        self.exit_code = exit_code
-        self.stderr = stderr
-        self.stdout = stdout
-        self.cmd = cmd
-        self.description = description
-
-        if description is None:
-            description = _('Unexpected error while running command.')
-        if exit_code is None:
-            exit_code = '-'
-        message = _('%(description)s\nCommand: %(cmd)s\n'
-                    'Exit code: %(exit_code)s\nStdout: %(stdout)r\n'
-                    'Stderr: %(stderr)r') % locals()
-        IOError.__init__(self, message)
-
-
 def _cleanse_dict(original):
     """Strip all admin_password, new_pass, rescue_pass keys from a dict."""
     return dict((k, v) for k, v in original.iteritems() if not "_pass" in k)
diff --git a/nova/image/s3.py b/nova/image/s3.py
index 563864b91..f08cbcdcb 100644
--- a/nova/image/s3.py
+++ b/nova/image/s3.py
@@ -35,6 +35,7 @@ import nova.cert.rpcapi
 from nova import exception
 from nova.image import glance
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova import utils
 
 
@@ -409,7 +410,7 @@ class S3ImageService(object):
                           '-K', '%s' % (key,),
                           '-iv', '%s' % (iv,),
                           '-out', '%s' % (decrypted_filename,))
-        except exception.ProcessExecutionError, exc:
+        except processutils.ProcessExecutionError, exc:
             raise exception.NovaException(_('Failed to decrypt image file '
                                     '%(image_file)s: %(err)s') %
                                     {'image_file': encrypted_filename,
diff --git a/nova/network/floating_ips.py b/nova/network/floating_ips.py
index bc8c05d26..8ba153358 100644
--- a/nova/network/floating_ips.py
+++ b/nova/network/floating_ips.py
@@ -28,6 +28,7 @@ from nova.openstack.common import importutils
 from nova.openstack.common import lockutils
 from nova.openstack.common import log as logging
 from nova.openstack.common.notifier import api as notifier
+from nova.openstack.common import processutils
 from nova.openstack.common.rpc import common as rpc_common
 from nova.openstack.common import uuidutils
 from nova import quota
@@ -93,7 +94,7 @@ class FloatingIP(object):
                                                   fixed_ip['address'],
                                                   interface,
                                                   fixed_ip['network'])
-                except exception.ProcessExecutionError:
+                except processutils.ProcessExecutionError:
                     LOG.debug(_('Interface %(interface)s not found'), locals())
                     raise exception.NoFloatingIpInterface(interface=interface)
 
@@ -367,7 +368,7 @@ class FloatingIP(object):
                 # gogo driver time
                 self.l3driver.add_floating_ip(floating_address, fixed_address,
                         interface, fixed['network'])
-            except exception.ProcessExecutionError as e:
+            except processutils.ProcessExecutionError as e:
                 self.db.floating_ip_disassociate(context, floating_address)
                 if "Cannot find device" in str(e):
                     LOG.error(_('Interface %(interface)s not found'), locals())
diff --git a/nova/network/linux_net.py b/nova/network/linux_net.py
index fad51dbe1..7a1f562e5 100644
--- a/nova/network/linux_net.py
+++ b/nova/network/linux_net.py
@@ -35,6 +35,7 @@ from nova.openstack.common import importutils
 from nova.openstack.common import jsonutils
 from nova.openstack.common import lockutils
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova.openstack.common import timeutils
 from nova import paths
 from nova import utils
@@ -771,7 +772,7 @@ def clean_conntrack(fixed_ip):
     try:
         _execute('conntrack', '-D', '-r', fixed_ip, run_as_root=True,
                  check_exit_code=[0, 1])
-    except exception.ProcessExecutionError:
+    except processutils.ProcessExecutionError:
         LOG.exception(_('Error deleting conntrack entries for %s'), fixed_ip)
 
 
@@ -1260,7 +1261,7 @@ def create_tap_dev(dev, mac_address=None):
             # First, try with 'ip'
             utils.execute('ip', 'tuntap', 'add', dev, 'mode', 'tap',
                           run_as_root=True, check_exit_code=[0, 2, 254])
-        except exception.ProcessExecutionError:
+        except processutils.ProcessExecutionError:
             # Second option: tunctl
             utils.execute('tunctl', '-b', '-t', dev, run_as_root=True)
         if mac_address:
@@ -1277,7 +1278,7 @@ def delete_net_dev(dev):
             utils.execute('ip', 'link', 'delete', dev, run_as_root=True,
                           check_exit_code=[0, 2, 254])
             LOG.debug(_("Net device removed: '%s'"), dev)
-        except exception.ProcessExecutionError:
+        except processutils.ProcessExecutionError:
             with excutils.save_and_reraise_exception():
                 LOG.error(_("Failed removing net device: '%s'"), dev)
 
