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# Copyright Red Hat 2021, Jake Hunsaker <jhunsake@redhat.com> # This file is part of the sos project: https://github.com/sosreport/sos # # This copyrighted material is made available to anyone wishing to use, # modify, copy, or redistribute it subject to the terms and conditions of # version 2 of the GNU General Public License. # # See the LICENSE file in the source distribution for further information. import inspect import logging import pexpect import re from pipes import quote from sos.collector.exceptions import (ConnectionException, CommandTimeoutException) from sos.utilities import bold class RemoteTransport(): """The base class used for defining supported remote transports to connect to remote nodes in conjunction with `sos collect`. This abstraction is used to manage the backend connections to nodes so that SoSNode() objects can be leveraged generically to connect to nodes, inspect those nodes, and run commands on them. """ name = 'undefined' default_user = None def __init__(self, address, commons): self.address = address self.opts = commons['cmdlineopts'] self.tmpdir = commons['tmpdir'] self.need_sudo = commons['need_sudo'] self._hostname = None self.soslog = logging.getLogger('sos') self.ui_log = logging.getLogger('sos_ui') def _sanitize_log_msg(self, msg): """Attempts to obfuscate sensitive information in log messages such as passwords""" reg = r'(?P<var>(pass|key|secret|PASS|KEY|SECRET).*?=)(?P<value>.*?\s)' return re.sub(reg, r'\g<var>****** ', msg) def log_info(self, msg): """Used to print and log info messages""" caller = inspect.stack()[1][3] lmsg = '[%s:%s] %s' % (self.hostname, caller, msg) self.soslog.info(lmsg) def log_error(self, msg): """Used to print and log error messages""" caller = inspect.stack()[1][3] lmsg = '[%s:%s] %s' % (self.hostname, caller, msg) self.soslog.error(lmsg) def log_debug(self, msg): """Used to print and log debug messages""" msg = self._sanitize_log_msg(msg) caller = inspect.stack()[1][3] msg = '[%s:%s] %s' % (self.hostname, caller, msg) self.soslog.debug(msg) @property def hostname(self): if self._hostname and 'localhost' not in self._hostname: return self._hostname return self.address @property def connected(self): """Is the transport __currently__ connected to the node, or otherwise capable of seamlessly running a command or similar on the node? """ return False @property def remote_exec(self): """This is the command string needed to leverage the remote transport when executing commands. For example, for an SSH transport this would be the `ssh <options>` string prepended to any command so that the command is executed by the ssh binary. This is also referenced by the `remote_exec` parameter for policies when loading a policy for a remote node """ return None @classmethod def display_help(cls, section): if cls is RemoteTransport: return cls.display_self_help(section) section.set_title("%s Transport Detailed Help" % cls.name.title().replace('_', ' ')) if cls.__doc__ and cls.__doc__ is not RemoteTransport.__doc__: section.add_text(cls.__doc__) else: section.add_text( 'Detailed information not available for this transport' ) return None @classmethod def display_self_help(cls, section): section.set_title('SoS Remote Transport Help') section.add_text( "\nTransports define how SoS connects to nodes and executes " "commands on them for the purposes of an %s run. Generally, " "this means transports define how commands are wrapped locally " "so that they are executed on the remote node(s) instead." % bold('sos collect') ) section.add_text( "Transports are generally selected by the cluster profile loaded " "for a given execution, however users may explicitly set one " "using '%s'. Note that not all transports will function for all " "cluster/node types." % bold('--transport=$transport_name') ) section.add_text( 'By default, OpenSSH Control Persist is attempted. Additional ' 'information for each supported transport is available in the ' 'following help sections:\n' ) from sos.collector.sosnode import TRANSPORTS for transport in TRANSPORTS: _sec = bold("collect.transports.%s" % transport) _desc = "The '%s' transport" % transport.lower() section.add_text( f"{' ':>8}{_sec:<45}{_desc:<30}", newline=False ) def connect(self, password): """Perform the connection steps in order to ensure that we are able to connect to the node for all future operations. Note that this should not provide an interactive shell at this time. """ if self._connect(password): if not self._hostname: self._get_hostname() return True return False def _connect(self, password): """Actually perform the connection requirements. Should be overridden by specific transports that subclass RemoteTransport """ raise NotImplementedError("Transport %s does not define connect" % self.name) def reconnect(self, password): """Attempts to reconnect to the node using the standard connect() but does not do so indefinitely. This imposes a strict number of retry attempts before failing out """ attempts = 1 last_err = 'unknown' while attempts < 5: self.log_debug("Attempting reconnect (#%s) to node" % attempts) try: if self.connect(password): return True except Exception as err: self.log_debug("Attempt #%s exception: %s" % (attempts, err)) last_err = err attempts += 1 self.log_error("Unable to reconnect to node after 5 attempts, " "aborting.") raise ConnectionException("last exception from transport: %s" % last_err) def disconnect(self): """Perform whatever steps are necessary, if any, to terminate any connection to the node """ try: if self._disconnect(): self.log_debug("Successfully disconnected from node") else: self.log_error("Unable to successfully disconnect, see log for" " more details") except Exception as err: self.log_error("Failed to disconnect: %s" % err) def _disconnect(self): raise NotImplementedError("Transport %s does not define disconnect" % self.name) @property def _need_shell(self): """ Transports may override this to control when/if commands executed over the transport needs to utilize a shell on the remote host. """ return False def run_command(self, cmd, timeout=180, need_root=False, env=None, use_shell='auto'): """Run