Merge "Add processutils from oslo."

2 files changed, 136 insertions, 1 deletions

diff --git a/nova/openstack/common/processutils.py b/nova/openstack/common/processutils.py
new file mode 100644
index 000000000..297f911c4
--- /dev/null
+++ b/nova/openstack/common/processutils.py
@@ -0,0 +1,135 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2011 OpenStack LLC.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+"""
+System-level utilities and helper functions.
+"""
+
+import logging
+import random
+import shlex
+
+from eventlet.green import subprocess
+from eventlet import greenthread
+
+from nova.openstack.common.gettextutils import _
+
+
+LOG = logging.getLogger(__name__)
+
+
+class UnknownArgumentError(Exception):
+    def __init__(self, message=None):
+        super(UnknownArgumentError, self).__init__(message)
+
+
+class ProcessExecutionError(Exception):
+    def __init__(self, stdout=None, stderr=None, exit_code=None, cmd=None,
+                 description=None):
+        if description is None:
+            description = "Unexpected error while running command."
+        if exit_code is None:
+            exit_code = '-'
+        message = ("%s\nCommand: %s\nExit code: %s\nStdout: %r\nStderr: %r"
+                   % (description, cmd, exit_code, stdout, stderr))
+        super(ProcessExecutionError, self).__init__(message)
+
+
+def execute(*cmd, **kwargs):
+    """
+    Helper method to shell out and execute a command through subprocess with
+    optional retry.
+
+    :param cmd:             Passed to subprocess.Popen.
+    :type cmd:              string
+    :param process_input:   Send to opened process.
+    :type proces_input:     string
+    :param check_exit_code: Defaults to 0. Will raise
+                            :class:`ProcessExecutionError`
+                            if the command exits without returning this value
+                            as a returncode
+    :type check_exit_code:  int
+    :param delay_on_retry:  True | False. Defaults to True. If set to True,
+                            wait a short amount of time before retrying.
+    :type delay_on_retry:   boolean
+    :param attempts:        How many times to retry cmd.
+    :type attempts:         int
+    :param run_as_root:     True | False. Defaults to False. If set to True,
+                            the command is prefixed by the command specified
+                            in the root_helper kwarg.
+    :type run_as_root:      boolean
+    :param root_helper:     command to prefix all cmd's with
+    :type root_helper:      string
+    :returns:               (stdout, stderr) from process execution
+    :raises:                :class:`UnknownArgumentError` on
+                            receiving unknown arguments
+    :raises:                :class:`ProcessExecutionError`
+    """
+
+    process_input = kwargs.pop('process_input', None)
+    check_exit_code = kwargs.pop('check_exit_code', 0)
+    delay_on_retry = kwargs.pop('delay_on_retry', True)
+    attempts = kwargs.pop('attempts', 1)
+    run_as_root = kwargs.pop('run_as_root', False)
+    root_helper = kwargs.pop('root_helper', '')
+    if len(kwargs):
+        raise UnknownArgumentError(_('Got unknown keyword args '
+                                     'to utils.execute: %r') % kwargs)
+    if run_as_root:
+        cmd = shlex.split(root_helper) + 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
+            obj = subprocess.Popen(cmd,
+                                   stdin=_PIPE,
+                                   stdout=_PIPE,
+                                   stderr=_PIPE,
+                                   close_fds=True)
+            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
+            if _returncode:
+                LOG.debug(_('Result was %s') % _returncode)
+                if (isinstance(check_exit_code, int) and
+                    not isinstance(check_exit_code, bool) and
+                        _returncode != check_exit_code):
+                    (stdout, stderr) = result
+                    raise ProcessExecutionError(exit_code=_returncode,
+                                                stdout=stdout,
+                                                stderr=stderr,
+                                                cmd=' '.join(cmd))
+            return result
+        except 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)
diff --git a/openstack-common.conf b/openstack-common.conf
index 463abd1c2..36abed038 100644
--- a/openstack-common.conf
+++ b/openstack-common.conf
@@ -1,7 +1,7 @@
 [DEFAULT]
 
 # The list of modules to copy from openstack-common
-modules=cliutils,context,db,db.api,db.sqlalchemy,excutils,eventlet_backdoor,fileutils,gettextutils,importutils,jsonutils,local,lockutils,log,network_utils,notifier,plugin,policy,rootwrap,setup,timeutils,rpc,uuidutils,install_venv_common,flakes,version
+modules=cliutils,context,db,db.api,db.sqlalchemy,excutils,eventlet_backdoor,fileutils,gettextutils,importutils,jsonutils,local,lockutils,log,network_utils,notifier,plugin,policy,rootwrap,setup,timeutils,rpc,uuidutils,install_venv_common,flakes,version,processutils
 
 # The base module to hold the copy of openstack.common
 base=nova