diff --git a/nova/openstack/common/processutils.py b/nova/openstack/common/processutils.py
index fbd2c6ff2..45a5bf963 100644
--- a/nova/openstack/common/processutils.py
+++ b/nova/openstack/common/processutils.py
@@ -42,6 +42,12 @@ class UnknownArgumentError(Exception):
 class ProcessExecutionError(Exception):
     def __init__(self, stdout=None, stderr=None, exit_code=None, cmd=None,
                  description=None):
+        self.exit_code = exit_code
+        self.stderr = stderr
+        self.stdout = stdout
+        self.cmd = cmd
+        self.description = description
+
         if description is None:
             description = "Unexpected error while running command."
         if exit_code is None:
diff --git a/nova/storage/linuxscsi.py b/nova/storage/linuxscsi.py
index fb093b08a..66cb9c0ea 100644
--- a/nova/storage/linuxscsi.py
+++ b/nova/storage/linuxscsi.py
@@ -16,9 +16,9 @@
 
 """Generic linux scsi subsystem utilities."""
 
-from nova import exception
 from nova.openstack.common import log as logging
 from nova.openstack.common import loopingcall
+from nova.openstack.common import processutils
 from nova import utils
 
 LOG = logging.getLogger(__name__)
@@ -97,7 +97,7 @@ def find_multipath_device(device):
     try:
         (out, err) = utils.execute('multipath', '-l', device,
                                run_as_root=True)
-    except exception.ProcessExecutionError as exc:
+    except processutils.ProcessExecutionError as exc:
         LOG.warn(_("Multipath call failed exit (%(code)s)")
                  % {'code': exc.exit_code})
         return None
diff --git a/nova/tests/baremetal/test_virtual_power_driver.py b/nova/tests/baremetal/test_virtual_power_driver.py
index b98ef5182..4cac0a3ba 100644
--- a/nova/tests/baremetal/test_virtual_power_driver.py
+++ b/nova/tests/baremetal/test_virtual_power_driver.py
@@ -22,6 +22,7 @@ import mox
 from oslo.config import cfg
 
 from nova import exception
+from nova.openstack.common import processutils
 from nova.tests.baremetal.db import base as bm_db_base
 from nova.tests.baremetal.db import utils as bm_db_utils
 from nova.tests.image import fake as fake_image
@@ -371,7 +372,7 @@ class VPDClassMethodsTestCase(BareMetalVPDTestCase):
         self.pm._set_connection().AndReturn(True)
         nutils.ssh_execute(None, '/usr/bin/VBoxManage test return',
                 check_exit_code=True).\
-                AndRaise(exception.ProcessExecutionError)
+                AndRaise(processutils.ProcessExecutionError)
         self.mox.ReplayAll()
 
         result = self.pm._run_command("test return")
@@ -389,10 +390,10 @@ class VPDClassMethodsTestCase(BareMetalVPDTestCase):
         self.pm._check_for_node().AndReturn(['"testNode"'])
         nutils.ssh_execute('test', '/usr/bin/VBoxManage startvm ',
                 check_exit_code=True).\
-                AndRaise(exception.ProcessExecutionError)
+                AndRaise(processutils.ProcessExecutionError)
         nutils.ssh_execute('test', '/usr/bin/VBoxManage list runningvms',
                 check_exit_code=True).\
-                AndRaise(exception.ProcessExecutionError)
+                AndRaise(processutils.ProcessExecutionError)
 
         self.mox.ReplayAll()
         self.pm._connection = 'test'
diff --git a/nova/tests/fake_utils.py b/nova/tests/fake_utils.py
index 08a84e73f..6a295b43b 100644
--- a/nova/tests/fake_utils.py
+++ b/nova/tests/fake_utils.py
@@ -20,8 +20,8 @@ import re
 
 from eventlet import greenthread
 
-from nova import exception
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova import utils
 
 LOG = logging.getLogger(__name__)
@@ -92,7 +92,7 @@ def fake_execute(*cmd_parts, **kwargs):
                                   attempts=attempts,
                                   run_as_root=run_as_root,
                                   check_exit_code=check_exit_code)
-        except exception.ProcessExecutionError as e:
+        except processutils.ProcessExecutionError as e:
             LOG.debug(_('Faked command raised an exception %s'), e)
             raise
 
diff --git a/nova/tests/network/test_manager.py b/nova/tests/network/test_manager.py
index def993f62..b8d7115a9 100644
--- a/nova/tests/network/test_manager.py
+++ b/nova/tests/network/test_manager.py
@@ -32,6 +32,7 @@ from nova.network import model as net_model
 from nova.openstack.common.db import exception as db_exc
 from nova.openstack.common import importutils
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova.openstack.common import rpc
 from nova.openstack.common.rpc import common as rpc_common
 from nova import quota
@@ -763,7 +764,7 @@ class VlanNetworkTestCase(test.TestCase):
             self.local = True
 
         def fake8(*args, **kwargs):
-            raise exception.ProcessExecutionError('',
+            raise processutils.ProcessExecutionError('',
                     'Cannot find device "em0"\n')
 
         def fake9(*args, **kwargs):
diff --git a/nova/tests/test_crypto.py b/nova/tests/test_crypto.py
index e328babfe..2264273d7 100644
--- a/nova/tests/test_crypto.py
+++ b/nova/tests/test_crypto.py
@@ -23,6 +23,7 @@ import mox
 from nova import crypto
 from nova import db
 from nova import exception
+from nova.openstack.common import processutils
 from nova import test
 from nova import utils
 