a command on the node, returning its output and exit code. This should return the exit code of the command being executed, not the exit code of whatever mechanism the transport uses to execute that command :param cmd: The command to run :type cmd: ``str`` :param timeout: The maximum time in seconds to allow the cmd to run :type timeout: ``int``` :param need_root: Does ``cmd`` require root privileges? :type need_root: ``bool`` :param env: Specify env vars to be passed to the ``cmd`` :type env: ``dict`` :param use_shell: Does ``cmd`` require execution within a shell? :type use_shell: ``bool`` or ``auto`` for transport-determined :returns: Output of ``cmd`` and the exit code :rtype: ``dict`` with keys ``output`` and ``status`` """ self.log_debug('Running command %s' % cmd) if (use_shell is True or (self._need_shell if use_shell == 'auto' else False)): cmd = "/bin/bash -c %s" % quote(cmd) self.log_debug(f"Shell requested, command is now {cmd}") # currently we only use/support the use of pexpect for handling the # execution of these commands, as opposed to directly invoking # subprocess.Popen() in conjunction with tools like sshpass. # If that changes in the future, we'll add decision making logic here # to route to the appropriate handler, but for now we just go straight # to using pexpect return self._run_command_with_pexpect(cmd, timeout, need_root, env) def _format_cmd_for_exec(self, cmd): """Format the command in the way needed for the remote transport to successfully execute it as one would when manually executing it :param cmd: The command being executed, as formatted by SoSNode :type cmd: ``str`` :returns: The command further formatted as needed by this transport :rtype: ``str`` """ cmd = "%s %s" % (self.remote_exec, quote(cmd)) cmd = cmd.lstrip() return cmd def _run_command_with_pexpect(self, cmd, timeout, need_root, env): """Execute the command using pexpect, which allows us to more easily handle prompts and timeouts compared to directly leveraging the subprocess.Popen() method. :param cmd: The command to execute. This will be automatically formatted to use the transport. :type cmd: ``str`` :param timeout: The maximum time in seconds to run ``cmd`` :type timeout: ``int`` :param need_root: Does ``cmd`` need to run as root or with sudo? :type need_root: ``bool`` :param env: Any env vars that ``cmd`` should be run with :type env: ``dict`` """ cmd = self._format_cmd_for_exec(cmd) # if for any reason env is empty, set it to None as otherwise # pexpect interprets this to mean "run this command with no env vars of # any kind" if not env: env = None try: result = pexpect.spawn(cmd, encoding='utf-8', env=env) except pexpect.exceptions.ExceptionPexpect as err: self.log_debug(err.value) return {'status': 127, 'output': ''} _expects = [pexpect.EOF, pexpect.TIMEOUT] if need_root and self.opts.ssh_user != 'root': _expects.extend([ '\\[sudo\\] password for .*:', 'Password:' ]) index = result.expect(_expects, timeout=timeout) if index in [2, 3]: self._send_pexpect_password(index, result) index = result.expect(_expects, timeout=timeout) if index == 0: out = result.before result.close() return {'status': result.exitstatus, 'output': out} elif index == 1: raise CommandTimeoutException(cmd) # if we somehow manage to flow to this point, use this bogus exit code # as a signal to debugging efforts that whatever went sideways did so # as part of the above block self.log_debug(f"Unexpected index {index} from pexpect: {result}") return {'status': 999, 'output': ''} def _send_pexpect_password(self, index, result): """Handle password prompts for sudo and su usage for non-root SSH users :param index: The index pexpect.spawn returned to match against either a sudo or su prompt :type index: ``int`` :param result: The spawn running the command :type result: ``pexpect.spawn`` """ if index == 2: if not self.opts.sudo_pw and not self.opt.nopasswd_sudo: msg = ("Unable to run command: sudo password " "required but not provided") self.log_error(msg) raise Exception(msg) result.sendline(self.opts.sudo_pw) elif index == 3: if not self.opts.root_password: msg = ("Unable to run command as root: no root password given") self.log_error(msg) raise Exception(msg) result.sendline(self.opts.root_password) def _get_hostname(self): """Determine the hostname of the node and set that for future reference and logging :returns: The hostname of the system, per the `hostname` command :rtype: ``str`` """ _out = self.run_command('hostname') if _out['status'] == 0: self._hostname = _out['output'].strip() if not self._hostname: self._hostname = self.address self.log_info("Hostname set to %s" % self._hostname) return self._hostname def retrieve_file(self, fname, dest): """Copy a remote file, fname, to dest on the local node :param fname: The name of the file to retrieve :type fname: ``str`` :param dest: Where to save the file to locally :type dest: ``str`` :returns: True if file was successfully copied from remote, or False :rtype: ``bool`` """ attempts = 0 try: while attempts < 5: attempts += 1 ret = self._retrieve_file(fname, dest) if ret: return True self.log_info("File retrieval attempt %s failed" % attempts) self.log_info("File retrieval failed after 5 attempts") return False except Exception as err: self.log_error("Exception encountered during retrieval attempt %s " "for %s: %s" % (attempts, fname, err)) raise err def _retrieve_file(self, fname, dest): raise NotImplementedError("Transport %s does not support file copying" % self.name) def read_file(self, fname): """Read the given file fname and return its contents :param fname: The name of the file to read :type fname: ``str`` :returns: The content of the file :rtype: ``str`` """ self.log_debug("Reading file %s" % fname) return self._read_file(fname) def _read_file(self, fname): res = self.run_command("cat %s" % fname, timeout=10) if res['status'] == 0: return res['output'] else: if 'No such file' in res['output']: self.log_debug("File %s does not exist on node" % fname) else: self.log_error("Error reading %s: %s" % (fname, res['output'].split(':')[1:])) return '' # vim: set et ts=4 sw=4 :