1d1e4ccb3e
Currently we pass a reference to a global "rollback" list to create() to keep rollback functions. Other nodes don't need to know about global rollback state, and by passing by reference we're giving them the chance to mess it up for everyone else. Add a "add_rollback()" function in NodeBase for create() calls to register rollback calls within themselves. As they hit rollback points they can add a new entry. lambda v arguments is much of a muchness -- but this is similar to the standard atexit() call so with go with that pattern. A new "rollback()" call is added that the driver will invoke on each node as it works its way backwards in case of failure. On error, nodes will have rollback() called in reverse order (which then calls registered rollbacks in reverse order). A unit test is added to test rollback behaviour Change-Id: I65214e72c7ef607dd08f750a6d32a0b10fe97ac3
137 lines
4.7 KiB
Python
137 lines
4.7 KiB
Python
# Copyright 2016 Andreas Florath (andreas@florath.net)
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import logging
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import os
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import subprocess
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from diskimage_builder.block_device.exception import \
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BlockDeviceSetupException
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from diskimage_builder.block_device.plugin import NodeBase
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from diskimage_builder.block_device.plugin import PluginBase
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from diskimage_builder.block_device.utils import parse_abs_size_spec
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logger = logging.getLogger(__name__)
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def image_create(filename, size):
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logger.info("Create image file [%s]", filename)
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with open(filename, "w") as fd:
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fd.seek(size - 1)
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fd.write("\0")
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def image_delete(filename):
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logger.info("Remove image file [%s]", filename)
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os.remove(filename)
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def loopdev_attach(filename):
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logger.info("loopdev attach")
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logger.debug("Calling [sudo losetup --show -f %s]", filename)
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subp = subprocess.Popen(["sudo", "losetup", "--show", "-f",
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filename], stdout=subprocess.PIPE)
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rval = subp.wait()
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if rval == 0:
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# [:-1]: Cut of the newline
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block_device = subp.stdout.read()[:-1].decode("utf-8")
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logger.info("New block device [%s]", block_device)
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return block_device
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else:
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logger.error("losetup failed")
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raise BlockDeviceSetupException("losetup failed")
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def loopdev_detach(loopdev):
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logger.info("loopdev detach")
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# loopback dev may be tied up a bit by udev events triggered
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# by partition events
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for try_cnt in range(10, 1, -1):
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logger.debug("Calling [sudo losetup -d %s]", loopdev)
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subp = subprocess.Popen(["sudo", "losetup", "-d",
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loopdev])
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rval = subp.wait()
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if rval == 0:
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logger.info("Successfully detached [%s]", loopdev)
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return 0
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else:
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logger.error("loopdev detach failed")
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# Do not raise an error - maybe other cleanup methods
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# can at least do some more work.
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logger.debug("Gave up trying to detach [%s]", loopdev)
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return rval
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class LocalLoopNode(NodeBase):
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"""Level0: Local loop image device handling.
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This class handles local loop devices that can be used
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for VM image installation.
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"""
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def __init__(self, config, default_config, state):
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logger.debug("Creating LocalLoop object; config [%s] "
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"default_config [%s]", config, default_config)
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super(LocalLoopNode, self).__init__(config['name'], state)
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if 'size' in config:
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self.size = parse_abs_size_spec(config['size'])
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logger.debug("Image size [%s]", self.size)
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else:
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self.size = parse_abs_size_spec(default_config['image-size'])
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logger.debug("Using default image size [%s]", self.size)
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if 'directory' in config:
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self.image_dir = config['directory']
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else:
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self.image_dir = default_config['image-dir']
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self.filename = os.path.join(self.image_dir, self.name + ".raw")
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def get_edges(self):
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"""Because this is created without base, there are no edges."""
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return ([], [])
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def create(self):
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logger.debug("[%s] Creating loop on [%s] with size [%d]",
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self.name, self.filename, self.size)
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self.add_rollback(image_delete, self.filename)
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image_create(self.filename, self.size)
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block_device = loopdev_attach(self.filename)
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self.add_rollback(loopdev_detach, block_device)
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if 'blockdev' not in self.state:
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self.state['blockdev'] = {}
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self.state['blockdev'][self.name] = {"device": block_device,
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"image": self.filename}
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logger.debug("Created loop name [%s] device [%s] image [%s]",
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self.name, block_device, self.filename)
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return
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def umount(self):
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loopdev_detach(self.state['blockdev'][self.name]['device'])
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def delete(self):
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image_delete(self.state['blockdev'][self.name]['image'])
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class LocalLoop(PluginBase):
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def __init__(self, config, defaults, state):
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super(LocalLoop, self).__init__()
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self.node = LocalLoopNode(config, defaults, state)
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def get_nodes(self):
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return [self.node]
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