@@ -200,7 +201,7 @@ e6fCXWECgYEAqgpGvva5kJ1ISgNwnJbwiNw0sOT9BMOsdNZBElf0kJIIy6FMPvap
                                           '-inkey', sshkey,
                                           process_input=text)
                 return dec
-            except exception.ProcessExecutionError as exc:
+            except processutils.ProcessExecutionError as exc:
                 raise exception.DecryptionFailure(reason=exc.stderr)
 
     def test_ssh_encrypt_decrypt_text(self):
diff --git a/nova/tests/test_powervm.py b/nova/tests/test_powervm.py
index 96954269e..73299f23a 100644
--- a/nova/tests/test_powervm.py
+++ b/nova/tests/test_powervm.py
@@ -22,13 +22,13 @@ import contextlib
 
 from nova import context
 from nova import db
-from nova import exception as nova_exception
 from nova import test
 
 from nova.compute import instance_types
 from nova.compute import power_state
 from nova.compute import task_states
 from nova.network import model as network_model
+from nova.openstack.common import processutils
 from nova.tests import fake_network_cache_model
 from nova.tests.image import fake
 from nova.virt import images
@@ -227,7 +227,7 @@ class PowerVMDriverTestCase(test.TestCase):
             self.powervm_connection._powervm,
             'get_host_stats',
             lambda *x, **y: raise_(
-                (nova_exception.ProcessExecutionError('instance_name'))))
+                (processutils.ProcessExecutionError('instance_name'))))
         fake_net_info = network_model.NetworkInfo([
                                      fake_network_cache_model.new_vif()])
         self.assertRaises(exception.PowerVMLPARCreationFailed,
diff --git a/nova/tests/test_utils.py b/nova/tests/test_utils.py
index af6a9b9aa..6b7af48fc 100644
--- a/nova/tests/test_utils.py
+++ b/nova/tests/test_utils.py
@@ -30,6 +30,7 @@ from oslo.config import cfg
 
 import nova
 from nova import exception
+from nova.openstack.common import processutils
 from nova.openstack.common import timeutils
 from nova import test
 from nova import utils
@@ -72,89 +73,6 @@ class ByteConversionTest(test.TestCase):
             self.assertRaises(TypeError, utils.to_bytes, v)
 
 
-class ExecuteTestCase(test.TestCase):
-
-    def test_retry_on_failure(self):
-        fd, tmpfilename = tempfile.mkstemp()
-        _, tmpfilename2 = tempfile.mkstemp()
-        try:
-            fp = os.fdopen(fd, 'w+')
-            fp.write('''#!/bin/sh
-# If stdin fails to get passed during one of the runs, make a note.
-if ! grep -q foo
-then
-    echo 'failure' > "$1"
-fi
-# If stdin has failed to get passed during this or a previous run, exit early.
-if grep failure "$1"
-then
-    exit 1
-fi
-runs="$(cat $1)"
-if [ -z "$runs" ]
-then
-    runs=0
-fi
-runs=$(($runs + 1))
-echo $runs > "$1"
-exit 1
-''')
-            fp.close()
-            os.chmod(tmpfilename, 0755)
-            self.assertRaises(exception.ProcessExecutionError,
-                              utils.execute,
-                              tmpfilename, tmpfilename2, attempts=10,
-                              process_input='foo',
-                              delay_on_retry=False)
-            fp = open(tmpfilename2, 'r')
-            runs = fp.read()
-            fp.close()
-            self.assertNotEquals(runs.strip(), 'failure', 'stdin did not '
-                                                          'always get passed '
-                                                          'correctly')
-            runs = int(runs.strip())
-            self.assertEquals(runs, 10,
-                              'Ran %d times instead of 10.' % (runs,))
-        finally:
-            os.unlink(tmpfilename)
-            os.unlink(tmpfilename2)
-
-    def test_unknown_kwargs_raises_error(self):
-        self.assertRaises(exception.NovaException,
-                          utils.execute,
-                          '/usr/bin/env', 'true',
-                          this_is_not_a_valid_kwarg=True)
-
-    def test_check_exit_code_boolean(self):
-        utils.execute('/usr/bin/env', 'false', check_exit_code=False)
-        self.assertRaises(exception.ProcessExecutionError,
-                          utils.execute,
-                          '/usr/bin/env', 'false', check_exit_code=True)
-
-    def test_no_retry_on_success(self):
-        fd, tmpfilename = tempfile.mkstemp()
-        _, tmpfilename2 = tempfile.mkstemp()
-        try:
-            fp = os.fdopen(fd, 'w+')
-            fp.write('''#!/bin/sh
-# If we've already run, bail out.
-grep -q foo "$1" && exit 1
-# Mark that we've run before.
-echo foo > "$1"
-# Check that stdin gets passed correctly.
-grep foo
-''')
-            fp.close()
-            os.chmod(tmpfilename, 0755)
-            utils.execute(tmpfilename,
-                          tmpfilename2,
-                          process_input='foo',
-                          attempts=2)
-        finally:
-            os.unlink(tmpfilename)
-            os.unlink(tmpfilename2)
-
-
 class GetFromPathTestCase(test.TestCase):
     def test_tolerates_nones(self):
         f = utils.get_from_path
@@ -429,7 +347,7 @@ class GenericUtilsTestCase(test.TestCase):
     def test_read_file_as_root(self):
         def fake_execute(*args, **kwargs):
             if args[1] == 'bad':
-                raise exception.ProcessExecutionError
+                raise processutils.ProcessExecutionError
             return 'fakecontents', None
 
