root / lib / ssh.py @ 5349519d
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# Copyright (C) 2006, 2007, 2010, 2011 Google Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301, USA.
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"""Module encapsulating ssh functionality.
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"""
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import os |
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import logging |
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from ganeti import utils |
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from ganeti import errors |
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from ganeti import constants |
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from ganeti import netutils |
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from ganeti import pathutils |
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from ganeti import vcluster |
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from ganeti import compat |
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def GetUserFiles(user, mkdir=False, dircheck=True, kind=constants.SSHK_DSA, |
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_homedir_fn=None):
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"""Return the paths of a user's SSH files.
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@type user: string
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@param user: Username
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@type mkdir: bool
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@param mkdir: Whether to create ".ssh" directory if it doesn't exist
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@type dircheck: bool
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@param dircheck: Whether to check if ".ssh" directory exists
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@type kind: string
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@param kind: One of L{constants.SSHK_ALL}
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@rtype: tuple; (string, string, string)
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@return: Tuple containing three file system paths; the private SSH key file,
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the public SSH key file and the user's C{authorized_keys} file
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@raise errors.OpExecError: When home directory of the user can not be
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determined
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@raise errors.OpExecError: Regardless of the C{mkdir} parameters, this
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exception is raised if C{~$user/.ssh} is not a directory and C{dircheck}
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is set to C{True}
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"""
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if _homedir_fn is None: |
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_homedir_fn = utils.GetHomeDir |
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user_dir = _homedir_fn(user) |
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if not user_dir: |
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raise errors.OpExecError("Cannot resolve home of user '%s'" % user) |
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if kind == constants.SSHK_DSA:
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suffix = "dsa"
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elif kind == constants.SSHK_RSA:
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suffix = "rsa"
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else:
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raise errors.ProgrammerError("Unknown SSH key kind '%s'" % kind) |
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ssh_dir = utils.PathJoin(user_dir, ".ssh")
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if mkdir:
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utils.EnsureDirs([(ssh_dir, constants.SECURE_DIR_MODE)]) |
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elif dircheck and not os.path.isdir(ssh_dir): |
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raise errors.OpExecError("Path %s is not a directory" % ssh_dir) |
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return [utils.PathJoin(ssh_dir, base)
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for base in ["id_%s" % suffix, "id_%s.pub" % suffix, |
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"authorized_keys"]]
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def GetAllUserFiles(user, mkdir=False, dircheck=True, _homedir_fn=None): |
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"""Wrapper over L{GetUserFiles} to retrieve files for all SSH key types.
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See L{GetUserFiles} for details.
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@rtype: tuple; (string, dict with string as key, tuple of (string, string) as
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value)
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"""
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helper = compat.partial(GetUserFiles, user, mkdir=mkdir, dircheck=dircheck, |
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_homedir_fn=_homedir_fn) |
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result = [(kind, helper(kind=kind)) for kind in constants.SSHK_ALL] |
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authorized_keys = [i for (_, (_, _, i)) in result] |
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assert len(frozenset(authorized_keys)) == 1, \ |
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"Different paths for authorized_keys were returned"
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return (authorized_keys[0], |
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dict((kind, (privkey, pubkey))
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for (kind, (privkey, pubkey, _)) in result)) |
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class SshRunner: |
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"""Wrapper for SSH commands.
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"""
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def __init__(self, cluster_name, ipv6=False): |
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"""Initializes this class.
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@type cluster_name: str
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@param cluster_name: name of the cluster
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@type ipv6: bool
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@param ipv6: If true, force ssh to use IPv6 addresses only
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"""
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self.cluster_name = cluster_name
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self.ipv6 = ipv6
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def _BuildSshOptions(self, batch, ask_key, use_cluster_key, |
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strict_host_check, private_key=None, quiet=True, |
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port=None):
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"""Builds a list with needed SSH options.
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@param batch: same as ssh's batch option
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@param ask_key: allows ssh to ask for key confirmation; this
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parameter conflicts with the batch one
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@param use_cluster_key: if True, use the cluster name as the
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HostKeyAlias name
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@param strict_host_check: this makes the host key checking strict
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@param private_key: use this private key instead of the default
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@param quiet: whether to enable -q to ssh
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@param port: the SSH port to use, or None to use the default
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@rtype: list
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@return: the list of options ready to use in L{utils.process.RunCmd}
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"""
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options = [ |
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"-oEscapeChar=none",
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"-oHashKnownHosts=no",
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"-oGlobalKnownHostsFile=%s" % pathutils.SSH_KNOWN_HOSTS_FILE,
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"-oUserKnownHostsFile=/dev/null",
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"-oCheckHostIp=no",
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] |
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if use_cluster_key:
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options.append("-oHostKeyAlias=%s" % self.cluster_name) |
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if quiet:
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options.append("-q")
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if private_key:
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options.append("-i%s" % private_key)
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if port:
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options.append("-oPort=%d" % port)
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# TODO: Too many boolean options, maybe convert them to more descriptive
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# constants.