         self.stubs.Set(utils, 'execute', fake_execute)
diff --git a/nova/utils.py b/nova/utils.py
index bb002b9e7..64606f4f8 100644
--- a/nova/utils.py
+++ b/nova/utils.py
@@ -30,7 +30,6 @@ import pyclbr
 import random
 import re
 import shutil
-import signal
 import socket
 import struct
 import sys
@@ -38,8 +37,6 @@ import tempfile
 import time
 from xml.sax import saxutils
 
-from eventlet.green import subprocess
-from eventlet import greenthread
 import netaddr
 
 from oslo.config import cfg
@@ -48,6 +45,7 @@ from nova import exception
 from nova.openstack.common import excutils
 from nova.openstack.common import importutils
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova.openstack.common.rpc import common as rpc_common
 from nova.openstack.common import timeutils
 
@@ -149,107 +147,11 @@ def vpn_ping(address, port, timeout=0.05, session_id=None):
         return server_sess
 
 
-def _subprocess_setup():
-    # Python installs a SIGPIPE handler by default. This is usually not what
-    # non-Python subprocesses expect.
-    signal.signal(signal.SIGPIPE, signal.SIG_DFL)
-
-
 def execute(*cmd, **kwargs):
-    """Helper method to execute command with optional retry.
-
-    If you add a run_as_root=True command, don't forget to add the
-    corresponding filter to etc/nova/rootwrap.d !
-
-    :param cmd:                Passed to subprocess.Popen.
-    :param process_input:      Send to opened process.
-    :param check_exit_code:    Single bool, int, or list of allowed exit
-                               codes.  Defaults to [0].  Raise
-                               exception.ProcessExecutionError unless
-                               program exits with one of these code.
-    :param delay_on_retry:     True | False. Defaults to True. If set to
-                               True, wait a short amount of time
-                               before retrying.
-    :param attempts:           How many times to retry cmd.
-    :param run_as_root:        True | False. Defaults to False. If set to True,
-                               the command is run with rootwrap.
-
-    :raises exception.NovaException: on receiving unknown arguments
-    :raises exception.ProcessExecutionError:
-
-    :returns: a tuple, (stdout, stderr) from the spawned process, or None if
-             the command fails.
-    """
-    process_input = kwargs.pop('process_input', None)
-    check_exit_code = kwargs.pop('check_exit_code', [0])
-    ignore_exit_code = False
-    if isinstance(check_exit_code, bool):
-        ignore_exit_code = not check_exit_code
-        check_exit_code = [0]
-    elif isinstance(check_exit_code, int):
-        check_exit_code = [check_exit_code]
-    delay_on_retry = kwargs.pop('delay_on_retry', True)
-    attempts = kwargs.pop('attempts', 1)
-    run_as_root = kwargs.pop('run_as_root', False)
-    shell = kwargs.pop('shell', False)
-
-    if len(kwargs):
-        raise exception.NovaException(_('Got unknown keyword args '
-                                        'to utils.execute: %r') % kwargs)
-
-    if run_as_root and os.geteuid() != 0:
-        cmd = ['sudo', 'nova-rootwrap', CONF.rootwrap_config] + list(cmd)
-
-    cmd = map(str, cmd)
-
-    while attempts > 0:
-        attempts -= 1
-        try:
-            LOG.debug(_('Running cmd (subprocess): %s'), ' '.join(cmd))
-            _PIPE = subprocess.PIPE  # pylint: disable=E1101
-
-            if os.name == 'nt':
-                preexec_fn = None
-                close_fds = False
-            else:
-                preexec_fn = _subprocess_setup
-                close_fds = True
-
-            obj = subprocess.Popen(cmd,
-                                   stdin=_PIPE,
-                                   stdout=_PIPE,
-                                   stderr=_PIPE,
-                                   close_fds=close_fds,
-                                   preexec_fn=preexec_fn,
-                                   shell=shell)
-            result = None
-            if process_input is not None:
-                result = obj.communicate(process_input)
-            else:
-                result = obj.communicate()
-            obj.stdin.close()  # pylint: disable=E1101
-            _returncode = obj.returncode  # pylint: disable=E1101
-            LOG.debug(_('Result was %s') % _returncode)
-            if not ignore_exit_code and _returncode not in check_exit_code:
-                (stdout, stderr) = result
-                raise exception.ProcessExecutionError(
-                        exit_code=_returncode,
-                        stdout=stdout,
-                        stderr=stderr,
-                        cmd=' '.join(cmd))
-            return result
-        except exception.ProcessExecutionError:
-            if not attempts:
-                raise
-            else:
-                LOG.debug(_('%r failed. Retrying.'), cmd)
-                if delay_on_retry:
-                    greenthread.sleep(random.randint(20, 200) / 100.0)
-        finally:
-            # NOTE(termie): this appears to be necessary to let the subprocess
-            #               call clean something up in between calls, without
-            #               it two execute calls in a row hangs the second one
-            greenthread.sleep(0)
+    """Convenience wrapper around oslo's execute() method."""
+    if 'run_as_root' in kwargs and not 'root_helper' in kwargs:
+        kwargs['root_helper'] = 'sudo nova-rootwrap %s' % CONF.rootwrap_config
+    return processutils.execute(*cmd, **kwargs)
 
 
 def trycmd(*args, **kwargs):
@@ -269,7 +171,7 @@ def trycmd(*args, **kwargs):
     try:
         out, err = execute(*args, **kwargs)
         failed = False
-    except exception.ProcessExecutionError, exn:
+    except processutils.ProcessExecutionError, exn:
         out, err = '', str(exn)
         failed = True
 
@@ -309,10 +211,13 @@ def ssh_execute(ssh, cmd, process_input=None,
     if exit_status != -1:
         LOG.debug(_('Result was %s') % exit_status)
         if check_exit_code and exit_status != 0:
-            raise exception.ProcessExecutionError(exit_code=exit_status,
-                                                  stdout=stdout,
-                                                  stderr=stderr,
-                                                  cmd=cmd)
+            # TODO(mikal): I know this is a bit odd, but its needed for
+            # consistency. I will move this method into processutils in a
+            # later change.
+            raise processutils.ProcessExecutionError(exit_code=exit_status,
+                                                     stdout=stdout,
+                                                     stderr=stderr,
+                                                     cmd=cmd)
 
     return (stdout, stderr)
 
@@ -1066,7 +971,7 @@ def read_file_as_root(file_path):
     try:
         out, _err = execute('cat', file_path, run_as_root=True)
         return out
-    except exception.ProcessExecutionError:
+    except processutils.ProcessExecutionError:
         raise exception.FileNotFound(file_path=file_path)
 
 
diff --git a/nova/virt/baremetal/tilera_pdu.py b/nova/virt/baremetal/tilera_pdu.py
index 86e6086ae..0e491168f 100755
--- a/nova/virt/baremetal/tilera_pdu.py
+++ b/nova/virt/baremetal/tilera_pdu.py
@@ -26,6 +26,7 @@ from oslo.config import cfg
 
 from nova import exception
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova import utils
 from nova.virt.baremetal import baremetal_states
 from nova.virt.baremetal import base
@@ -104,7 +105,7 @@ class Pdu(base.PowerManager):
                 utils.execute('ping', '-c1', self.address,
                        check_exit_code=True)
                 return CONF.baremetal.tile_pdu_on
-            except exception.ProcessExecutionError:
+            except processutils.ProcessExecutionError:
                 return CONF.baremetal.tile_pdu_off
         else:
             try:
@@ -112,7 +113,7 @@ class Pdu(base.PowerManager):
                           CONF.baremetal.tile_pdu_ip, mode)
                 time.sleep(CONF.baremetal.tile_power_wait)
                 return mode
-            except exception.ProcessExecutionError:
+            except processutils.ProcessExecutionError:
                 LOG.exception(_("PDU failed"))
 