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# Note: ask_key conflicts with batch mode
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if batch:
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if ask_key:
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raise errors.ProgrammerError("SSH call requested conflicting options") |
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options.append("-oBatchMode=yes")
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if strict_host_check:
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options.append("-oStrictHostKeyChecking=yes")
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else:
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options.append("-oStrictHostKeyChecking=no")
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else:
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# non-batch mode
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if ask_key:
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options.append("-oStrictHostKeyChecking=ask")
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elif strict_host_check:
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options.append("-oStrictHostKeyChecking=yes")
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else:
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options.append("-oStrictHostKeyChecking=no")
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if self.ipv6: |
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options.append("-6")
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else:
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options.append("-4")
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return options
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def BuildCmd(self, hostname, user, command, batch=True, ask_key=False, |
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tty=False, use_cluster_key=True, strict_host_check=True, |
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private_key=None, quiet=True, port=None): |
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"""Build an ssh command to execute a command on a remote node.
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@param hostname: the target host, string
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@param user: user to auth as
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@param command: the command
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@param batch: if true, ssh will run in batch mode with no prompting
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@param ask_key: if true, ssh will run with
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StrictHostKeyChecking=ask, so that we can connect to an
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unknown host (not valid in batch mode)
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@param use_cluster_key: whether to expect and use the
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cluster-global SSH key
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@param strict_host_check: whether to check the host's SSH key at all
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@param private_key: use this private key instead of the default
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@param quiet: whether to enable -q to ssh
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@param port: the SSH port on which the node's daemon is running
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@return: the ssh call to run 'command' on the remote host.
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"""
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argv = [constants.SSH] |
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argv.extend(self._BuildSshOptions(batch, ask_key, use_cluster_key,
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strict_host_check, private_key, |
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quiet=quiet, port=port)) |
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if tty:
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argv.extend(["-t", "-t"]) |
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argv.append("%s@%s" % (user, hostname))
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# Insert variables for virtual nodes
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argv.extend("export %s=%s;" %
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(utils.ShellQuote(name), utils.ShellQuote(value)) |
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for (name, value) in |
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vcluster.EnvironmentForHost(hostname).items()) |
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argv.append(command) |
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return argv
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def Run(self, *args, **kwargs): |
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"""Runs a command on a remote node.
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This method has the same return value as `utils.RunCmd()`, which it
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uses to launch ssh.
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Args: see SshRunner.BuildCmd.
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@rtype: L{utils.process.RunResult}
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@return: the result as from L{utils.process.RunCmd()}
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"""
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return utils.RunCmd(self.BuildCmd(*args, **kwargs)) |
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def CopyFileToNode(self, node, port, filename): |
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"""Copy a file to another node with scp.
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@param node: node in the cluster
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@param filename: absolute pathname of a local file
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@rtype: boolean
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@return: the success of the operation
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"""
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if not os.path.isabs(filename): |
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logging.error("File %s must be an absolute path", filename)
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return False |
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if not os.path.isfile(filename): |
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logging.error("File %s does not exist", filename)
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return False |
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command = [constants.SCP, "-p"]
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command.extend(self._BuildSshOptions(True, False, True, True, port=port)) |
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command.append(filename) |
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if netutils.IP6Address.IsValid(node):
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node = netutils.FormatAddress((node, None))
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command.append("%s:%s" % (node, vcluster.ExchangeNodeRoot(node, filename)))
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result = utils.RunCmd(command) |
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if result.failed:
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logging.error("Copy to node %s failed (%s) error '%s',"
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" command was '%s'",
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node, result.fail_reason, result.output, result.cmd) |
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return not result.failed |
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def VerifyNodeHostname(self, node, ssh_port): |
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"""Verify hostname consistency via SSH.
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This functions connects via ssh to a node and compares the hostname
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reported by the node to the name with have (the one that we
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connected to).
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This is used to detect problems in ssh known_hosts files
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(conflicting known hosts) and inconsistencies between dns/hosts
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entries and local machine names
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@param node: nodename of a host to check; can be short or
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full qualified hostname
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@param ssh_port: the port of a SSH daemon running on the node
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@return: (success, detail), where:
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- success: True/False
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- detail: string with details
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"""
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cmd = ("if test -z \"$GANETI_HOSTNAME\"; then"
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" hostname --fqdn;"
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"else"
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" echo \"$GANETI_HOSTNAME\";"
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"fi")
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retval = self.Run(node, constants.SSH_LOGIN_USER, cmd,
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quiet=False, port=ssh_port)
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if retval.failed:
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msg = "ssh problem"
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output = retval.output |
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if output:
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msg += ": %s" % output
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else:
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msg += ": %s (no output)" % retval.fail_reason
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logging.error("Command %s failed: %s", retval.cmd, msg)
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return False, msg |
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remotehostname = retval.stdout.strip() |
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if not remotehostname or remotehostname != node: |
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if node.startswith(remotehostname + "."): |
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msg = "hostname not FQDN"
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else:
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msg = "hostname mismatch"
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return False, ("%s: expected %s but got %s" % |
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(msg, node, remotehostname)) |
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return True, "host matches" |
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def WriteKnownHostsFile(cfg, file_name): |
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"""Writes the cluster-wide equally known_hosts file.
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"""
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data = ""
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if cfg.GetRsaHostKey():
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data += "%s ssh-rsa %s\n" % (cfg.GetClusterName(), cfg.GetRsaHostKey())
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if cfg.GetDsaHostKey():
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data += "%s ssh-dss %s\n" % (cfg.GetClusterName(), cfg.GetDsaHostKey())
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utils.WriteFile(file_name, mode=0600, data=data)
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