     def _is_power(self, state):
diff --git a/nova/virt/baremetal/virtual_power_driver.py b/nova/virt/baremetal/virtual_power_driver.py
index 2e659b8c3..22dd815d0 100644
--- a/nova/virt/baremetal/virtual_power_driver.py
+++ b/nova/virt/baremetal/virtual_power_driver.py
@@ -23,6 +23,7 @@ from nova import context as nova_context
 from nova import exception
 from nova.openstack.common import importutils
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova import utils
 from nova.virt.baremetal import baremetal_states
 from nova.virt.baremetal import base
@@ -233,7 +234,7 @@ class VirtualPowerManager(base.PowerManager):
                                            check_exit_code=check_exit_code)
             result = stdout.strip().splitlines()
             LOG.debug('Result for run_command: %s' % result)
-        except exception.ProcessExecutionError:
+        except processutils.ProcessExecutionError:
             result = []
             LOG.exception("Error running command: %s" % cmd)
         return result
diff --git a/nova/virt/baremetal/volume_driver.py b/nova/virt/baremetal/volume_driver.py
index cc23f9064..6cf6b775f 100644
--- a/nova/virt/baremetal/volume_driver.py
+++ b/nova/virt/baremetal/volume_driver.py
@@ -24,6 +24,7 @@ from nova import context as nova_context
 from nova import exception
 from nova.openstack.common import importutils
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova import utils
 from nova.virt.baremetal import db as bmdb
 from nova.virt.libvirt import utils as libvirt_utils
@@ -91,7 +92,7 @@ def _delete_iscsi_export_tgtadm(tid):
                       '--tid', tid,
                       '--lun', '1',
                       run_as_root=True)
-    except exception.ProcessExecutionError:
+    except processutils.ProcessExecutionError:
         pass
     try:
         utils.execute('tgtadm', '--lld', 'iscsi',
@@ -99,7 +100,7 @@ def _delete_iscsi_export_tgtadm(tid):
                       '--op', 'delete',
                       '--tid', tid,
                       run_as_root=True)
-    except exception.ProcessExecutionError:
+    except processutils.ProcessExecutionError:
         pass
     # Check if the tid is deleted, that is, check the tid no longer exists.
     # If the tid dose not exist, tgtadm returns with exit_code 22.
@@ -113,7 +114,7 @@ def _delete_iscsi_export_tgtadm(tid):
                       '--op', 'show',
                       '--tid', tid,
                       run_as_root=True)
-    except exception.ProcessExecutionError as e:
+    except processutils.ProcessExecutionError as e:
         if e.exit_code == 22:
             # OK, the tid is deleted
             return
diff --git a/nova/virt/disk/api.py b/nova/virt/disk/api.py
index 497e2baaa..2c5def493 100755
--- a/nova/virt/disk/api.py
+++ b/nova/virt/disk/api.py
@@ -37,6 +37,7 @@ from oslo.config import cfg
 from nova import exception
 from nova.openstack.common import jsonutils
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova import paths
 from nova import utils
 from nova.virt.disk.mount import api as mount
@@ -155,7 +156,7 @@ def can_resize_fs(image, size, use_cow=False):
         # For raw, we can directly inspect the file system
         try:
             utils.execute('e2label', image)
-        except exception.ProcessExecutionError as e:
+        except processutils.ProcessExecutionError as e:
             LOG.debug(_('Unable to determine label for image %(image)s with '
                         'error %(errror)s. Cannot resize.'),
                       {'image': image,
diff --git a/nova/virt/hyperv/vmops.py b/nova/virt/hyperv/vmops.py
index 615567c0d..2bda94a35 100644
--- a/nova/virt/hyperv/vmops.py
+++ b/nova/virt/hyperv/vmops.py
@@ -28,6 +28,7 @@ from nova import exception
 from nova.openstack.common import excutils
 from nova.openstack.common import importutils
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova import utils
 from nova.virt import configdrive
 from nova.virt.hyperv import constants
@@ -229,7 +230,7 @@ class VMOps(object):
         with configdrive.ConfigDriveBuilder(instance_md=inst_md) as cdb:
             try:
                 cdb.make_drive(configdrive_path_iso)
-            except exception.ProcessExecutionError as e:
+            except processutils.ProcessExecutionError as e:
                 with excutils.save_and_reraise_exception():
                     LOG.error(_('Creating config drive failed with error: %s'),
                               e, instance=instance)
diff --git a/nova/virt/libvirt/driver.py b/nova/virt/libvirt/driver.py
index e8a0a46eb..a0d2d0a7b 100755
--- a/nova/virt/libvirt/driver.py
+++ b/nova/virt/libvirt/driver.py
@@ -77,6 +77,7 @@ from nova.openstack.common import jsonutils
 from nova.openstack.common import log as logging
 from nova.openstack.common import loopingcall
 from nova.openstack.common.notifier import api as notifier
+from nova.openstack.common import processutils
 from nova import utils
 from nova import version
 from nova.virt import configdrive
@@ -1871,7 +1872,7 @@ class LibvirtDriver(driver.ComputeDriver):
 
                 try:
                     cdb.make_drive(configdrive_path)
-                except exception.ProcessExecutionError as e:
+                except processutils.ProcessExecutionError as e:
                     with excutils.save_and_reraise_exception():
                         LOG.error(_('Creating config drive failed '
                                   'with error: %s'),
@@ -3236,7 +3237,7 @@ class LibvirtDriver(driver.ComputeDriver):
             try:
                 self.plug_vifs(instance, network_info)
                 break
-            except exception.ProcessExecutionError:
+            except processutils.ProcessExecutionError:
                 if cnt == max_retry - 1:
                     raise
                 else:
diff --git a/nova/virt/libvirt/utils.py b/nova/virt/libvirt/utils.py
index 96f84c194..07ab44769 100755
--- a/nova/virt/libvirt/utils.py
+++ b/nova/virt/libvirt/utils.py
@@ -26,8 +26,8 @@ import os
 from lxml import etree
 from oslo.config import cfg
 
-from nova import exception
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova import utils
 from nova.virt import images
 
@@ -64,7 +64,7 @@ def get_fc_hbas():
     try:
         out, err = execute('systool', '-c', 'fc_host', '-v',
                            run_as_root=True)
-    except exception.ProcessExecutionError as exc:
+    except processutils.ProcessExecutionError as exc:
         # This handles the case where rootwrap is used
         # and systool is not installed
         # 96 = nova.cmd.rootwrap.RC_NOEXECFOUND:
@@ -427,7 +427,7 @@ def copy_image(src, dest, host=None):
             # can fall back to scp, without having run out of space
             # on the destination for example.
             execute('rsync', '--sparse', '--compress', '--dry-run', src, dest)
-        except exception.ProcessExecutionError:
+        except processutils.ProcessExecutionError:
             execute('scp', src, dest)
         else:
             execute('rsync', '--sparse', '--compress', src, dest)
diff --git a/nova/virt/libvirt/vif.py b/nova/virt/libvirt/vif.py
index db7bb96d8..28c481cfe 100644
--- a/nova/virt/libvirt/vif.py
+++ b/nova/virt/libvirt/vif.py
@@ -27,6 +27,7 @@ from nova import exception
 from nova.network import linux_net
 from nova.network import model as network_model
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova import utils
 from nova.virt.libvirt import config as vconfig
 from nova.virt.libvirt import designer
@@ -417,7 +418,7 @@ class LibvirtGenericVIFDriver(LibvirtBaseVIFDriver):
             network, mapping = vif
             linux_net.delete_ovs_vif_port(self.get_bridge_name(network),
                                           self.get_vif_devname(mapping))
-        except exception.ProcessExecutionError:
+        except processutils.ProcessExecutionError:
             LOG.exception(_("Failed while unplugging vif"), instance=instance)
 
     def unplug_ovs_bridge(self, instance, vif):
@@ -446,7 +447,7 @@ class LibvirtGenericVIFDriver(LibvirtBaseVIFDriver):
 
             linux_net.delete_ovs_vif_port(self.get_bridge_name(network),
                                           v2_name)
-        except exception.ProcessExecutionError:
+        except processutils.ProcessExecutionError:
             LOG.exception(_("Failed while unplugging vif"), instance=instance)
 
     def unplug_ovs(self, instance, vif):
diff --git a/nova/virt/libvirt/volume.py b/nova/virt/libvirt/volume.py
index 1d226ae83..5f8d4bd72 100644
--- a/nova/virt/libvirt/volume.py
+++ b/nova/virt/libvirt/volume.py
@@ -30,6 +30,7 @@ from nova import exception
 from nova.openstack.common import lockutils
 from nova.openstack.common import log as logging
 from nova.openstack.common import loopingcall
+from nova.openstack.common import processutils
 from nova import paths
 from nova.storage import linuxscsi
 from nova import utils
@@ -314,7 +315,7 @@ class LibvirtISCSIVolumeDriver(LibvirtBaseVolumeDriver):
         #             volume is using the same target.
         try:
             self._run_iscsiadm(iscsi_properties, ())
-        except exception.ProcessExecutionError as exc:
+        except processutils.ProcessExecutionError as exc:
             # iscsiadm returns 21 for "No records found" after version 2.0-871
             if exc.exit_code in [21, 255]:
                 self._run_iscsiadm(iscsi_properties, ('--op', 'new'))
@@ -353,7 +354,7 @@ class LibvirtISCSIVolumeDriver(LibvirtBaseVolumeDriver):
                 self._run_iscsiadm(iscsi_properties,
                                    ("--login",),
                                    check_exit_code=[0, 255])
-            except exception.ProcessExecutionError as err:
+            except processutils.ProcessExecutionError as err:
                 #as this might be one of many paths,
                 #only set successfull logins to startup automatically
                 if err.exit_code in [15]:
@@ -484,7 +485,7 @@ class LibvirtNFSVolumeDriver(LibvirtBaseVolumeDriver):
 
         try:
             utils.execute(*nfs_cmd, run_as_root=True)
-        except exception.ProcessExecutionError as exc:
+        except processutils.ProcessExecutionError as exc:
             if ensure and 'already mounted' in exc.message:
                 LOG.warn(_("%s is already mounted"), nfs_share)
             else:
@@ -500,7 +501,7 @@ class LibvirtNFSVolumeDriver(LibvirtBaseVolumeDriver):
         """Check path."""
         try:
             return utils.execute('stat', path, run_as_root=True)
-        except exception.ProcessExecutionError:
+        except processutils.ProcessExecutionError:
             return False
 
 
@@ -605,7 +606,7 @@ class LibvirtGlusterfsVolumeDriver(LibvirtBaseVolumeDriver):
             utils.execute('mount', '-t', 'glusterfs', glusterfs_share,
                           mount_path,
                           run_as_root=True)
-        except exception.ProcessExecutionError as exc:
+        except processutils.ProcessExecutionError as exc:
             if ensure and 'already mounted' in exc.message:
                 LOG.warn(_("%s is already mounted"), glusterfs_share)
             else:
@@ -621,7 +622,7 @@ class LibvirtGlusterfsVolumeDriver(LibvirtBaseVolumeDriver):
         """Check path."""
         try:
             return utils.execute('stat', path, run_as_root=True)
-        except exception.ProcessExecutionError:
+        except processutils.ProcessExecutionError:
             return False
 
 
diff --git a/nova/virt/powervm/common.py b/nova/virt/powervm/common.py
index 34658547c..dd6517dcd 100644
--- a/nova/virt/powervm/common.py
+++ b/nova/virt/powervm/common.py
@@ -21,8 +21,8 @@ import uuid
 
 import paramiko
 
-from nova import exception as nova_exception
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova import utils
 from nova.virt.powervm import constants
 from nova.virt.powervm import exception
@@ -68,7 +68,7 @@ def ssh_command_as_root(ssh_connection, cmd, check_exit_code=True):
     :param connection: an active paramiko.SSHClient connection.
     :param command: string containing the command to run.
     :returns: Tuple -- a tuple of (stdout, stderr)
-    :raises: nova.exception.ProcessExecutionError
+    :raises: processutils.ProcessExecutionError
     """
     LOG.debug(_('Running cmd (SSH-as-root): %s') % cmd)
     chan = ssh_connection._transport.open_session()
@@ -89,10 +89,13 @@ def ssh_command_as_root(ssh_connection, cmd, check_exit_code=True):
     if exit_status != -1:
         LOG.debug(_('Result was %s') % exit_status)
         if check_exit_code and exit_status != 0:
-            raise nova_exception.ProcessExecutionError(exit_code=exit_status,
-                                                       stdout=stdout,
-                                                       stderr=stderr,
-                                                       cmd=''.join(cmd))
+            # TODO(mikal): I know this is weird, but it needs to be consistent
+            # with processutils.execute. I will move this method to oslo in
+            # a later commit.
+            raise processutils.ProcessExecutionError(exit_code=exit_status,
+                                                     stdout=stdout,
+                                                     stderr=stderr,
+                                                     cmd=''.join(cmd))
 
     return (stdout, stderr)
 
diff --git a/nova/virt/powervm/operator.py b/nova/virt/powervm/operator.py
index 946835224..b5ead9064 100644
--- a/nova/virt/powervm/operator.py
+++ b/nova/virt/powervm/operator.py
@@ -22,9 +22,9 @@ import time
 from oslo.config import cfg
 
 from nova.compute import power_state
-from nova import exception as nova_exception
 from nova.openstack.common import excutils
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova import utils
 from nova.virt.powervm import blockdev
 from nova.virt.powervm import command
@@ -199,7 +199,7 @@ class PowerVMOperator(object):
                 #             system (1 in 2^28)
                 self._operator.create_lpar(lpar_inst)
                 LOG.debug(_("Creating LPAR instance '%s'") % instance['name'])
-            except nova_exception.ProcessExecutionError:
+            except processutils.ProcessExecutionError:
                 LOG.exception(_("LPAR instance '%s' creation failed") %
                         instance['name'])
                 raise exception.PowerVMLPARCreationFailed(
diff --git a/nova/virt/xenapi/vm_utils.py b/nova/virt/xenapi/vm_utils.py
index e569216c8..9832dca84 100644
--- a/nova/virt/xenapi/vm_utils.py
+++ b/nova/virt/xenapi/vm_utils.py
@@ -44,6 +44,7 @@ from nova import exception
 from nova.image import glance
 from nova.openstack.common import excutils
 from nova.openstack.common import log as logging
+from nova.openstack.common import processutils
 from nova import utils
 from nova.virt import configdrive
 from nova.virt.disk import api as disk
@@ -1979,7 +1980,7 @@ def _is_vdi_pv(dev):
                 LOG.debug(_("Found Xen kernel %s") % m.group(0))
                 return True
         LOG.debug(_("No Xen kernel found.  Booting HVM."))
-    except exception.ProcessExecutionError:
+    except processutils.ProcessExecutionError:
         LOG.exception(_("Error while executing pygrub! Please, ensure the "
                         "binary is installed correctly, and available in your "
                         "PATH; on some Linux distros, pygrub may be installed "
@@ -2161,7 +2162,7 @@ def _mount_filesystem(dev_path, dir):
         _out, err = utils.execute('mount',
                                  '-t', 'ext2,ext3,ext4,reiserfs',
                                  dev_path, dir, run_as_root=True)
-    except exception.ProcessExecutionError as e:
+    except processutils.ProcessExecutionError as e:
         err = str(e)
     return err